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linux/drivers/scsi/scsi_lib.c
152587deb8 [PATCH] fix NMI lockup with CFQ scheduler 
The current problem seen is that the queue lock is actually in the
SCSI device structure, so when that structure is freed on device
release, we go boom if the queue tries to access the lock again.

The fix here is to move the lock from the scsi_device to the queue.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2005-04-16 20:10:09 -05:00

2024 lines
53 KiB
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/*
* scsi_lib.c Copyright (C) 1999 Eric Youngdale
*
* SCSI queueing library.
* Initial versions: Eric Youngdale (eric@andante.org).
* Based upon conversations with large numbers
* of people at Linux Expo.
*/
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/completion.h>
#include <linux/kernel.h>
#include <linux/mempool.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/delay.h>
#include <scsi/scsi.h>
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_driver.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_request.h>
#include "scsi_priv.h"
#include "scsi_logging.h"
#define SG_MEMPOOL_NR (sizeof(scsi_sg_pools)/sizeof(struct scsi_host_sg_pool))
#define SG_MEMPOOL_SIZE 32
struct scsi_host_sg_pool {
size_t size;
char *name;
kmem_cache_t *slab;
mempool_t *pool;
};
#if (SCSI_MAX_PHYS_SEGMENTS < 32)
#error SCSI_MAX_PHYS_SEGMENTS is too small
#endif
#define SP(x) { x, "sgpool-" #x }
struct scsi_host_sg_pool scsi_sg_pools[] = {
SP(8),
SP(16),
SP(32),
#if (SCSI_MAX_PHYS_SEGMENTS > 32)
SP(64),
#if (SCSI_MAX_PHYS_SEGMENTS > 64)
SP(128),
#if (SCSI_MAX_PHYS_SEGMENTS > 128)
SP(256),
#if (SCSI_MAX_PHYS_SEGMENTS > 256)
#error SCSI_MAX_PHYS_SEGMENTS is too large
#endif
#endif
#endif
#endif
};
#undef SP
/*
* Function: scsi_insert_special_req()
*
* Purpose: Insert pre-formed request into request queue.
*
* Arguments: sreq - request that is ready to be queued.
* at_head - boolean. True if we should insert at head
* of queue, false if we should insert at tail.
*
* Lock status: Assumed that lock is not held upon entry.
*
* Returns: Nothing
*
* Notes: This function is called from character device and from
* ioctl types of functions where the caller knows exactly
* what SCSI command needs to be issued. The idea is that
* we merely inject the command into the queue (at the head
* for now), and then call the queue request function to actually
* process it.
*/
int scsi_insert_special_req(struct scsi_request *sreq, int at_head)
{
/*
* Because users of this function are apt to reuse requests with no
* modification, we have to sanitise the request flags here
*/
sreq->sr_request->flags &= ~REQ_DONTPREP;
blk_insert_request(sreq->sr_device->request_queue, sreq->sr_request,
at_head, sreq, 0);
return 0;
}
/*
* Function: scsi_queue_insert()
*
* Purpose: Insert a command in the midlevel queue.
*
* Arguments: cmd - command that we are adding to queue.
* reason - why we are inserting command to queue.
*
* Lock status: Assumed that lock is not held upon entry.
*
* Returns: Nothing.
*
* Notes: We do this for one of two cases. Either the host is busy
* and it cannot accept any more commands for the time being,
* or the device returned QUEUE_FULL and can accept no more
* commands.
* Notes: This could be called either from an interrupt context or a
* normal process context.
*/
int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
{
struct Scsi_Host *host = cmd->device->host;
struct scsi_device *device = cmd->device;
SCSI_LOG_MLQUEUE(1,
printk("Inserting command %p into mlqueue\n", cmd));
/*
* We are inserting the command into the ml queue. First, we
* cancel the timer, so it doesn't time out.
*/
scsi_delete_timer(cmd);
/*
* Next, set the appropriate busy bit for the device/host.
*
* If the host/device isn't busy, assume that something actually
* completed, and that we should be able to queue a command now.
*
* Note that the prior mid-layer assumption that any host could
* always queue at least one command is now broken. The mid-layer
* will implement a user specifiable stall (see
* scsi_host.max_host_blocked and scsi_device.max_device_blocked)
* if a command is requeued with no other commands outstanding
* either for the device or for the host.
*/
if (reason == SCSI_MLQUEUE_HOST_BUSY)
host->host_blocked = host->max_host_blocked;
else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
device->device_blocked = device->max_device_blocked;
/*
* Register the fact that we own the thing for now.
*/
cmd->state = SCSI_STATE_MLQUEUE;
cmd->owner = SCSI_OWNER_MIDLEVEL;
/*
* Decrement the counters, since these commands are no longer
* active on the host/device.
*/
scsi_device_unbusy(device);
/*
* Insert this command at the head of the queue for it's device.
* It will go before all other commands that are already in the queue.
*
* NOTE: there is magic here about the way the queue is plugged if
* we have no outstanding commands.
*
* Although this *doesn't* plug the queue, it does call the request
* function. The SCSI request function detects the blocked condition
* and plugs the queue appropriately.
*/
blk_insert_request(device->request_queue, cmd->request, 1, cmd, 1);
return 0;
}
/*
* Function: scsi_do_req
*
* Purpose: Queue a SCSI request
*
* Arguments: sreq - command descriptor.
* cmnd - actual SCSI command to be performed.
* buffer - data buffer.
* bufflen - size of data buffer.
* done - completion function to be run.
* timeout - how long to let it run before timeout.
* retries - number of retries we allow.
*
* Lock status: No locks held upon entry.
*
* Returns: Nothing.
*
* Notes: This function is only used for queueing requests for things
* like ioctls and character device requests - this is because
* we essentially just inject a request into the queue for the
* device.
*
* In order to support the scsi_device_quiesce function, we
* now inject requests on the *head* of the device queue
* rather than the tail.
*/
void scsi_do_req(struct scsi_request *sreq, const void *cmnd,
void *buffer, unsigned bufflen,
void (*done)(struct scsi_cmnd *),
int timeout, int retries)
{
/*
* If the upper level driver is reusing these things, then
* we should release the low-level block now. Another one will
* be allocated later when this request is getting queued.
*/
__scsi_release_request(sreq);
/*
* Our own function scsi_done (which marks the host as not busy,
* disables the timeout counter, etc) will be called by us or by the
* scsi_hosts[host].queuecommand() function needs to also call
* the completion function for the high level driver.
*/
memcpy(sreq->sr_cmnd, cmnd, sizeof(sreq->sr_cmnd));
sreq->sr_bufflen = bufflen;
sreq->sr_buffer = buffer;
sreq->sr_allowed = retries;
sreq->sr_done = done;
sreq->sr_timeout_per_command = timeout;
if (sreq->sr_cmd_len == 0)
sreq->sr_cmd_len = COMMAND_SIZE(sreq->sr_cmnd[0]);
/*
* head injection *required* here otherwise quiesce won't work
*/
scsi_insert_special_req(sreq, 1);
}
EXPORT_SYMBOL(scsi_do_req);
static void scsi_wait_done(struct scsi_cmnd *cmd)
{
struct request *req = cmd->request;
struct request_queue *q = cmd->device->request_queue;
unsigned long flags;
req->rq_status = RQ_SCSI_DONE; /* Busy, but indicate request done */
spin_lock_irqsave(q->queue_lock, flags);
if (blk_rq_tagged(req))
blk_queue_end_tag(q, req);
spin_unlock_irqrestore(q->queue_lock, flags);
if (req->waiting)
complete(req->waiting);
}
/* This is the end routine we get to if a command was never attached
* to the request. Simply complete the request without changing
* rq_status; this will cause a DRIVER_ERROR. */
static void scsi_wait_req_end_io(struct request *req)
{
BUG_ON(!req->waiting);
complete(req->waiting);
}
void scsi_wait_req(struct scsi_request *sreq, const void *cmnd, void *buffer,
unsigned bufflen, int timeout, int retries)
{
DECLARE_COMPLETION(wait);
sreq->sr_request->waiting = &wait;
sreq->sr_request->rq_status = RQ_SCSI_BUSY;
sreq->sr_request->end_io = scsi_wait_req_end_io;
scsi_do_req(sreq, cmnd, buffer, bufflen, scsi_wait_done,
timeout, retries);
wait_for_completion(&wait);
sreq->sr_request->waiting = NULL;
if (sreq->sr_request->rq_status != RQ_SCSI_DONE)
sreq->sr_result |= (DRIVER_ERROR << 24);
__scsi_release_request(sreq);
}
EXPORT_SYMBOL(scsi_wait_req);
/*
* Function: scsi_init_cmd_errh()
*
* Purpose: Initialize cmd fields related to error handling.
*
* Arguments: cmd - command that is ready to be queued.
*
* Returns: Nothing
*
* Notes: This function has the job of initializing a number of
* fields related to error handling. Typically this will
* be called once for each command, as required.
*/
static int scsi_init_cmd_errh(struct scsi_cmnd *cmd)
{
cmd->owner = SCSI_OWNER_MIDLEVEL;
cmd->serial_number = 0;
cmd->serial_number_at_timeout = 0;
cmd->abort_reason = 0;
memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
if (cmd->cmd_len == 0)
cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
/*
* We need saved copies of a number of fields - this is because
* error handling may need to overwrite these with different values
* to run different commands, and once error handling is complete,
* we will need to restore these values prior to running the actual
* command.
*/
cmd->old_use_sg = cmd->use_sg;
cmd->old_cmd_len = cmd->cmd_len;
cmd->sc_old_data_direction = cmd->sc_data_direction;
cmd->old_underflow = cmd->underflow;
memcpy(cmd->data_cmnd, cmd->cmnd, sizeof(cmd->cmnd));
cmd->buffer = cmd->request_buffer;
cmd->bufflen = cmd->request_bufflen;
cmd->internal_timeout = NORMAL_TIMEOUT;
cmd->abort_reason = 0;
return 1;
}
/*
* Function: scsi_setup_cmd_retry()
*
* Purpose: Restore the command state for a retry
*
* Arguments: cmd - command to be restored
*
* Returns: Nothing
*
* Notes: Immediately prior to retrying a command, we need
* to restore certain fields that we saved above.
*/
void scsi_setup_cmd_retry(struct scsi_cmnd *cmd)
{
memcpy(cmd->cmnd, cmd->data_cmnd, sizeof(cmd->data_cmnd));
cmd->request_buffer = cmd->buffer;
cmd->request_bufflen = cmd->bufflen;
cmd->use_sg = cmd->old_use_sg;
cmd->cmd_len = cmd->old_cmd_len;
cmd->sc_data_direction = cmd->sc_old_data_direction;
cmd->underflow = cmd->old_underflow;
}
void scsi_device_unbusy(struct scsi_device *sdev)
{
struct Scsi_Host *shost = sdev->host;
unsigned long flags;
spin_lock_irqsave(shost->host_lock, flags);
shost->host_busy--;
if (unlikely(test_bit(SHOST_RECOVERY, &shost->shost_state) &&
shost->host_failed))
scsi_eh_wakeup(shost);
spin_unlock(shost->host_lock);
spin_lock(sdev->request_queue->queue_lock);
sdev->device_busy--;
spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
}
/*
* Called for single_lun devices on IO completion. Clear starget_sdev_user,
* and call blk_run_queue for all the scsi_devices on the target -
* including current_sdev first.
*
* Called with *no* scsi locks held.
*/
static void scsi_single_lun_run(struct scsi_device *current_sdev)
{
struct Scsi_Host *shost = current_sdev->host;
struct scsi_device *sdev, *tmp;
struct scsi_target *starget = scsi_target(current_sdev);
unsigned long flags;
spin_lock_irqsave(shost->host_lock, flags);
starget->starget_sdev_user = NULL;
spin_unlock_irqrestore(shost->host_lock, flags);
/*
* Call blk_run_queue for all LUNs on the target, starting with
* current_sdev. We race with others (to set starget_sdev_user),
* but in most cases, we will be first. Ideally, each LU on the
* target would get some limited time or requests on the target.
*/
blk_run_queue(current_sdev->request_queue);
spin_lock_irqsave(shost->host_lock, flags);
if (starget->starget_sdev_user)
goto out;
list_for_each_entry_safe(sdev, tmp, &starget->devices,
same_target_siblings) {
if (sdev == current_sdev)
continue;
if (scsi_device_get(sdev))
continue;
spin_unlock_irqrestore(shost->host_lock, flags);
blk_run_queue(sdev->request_queue);
spin_lock_irqsave(shost->host_lock, flags);
scsi_device_put(sdev);
}
out:
spin_unlock_irqrestore(shost->host_lock, flags);
}
/*
* Function: scsi_run_queue()
*
* Purpose: Select a proper request queue to serve next
*
* Arguments: q - last request's queue
*
* Returns: Nothing
*
* Notes: The previous command was completely finished, start
* a new one if possible.
*/
static void scsi_run_queue(struct request_queue *q)
{
struct scsi_device *sdev = q->queuedata;
struct Scsi_Host *shost = sdev->host;
unsigned long flags;
if (sdev->single_lun)
scsi_single_lun_run(sdev);
spin_lock_irqsave(shost->host_lock, flags);
while (!list_empty(&shost->starved_list) &&
!shost->host_blocked && !shost->host_self_blocked &&
!((shost->can_queue > 0) &&
(shost->host_busy >= shost->can_queue))) {
/*
* As long as shost is accepting commands and we have
* starved queues, call blk_run_queue. scsi_request_fn
* drops the queue_lock and can add us back to the
* starved_list.
*
* host_lock protects the starved_list and starved_entry.
* scsi_request_fn must get the host_lock before checking
* or modifying starved_list or starved_entry.
*/
sdev = list_entry(shost->starved_list.next,
struct scsi_device, starved_entry);
list_del_init(&sdev->starved_entry);
spin_unlock_irqrestore(shost->host_lock, flags);
blk_run_queue(sdev->request_queue);
spin_lock_irqsave(shost->host_lock, flags);
if (unlikely(!list_empty(&sdev->starved_entry)))
/*
* sdev lost a race, and was put back on the
* starved list. This is unlikely but without this
* in theory we could loop forever.
*/
break;
}
spin_unlock_irqrestore(shost->host_lock, flags);
blk_run_queue(q);
}
/*
* Function: scsi_requeue_command()
*
* Purpose: Handle post-processing of completed commands.
*
* Arguments: q - queue to operate on
* cmd - command that may need to be requeued.
*
* Returns: Nothing
*
* Notes: After command completion, there may be blocks left
* over which weren't finished by the previous command
* this can be for a number of reasons - the main one is
* I/O errors in the middle of the request, in which case
* we need to request the blocks that come after the bad
* sector.
*/
static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
{
cmd->request->flags &= ~REQ_DONTPREP;
blk_insert_request(q, cmd->request, 1, cmd, 1);
scsi_run_queue(q);
}
void scsi_next_command(struct scsi_cmnd *cmd)
{
struct request_queue *q = cmd->device->request_queue;
scsi_put_command(cmd);
scsi_run_queue(q);
}
void scsi_run_host_queues(struct Scsi_Host *shost)
{
struct scsi_device *sdev;
shost_for_each_device(sdev, shost)
scsi_run_queue(sdev->request_queue);
}
/*
* Function: scsi_end_request()
*
* Purpose: Post-processing of completed commands (usually invoked at end
* of upper level post-processing and scsi_io_completion).
*
* Arguments: cmd - command that is complete.
* uptodate - 1 if I/O indicates success, <= 0 for I/O error.
* bytes - number of bytes of completed I/O
* requeue - indicates whether we should requeue leftovers.
*
* Lock status: Assumed that lock is not held upon entry.
*
* Returns: cmd if requeue done or required, NULL otherwise
*
* Notes: This is called for block device requests in order to
* mark some number of sectors as complete.
*
* We are guaranteeing that the request queue will be goosed
* at some point during this call.
*/
static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
int bytes, int requeue)
{
request_queue_t *q = cmd->device->request_queue;
struct request *req = cmd->request;
unsigned long flags;
/*
* If there are blocks left over at the end, set up the command
* to queue the remainder of them.
*/
if (end_that_request_chunk(req, uptodate, bytes)) {
int leftover = (req->hard_nr_sectors << 9);
if (blk_pc_request(req))
leftover = req->data_len;
/* kill remainder if no retrys */
if (!uptodate && blk_noretry_request(req))
end_that_request_chunk(req, 0, leftover);
else {
if (requeue)
/*
* Bleah. Leftovers again. Stick the
* leftovers in the front of the
* queue, and goose the queue again.
*/
scsi_requeue_command(q, cmd);
return cmd;
}
}
add_disk_randomness(req->rq_disk);
spin_lock_irqsave(q->queue_lock, flags);
if (blk_rq_tagged(req))
blk_queue_end_tag(q, req);
end_that_request_last(req);
spin_unlock_irqrestore(q->queue_lock, flags);
/*
* This will goose the queue request function at the end, so we don't
* need to worry about launching another command.
*/
scsi_next_command(cmd);
return NULL;
}
static struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, int gfp_mask)
{
struct scsi_host_sg_pool *sgp;
struct scatterlist *sgl;
BUG_ON(!cmd->use_sg);
switch (cmd->use_sg) {
case 1 ... 8:
cmd->sglist_len = 0;
break;
case 9 ... 16:
cmd->sglist_len = 1;
break;
case 17 ... 32:
cmd->sglist_len = 2;
break;
#if (SCSI_MAX_PHYS_SEGMENTS > 32)
case 33 ... 64:
cmd->sglist_len = 3;
break;
#if (SCSI_MAX_PHYS_SEGMENTS > 64)
case 65 ... 128:
cmd->sglist_len = 4;
break;
#if (SCSI_MAX_PHYS_SEGMENTS > 128)
case 129 ... 256:
cmd->sglist_len = 5;
break;
#endif
#endif
#endif
default:
return NULL;
}
sgp = scsi_sg_pools + cmd->sglist_len;
sgl = mempool_alloc(sgp->pool, gfp_mask);
if (sgl)
memset(sgl, 0, sgp->size);
return sgl;
}
static void scsi_free_sgtable(struct scatterlist *sgl, int index)
{
struct scsi_host_sg_pool *sgp;
BUG_ON(index > SG_MEMPOOL_NR);
sgp = scsi_sg_pools + index;
mempool_free(sgl, sgp->pool);
}
/*
* Function: scsi_release_buffers()
*
* Purpose: Completion processing for block device I/O requests.
*
* Arguments: cmd - command that we are bailing.
*
* Lock status: Assumed that no lock is held upon entry.
*
* Returns: Nothing
*
* Notes: In the event that an upper level driver rejects a
* command, we must release resources allocated during
* the __init_io() function. Primarily this would involve
* the scatter-gather table, and potentially any bounce
* buffers.
*/
static void scsi_release_buffers(struct scsi_cmnd *cmd)
{
struct request *req = cmd->request;
/*
* Free up any indirection buffers we allocated for DMA purposes.
*/
if (cmd->use_sg)
scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
else if (cmd->request_buffer != req->buffer)
kfree(cmd->request_buffer);
/*
* Zero these out. They now point to freed memory, and it is
* dangerous to hang onto the pointers.
*/
cmd->buffer = NULL;
cmd->bufflen = 0;
cmd->request_buffer = NULL;
cmd->request_bufflen = 0;
}
/*
* Function: scsi_io_completion()
*
* Purpose: Completion processing for block device I/O requests.
*
* Arguments: cmd - command that is finished.
*
* Lock status: Assumed that no lock is held upon entry.
*
* Returns: Nothing
*
* Notes: This function is matched in terms of capabilities to
* the function that created the scatter-gather list.
* In other words, if there are no bounce buffers
* (the normal case for most drivers), we don't need
* the logic to deal with cleaning up afterwards.
*
* We must do one of several things here:
*
* a) Call scsi_end_request. This will finish off the
* specified number of sectors. If we are done, the
* command block will be released, and the queue
* function will be goosed. If we are not done, then
* scsi_end_request will directly goose the queue.
*
* b) We can just use scsi_requeue_command() here. This would
* be used if we just wanted to retry, for example.
*/
void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes,
unsigned int block_bytes)
{
int result = cmd->result;
int this_count = cmd->bufflen;
request_queue_t *q = cmd->device->request_queue;
struct request *req = cmd->request;
int clear_errors = 1;
struct scsi_sense_hdr sshdr;
int sense_valid = 0;
int sense_deferred = 0;
if (blk_complete_barrier_rq(q, req, good_bytes >> 9))
return;
/*
* Free up any indirection buffers we allocated for DMA purposes.
* For the case of a READ, we need to copy the data out of the
* bounce buffer and into the real buffer.
*/
if (cmd->use_sg)
scsi_free_sgtable(cmd->buffer, cmd->sglist_len);
else if (cmd->buffer != req->buffer) {
if (rq_data_dir(req) == READ) {
unsigned long flags;
char *to = bio_kmap_irq(req->bio, &flags);
memcpy(to, cmd->buffer, cmd->bufflen);
bio_kunmap_irq(to, &flags);
}
kfree(cmd->buffer);
}
if (result) {
sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
if (sense_valid)
sense_deferred = scsi_sense_is_deferred(&sshdr);
}
if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
req->errors = result;
if (result) {
clear_errors = 0;
if (sense_valid && req->sense) {
/*
* SG_IO wants current and deferred errors
*/
int len = 8 + cmd->sense_buffer[7];
if (len > SCSI_SENSE_BUFFERSIZE)
len = SCSI_SENSE_BUFFERSIZE;
memcpy(req->sense, cmd->sense_buffer, len);
req->sense_len = len;
}
} else
req->data_len = cmd->resid;
}
/*
* Zero these out. They now point to freed memory, and it is
* dangerous to hang onto the pointers.
*/
cmd->buffer = NULL;
cmd->bufflen = 0;
cmd->request_buffer = NULL;
cmd->request_bufflen = 0;
/*
* Next deal with any sectors which we were able to correctly
* handle.
*/
if (good_bytes >= 0) {
SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",
req->nr_sectors, good_bytes));
SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
if (clear_errors)
req->errors = 0;
/*
* If multiple sectors are requested in one buffer, then
* they will have been finished off by the first command.
* If not, then we have a multi-buffer command.
*
* If block_bytes != 0, it means we had a medium error
* of some sort, and that we want to mark some number of
* sectors as not uptodate. Thus we want to inhibit
* requeueing right here - we will requeue down below
* when we handle the bad sectors.
*/
cmd = scsi_end_request(cmd, 1, good_bytes, result == 0);
/*
* If the command completed without error, then either finish off the
* rest of the command, or start a new one.
*/
if (result == 0 || cmd == NULL ) {
return;
}
}
/*
* Now, if we were good little boys and girls, Santa left us a request
* sense buffer. We can extract information from this, so we
* can choose a block to remap, etc.
*/
if (sense_valid && !sense_deferred) {
switch (sshdr.sense_key) {
case UNIT_ATTENTION:
if (cmd->device->removable) {
/* detected disc change. set a bit
* and quietly refuse further access.
*/
cmd->device->changed = 1;
cmd = scsi_end_request(cmd, 0,
this_count, 1);
return;
} else {
/*
* Must have been a power glitch, or a
* bus reset. Could not have been a
* media change, so we just retry the
* request and see what happens.
*/
scsi_requeue_command(q, cmd);
return;
}
break;
case ILLEGAL_REQUEST:
/*
* If we had an ILLEGAL REQUEST returned, then we may
* have performed an unsupported command. The only
* thing this should be would be a ten byte read where
* only a six byte read was supported. Also, on a
* system where READ CAPACITY failed, we may have read
* past the end of the disk.
*/
if (cmd->device->use_10_for_rw &&
(cmd->cmnd[0] == READ_10 ||
cmd->cmnd[0] == WRITE_10)) {
cmd->device->use_10_for_rw = 0;
/*
* This will cause a retry with a 6-byte
* command.
*/
scsi_requeue_command(q, cmd);
result = 0;
} else {
cmd = scsi_end_request(cmd, 0, this_count, 1);
return;
}
break;
case NOT_READY:
/*
* If the device is in the process of becoming ready,
* retry.
*/
if (sshdr.asc == 0x04 && sshdr.ascq == 0x01) {
scsi_requeue_command(q, cmd);
return;
}
printk(KERN_INFO "Device %s not ready.\n",
req->rq_disk ? req->rq_disk->disk_name : "");
cmd = scsi_end_request(cmd, 0, this_count, 1);
return;
case VOLUME_OVERFLOW:
printk(KERN_INFO "Volume overflow <%d %d %d %d> CDB: ",
cmd->device->host->host_no,
(int)cmd->device->channel,
(int)cmd->device->id, (int)cmd->device->lun);
__scsi_print_command(cmd->data_cmnd);
scsi_print_sense("", cmd);
cmd = scsi_end_request(cmd, 0, block_bytes, 1);
return;
default:
break;
}
} /* driver byte != 0 */
if (host_byte(result) == DID_RESET) {
/*
* Third party bus reset or reset for error
* recovery reasons. Just retry the request
* and see what happens.
*/
scsi_requeue_command(q, cmd);
return;
}
if (result) {
printk(KERN_INFO "SCSI error : <%d %d %d %d> return code "
"= 0x%x\n", cmd->device->host->host_no,
cmd->device->channel,
cmd->device->id,
cmd->device->lun, result);
if (driver_byte(result) & DRIVER_SENSE)
scsi_print_sense("", cmd);
/*
* Mark a single buffer as not uptodate. Queue the remainder.
* We sometimes get this cruft in the event that a medium error
* isn't properly reported.
*/
block_bytes = req->hard_cur_sectors << 9;
if (!block_bytes)
block_bytes = req->data_len;
cmd = scsi_end_request(cmd, 0, block_bytes, 1);
}
}
EXPORT_SYMBOL(scsi_io_completion);
/*
* Function: scsi_init_io()
*
* Purpose: SCSI I/O initialize function.
*
* Arguments: cmd - Command descriptor we wish to initialize
*
* Returns: 0 on success
* BLKPREP_DEFER if the failure is retryable
* BLKPREP_KILL if the failure is fatal
*/
static int scsi_init_io(struct scsi_cmnd *cmd)
{
struct request *req = cmd->request;
struct scatterlist *sgpnt;
int count;
/*
* if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer
*/
if ((req->flags & REQ_BLOCK_PC) && !req->bio) {
cmd->request_bufflen = req->data_len;
cmd->request_buffer = req->data;
req->buffer = req->data;
cmd->use_sg = 0;
return 0;
}
/*
* we used to not use scatter-gather for single segment request,
* but now we do (it makes highmem I/O easier to support without
* kmapping pages)
*/
cmd->use_sg = req->nr_phys_segments;
/*
* if sg table allocation fails, requeue request later.
*/
sgpnt = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
if (unlikely(!sgpnt)) {
req->flags |= REQ_SPECIAL;
return BLKPREP_DEFER;
}
cmd->request_buffer = (char *) sgpnt;
cmd->request_bufflen = req->nr_sectors << 9;
if (blk_pc_request(req))
cmd->request_bufflen = req->data_len;
req->buffer = NULL;
/*
* Next, walk the list, and fill in the addresses and sizes of
* each segment.
*/
count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
/*
* mapped well, send it off
*/
if (likely(count <= cmd->use_sg)) {
cmd->use_sg = count;
return 0;
}
printk(KERN_ERR "Incorrect number of segments after building list\n");
printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg);
printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors,
req->current_nr_sectors);
/* release the command and kill it */
scsi_release_buffers(cmd);
scsi_put_command(cmd);
return BLKPREP_KILL;
}
static int scsi_prepare_flush_fn(request_queue_t *q, struct request *rq)
{
struct scsi_device *sdev = q->queuedata;
struct scsi_driver *drv;
if (sdev->sdev_state == SDEV_RUNNING) {
drv = *(struct scsi_driver **) rq->rq_disk->private_data;
if (drv->prepare_flush)
return drv->prepare_flush(q, rq);
}
return 0;
}
static void scsi_end_flush_fn(request_queue_t *q, struct request *rq)
{
struct scsi_device *sdev = q->queuedata;
struct request *flush_rq = rq->end_io_data;
struct scsi_driver *drv;
if (flush_rq->errors) {
printk("scsi: barrier error, disabling flush support\n");
blk_queue_ordered(q, QUEUE_ORDERED_NONE);
}
if (sdev->sdev_state == SDEV_RUNNING) {
drv = *(struct scsi_driver **) rq->rq_disk->private_data;
drv->end_flush(q, rq);
}
}
static int scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
sector_t *error_sector)
{
struct scsi_device *sdev = q->queuedata;
struct scsi_driver *drv;
if (sdev->sdev_state != SDEV_RUNNING)
return -ENXIO;
drv = *(struct scsi_driver **) disk->private_data;
if (drv->issue_flush)
return drv->issue_flush(&sdev->sdev_gendev, error_sector);
return -EOPNOTSUPP;
}
static int scsi_prep_fn(struct request_queue *q, struct request *req)
{
struct scsi_device *sdev = q->queuedata;
struct scsi_cmnd *cmd;
int specials_only = 0;
/*
* Just check to see if the device is online. If it isn't, we
* refuse to process any commands. The device must be brought
* online before trying any recovery commands
*/
if (unlikely(!scsi_device_online(sdev))) {
printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
sdev->host->host_no, sdev->id, sdev->lun);
return BLKPREP_KILL;
}
if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
/* OK, we're not in a running state don't prep
* user commands */
if (sdev->sdev_state == SDEV_DEL) {
/* Device is fully deleted, no commands
* at all allowed down */
printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to dead device\n",
sdev->host->host_no, sdev->id, sdev->lun);
return BLKPREP_KILL;
}
/* OK, we only allow special commands (i.e. not
* user initiated ones */
specials_only = sdev->sdev_state;
}
/*
* Find the actual device driver associated with this command.
* The SPECIAL requests are things like character device or
* ioctls, which did not originate from ll_rw_blk. Note that
* the special field is also used to indicate the cmd for
* the remainder of a partially fulfilled request that can
* come up when there is a medium error. We have to treat
* these two cases differently. We differentiate by looking
* at request->cmd, as this tells us the real story.
*/
if (req->flags & REQ_SPECIAL) {
struct scsi_request *sreq = req->special;
if (sreq->sr_magic == SCSI_REQ_MAGIC) {
cmd = scsi_get_command(sreq->sr_device, GFP_ATOMIC);
if (unlikely(!cmd))
goto defer;
scsi_init_cmd_from_req(cmd, sreq);
} else
cmd = req->special;
} else if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
if(unlikely(specials_only)) {
if(specials_only == SDEV_QUIESCE ||
specials_only == SDEV_BLOCK)
return BLKPREP_DEFER;
printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to device being removed\n",
sdev->host->host_no, sdev->id, sdev->lun);
return BLKPREP_KILL;
}
/*
* Now try and find a command block that we can use.
*/
if (!req->special) {
cmd = scsi_get_command(sdev, GFP_ATOMIC);
if (unlikely(!cmd))
goto defer;
} else
cmd = req->special;
/* pull a tag out of the request if we have one */
cmd->tag = req->tag;
} else {
blk_dump_rq_flags(req, "SCSI bad req");
return BLKPREP_KILL;
}
/* note the overloading of req->special. When the tag
* is active it always means cmd. If the tag goes
* back for re-queueing, it may be reset */
req->special = cmd;
cmd->request = req;
/*
* FIXME: drop the lock here because the functions below
* expect to be called without the queue lock held. Also,
* previously, we dequeued the request before dropping the
* lock. We hope REQ_STARTED prevents anything untoward from
* happening now.
*/
if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
struct scsi_driver *drv;
int ret;
/*
* This will do a couple of things:
* 1) Fill in the actual SCSI command.
* 2) Fill in any other upper-level specific fields
* (timeout).
*
* If this returns 0, it means that the request failed
* (reading past end of disk, reading offline device,
* etc). This won't actually talk to the device, but
* some kinds of consistency checking may cause the
* request to be rejected immediately.
*/
/*
* This sets up the scatter-gather table (allocating if
* required).
*/
ret = scsi_init_io(cmd);
if (ret) /* BLKPREP_KILL return also releases the command */
return ret;
/*
* Initialize the actual SCSI command for this request.
*/
drv = *(struct scsi_driver **)req->rq_disk->private_data;
if (unlikely(!drv->init_command(cmd))) {
scsi_release_buffers(cmd);
scsi_put_command(cmd);
return BLKPREP_KILL;
}
}
/*
* The request is now prepped, no need to come back here
*/
req->flags |= REQ_DONTPREP;
return BLKPREP_OK;
defer:
/* If we defer, the elv_next_request() returns NULL, but the
* queue must be restarted, so we plug here if no returning
* command will automatically do that. */
if (sdev->device_busy == 0)
blk_plug_device(q);
return BLKPREP_DEFER;
}
/*
* scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
* return 0.
*
* Called with the queue_lock held.
*/
static inline int scsi_dev_queue_ready(struct request_queue *q,
struct scsi_device *sdev)
{
if (sdev->device_busy >= sdev->queue_depth)
return 0;
if (sdev->device_busy == 0 && sdev->device_blocked) {
/*
* unblock after device_blocked iterates to zero
*/
if (--sdev->device_blocked == 0) {
SCSI_LOG_MLQUEUE(3,
printk("scsi%d (%d:%d) unblocking device at"
" zero depth\n", sdev->host->host_no,
sdev->id, sdev->lun));
} else {
blk_plug_device(q);
return 0;
}
}
if (sdev->device_blocked)
return 0;
return 1;
}
/*
* scsi_host_queue_ready: if we can send requests to shost, return 1 else
* return 0. We must end up running the queue again whenever 0 is
* returned, else IO can hang.
*
* Called with host_lock held.
*/
static inline int scsi_host_queue_ready(struct request_queue *q,
struct Scsi_Host *shost,
struct scsi_device *sdev)
{
if (test_bit(SHOST_RECOVERY, &shost->shost_state))
return 0;
if (shost->host_busy == 0 && shost->host_blocked) {
/*
* unblock after host_blocked iterates to zero
*/
if (--shost->host_blocked == 0) {
SCSI_LOG_MLQUEUE(3,
printk("scsi%d unblocking host at zero depth\n",
shost->host_no));
} else {
blk_plug_device(q);
return 0;
}
}
if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
shost->host_blocked || shost->host_self_blocked) {
if (list_empty(&sdev->starved_entry))
list_add_tail(&sdev->starved_entry, &shost->starved_list);
return 0;
}
/* We're OK to process the command, so we can't be starved */
if (!list_empty(&sdev->starved_entry))
list_del_init(&sdev->starved_entry);
return 1;
}
/*
* Kill requests for a dead device
*/
static void scsi_kill_requests(request_queue_t *q)
{
struct request *req;
while ((req = elv_next_request(q)) != NULL) {
blkdev_dequeue_request(req);
req->flags |= REQ_QUIET;
while (end_that_request_first(req, 0, req->nr_sectors))
;
end_that_request_last(req);
}
}
/*
* Function: scsi_request_fn()
*
* Purpose: Main strategy routine for SCSI.
*
* Arguments: q - Pointer to actual queue.
*
* Returns: Nothing
*
* Lock status: IO request lock assumed to be held when called.
*/
static void scsi_request_fn(struct request_queue *q)
{
struct scsi_device *sdev = q->queuedata;
struct Scsi_Host *shost;
struct scsi_cmnd *cmd;
struct request *req;
if (!sdev) {
printk("scsi: killing requests for dead queue\n");
scsi_kill_requests(q);
return;
}
if(!get_device(&sdev->sdev_gendev))
/* We must be tearing the block queue down already */
return;
/*
* To start with, we keep looping until the queue is empty, or until
* the host is no longer able to accept any more requests.
*/
shost = sdev->host;
while (!blk_queue_plugged(q)) {
int rtn;
/*
* get next queueable request. We do this early to make sure
* that the request is fully prepared even if we cannot
* accept it.
*/
req = elv_next_request(q);
if (!req || !scsi_dev_queue_ready(q, sdev))
break;
if (unlikely(!scsi_device_online(sdev))) {
printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
sdev->host->host_no, sdev->id, sdev->lun);
blkdev_dequeue_request(req);
req->flags |= REQ_QUIET;
while (end_that_request_first(req, 0, req->nr_sectors))
;
end_that_request_last(req);
continue;
}
/*
* Remove the request from the request list.
*/
if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
blkdev_dequeue_request(req);
sdev->device_busy++;
spin_unlock(q->queue_lock);
spin_lock(shost->host_lock);
if (!scsi_host_queue_ready(q, shost, sdev))
goto not_ready;
if (sdev->single_lun) {
if (scsi_target(sdev)->starget_sdev_user &&
scsi_target(sdev)->starget_sdev_user != sdev)
goto not_ready;
scsi_target(sdev)->starget_sdev_user = sdev;
}
shost->host_busy++;
/*
* XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
* take the lock again.
*/
spin_unlock_irq(shost->host_lock);
cmd = req->special;
if (unlikely(cmd == NULL)) {
printk(KERN_CRIT "impossible request in %s.\n"
"please mail a stack trace to "
"linux-scsi@vger.kernel.org",
__FUNCTION__);
BUG();
}
/*
* Finally, initialize any error handling parameters, and set up
* the timers for timeouts.
*/
scsi_init_cmd_errh(cmd);
/*
* Dispatch the command to the low-level driver.
*/
rtn = scsi_dispatch_cmd(cmd);
spin_lock_irq(q->queue_lock);
if(rtn) {
/* we're refusing the command; because of
* the way locks get dropped, we need to
* check here if plugging is required */
if(sdev->device_busy == 0)
blk_plug_device(q);
break;
}
}
goto out;
not_ready:
spin_unlock_irq(shost->host_lock);
/*
* lock q, handle tag, requeue req, and decrement device_busy. We
* must return with queue_lock held.
*
* Decrementing device_busy without checking it is OK, as all such
* cases (host limits or settings) should run the queue at some
* later time.
*/
spin_lock_irq(q->queue_lock);
blk_requeue_request(q, req);
sdev->device_busy--;
if(sdev->device_busy == 0)
blk_plug_device(q);
out:
/* must be careful here...if we trigger the ->remove() function
* we cannot be holding the q lock */
spin_unlock_irq(q->queue_lock);
put_device(&sdev->sdev_gendev);
spin_lock_irq(q->queue_lock);
}
u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
{
struct device *host_dev;
u64 bounce_limit = 0xffffffff;
if (shost->unchecked_isa_dma)
return BLK_BOUNCE_ISA;
/*
* Platforms with virtual-DMA translation
* hardware have no practical limit.
*/
if (!PCI_DMA_BUS_IS_PHYS)
return BLK_BOUNCE_ANY;
host_dev = scsi_get_device(shost);
if (host_dev && host_dev->dma_mask)
bounce_limit = *host_dev->dma_mask;
return bounce_limit;
}
EXPORT_SYMBOL(scsi_calculate_bounce_limit);
struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
{
struct Scsi_Host *shost = sdev->host;
struct request_queue *q;
q = blk_init_queue(scsi_request_fn, NULL);
if (!q)
return NULL;
blk_queue_prep_rq(q, scsi_prep_fn);
blk_queue_max_hw_segments(q, shost->sg_tablesize);
blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS);
blk_queue_max_sectors(q, shost->max_sectors);
blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
blk_queue_segment_boundary(q, shost->dma_boundary);
blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);
/*
* ordered tags are superior to flush ordering
*/
if (shost->ordered_tag)
blk_queue_ordered(q, QUEUE_ORDERED_TAG);
else if (shost->ordered_flush) {
blk_queue_ordered(q, QUEUE_ORDERED_FLUSH);
q->prepare_flush_fn = scsi_prepare_flush_fn;
q->end_flush_fn = scsi_end_flush_fn;
}
if (!shost->use_clustering)
clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
return q;
}
void scsi_free_queue(struct request_queue *q)
{
blk_cleanup_queue(q);
}
/*
* Function: scsi_block_requests()
*
* Purpose: Utility function used by low-level drivers to prevent further
* commands from being queued to the device.
*
* Arguments: shost - Host in question
*
* Returns: Nothing
*
* Lock status: No locks are assumed held.
*
* Notes: There is no timer nor any other means by which the requests
* get unblocked other than the low-level driver calling
* scsi_unblock_requests().
*/
void scsi_block_requests(struct Scsi_Host *shost)
{
shost->host_self_blocked = 1;
}
EXPORT_SYMBOL(scsi_block_requests);
/*
* Function: scsi_unblock_requests()
*
* Purpose: Utility function used by low-level drivers to allow further
* commands from being queued to the device.
*
* Arguments: shost - Host in question
*
* Returns: Nothing
*
* Lock status: No locks are assumed held.
*
* Notes: There is no timer nor any other means by which the requests
* get unblocked other than the low-level driver calling
* scsi_unblock_requests().
*
* This is done as an API function so that changes to the
* internals of the scsi mid-layer won't require wholesale
* changes to drivers that use this feature.
*/
void scsi_unblock_requests(struct Scsi_Host *shost)
{
shost->host_self_blocked = 0;
scsi_run_host_queues(shost);
}
EXPORT_SYMBOL(scsi_unblock_requests);
int __init scsi_init_queue(void)
{
int i;
for (i = 0; i < SG_MEMPOOL_NR; i++) {
struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
int size = sgp->size * sizeof(struct scatterlist);
sgp->slab = kmem_cache_create(sgp->name, size, 0,
SLAB_HWCACHE_ALIGN, NULL, NULL);
if (!sgp->slab) {
printk(KERN_ERR "SCSI: can't init sg slab %s\n",
sgp->name);
}
sgp->pool = mempool_create(SG_MEMPOOL_SIZE,
mempool_alloc_slab, mempool_free_slab,
sgp->slab);
if (!sgp->pool) {
printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
sgp->name);
}
}
return 0;
}
void scsi_exit_queue(void)
{
int i;
for (i = 0; i < SG_MEMPOOL_NR; i++) {
struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
mempool_destroy(sgp->pool);
kmem_cache_destroy(sgp->slab);
}
}
/**
* __scsi_mode_sense - issue a mode sense, falling back from 10 to
* six bytes if necessary.
* @sreq: SCSI request to fill in with the MODE_SENSE
* @dbd: set if mode sense will allow block descriptors to be returned
* @modepage: mode page being requested
* @buffer: request buffer (may not be smaller than eight bytes)
* @len: length of request buffer.
* @timeout: command timeout
* @retries: number of retries before failing
* @data: returns a structure abstracting the mode header data
*
* Returns zero if unsuccessful, or the header offset (either 4
* or 8 depending on whether a six or ten byte command was
* issued) if successful.
**/
int
__scsi_mode_sense(struct scsi_request *sreq, int dbd, int modepage,
unsigned char *buffer, int len, int timeout, int retries,
struct scsi_mode_data *data) {
unsigned char cmd[12];
int use_10_for_ms;
int header_length;
memset(data, 0, sizeof(*data));
memset(&cmd[0], 0, 12);
cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
cmd[2] = modepage;
retry:
use_10_for_ms = sreq->sr_device->use_10_for_ms;
if (use_10_for_ms) {
if (len < 8)
len = 8;
cmd[0] = MODE_SENSE_10;
cmd[8] = len;
header_length = 8;
} else {
if (len < 4)
len = 4;
cmd[0] = MODE_SENSE;
cmd[4] = len;
header_length = 4;
}
sreq->sr_cmd_len = 0;
memset(sreq->sr_sense_buffer, 0, sizeof(sreq->sr_sense_buffer));
sreq->sr_data_direction = DMA_FROM_DEVICE;
memset(buffer, 0, len);
scsi_wait_req(sreq, cmd, buffer, len, timeout, retries);
/* This code looks awful: what it's doing is making sure an
* ILLEGAL REQUEST sense return identifies the actual command
* byte as the problem. MODE_SENSE commands can return
* ILLEGAL REQUEST if the code page isn't supported */
if (use_10_for_ms && !scsi_status_is_good(sreq->sr_result) &&
(driver_byte(sreq->sr_result) & DRIVER_SENSE)) {
struct scsi_sense_hdr sshdr;
if (scsi_request_normalize_sense(sreq, &sshdr)) {
if ((sshdr.sense_key == ILLEGAL_REQUEST) &&
(sshdr.asc == 0x20) && (sshdr.ascq == 0)) {
/*
* Invalid command operation code
*/
sreq->sr_device->use_10_for_ms = 0;
goto retry;
}
}
}
if(scsi_status_is_good(sreq->sr_result)) {
data->header_length = header_length;
if(use_10_for_ms) {
data->length = buffer[0]*256 + buffer[1] + 2;
data->medium_type = buffer[2];
data->device_specific = buffer[3];
data->longlba = buffer[4] & 0x01;
data->block_descriptor_length = buffer[6]*256
+ buffer[7];
} else {
data->length = buffer[0] + 1;
data->medium_type = buffer[1];
data->device_specific = buffer[2];
data->block_descriptor_length = buffer[3];
}
}
return sreq->sr_result;
}
EXPORT_SYMBOL(__scsi_mode_sense);
/**
* scsi_mode_sense - issue a mode sense, falling back from 10 to
* six bytes if necessary.
* @sdev: scsi device to send command to.
* @dbd: set if mode sense will disable block descriptors in the return
* @modepage: mode page being requested
* @buffer: request buffer (may not be smaller than eight bytes)
* @len: length of request buffer.
* @timeout: command timeout
* @retries: number of retries before failing
*
* Returns zero if unsuccessful, or the header offset (either 4
* or 8 depending on whether a six or ten byte command was
* issued) if successful.
**/
int
scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
unsigned char *buffer, int len, int timeout, int retries,
struct scsi_mode_data *data)
{
struct scsi_request *sreq = scsi_allocate_request(sdev, GFP_KERNEL);
int ret;
if (!sreq)
return -1;
ret = __scsi_mode_sense(sreq, dbd, modepage, buffer, len,
timeout, retries, data);
scsi_release_request(sreq);
return ret;
}
EXPORT_SYMBOL(scsi_mode_sense);
int
scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
{
struct scsi_request *sreq;
char cmd[] = {
TEST_UNIT_READY, 0, 0, 0, 0, 0,
};
int result;
sreq = scsi_allocate_request(sdev, GFP_KERNEL);
if (!sreq)
return -ENOMEM;
sreq->sr_data_direction = DMA_NONE;
scsi_wait_req(sreq, cmd, NULL, 0, timeout, retries);
if ((driver_byte(sreq->sr_result) & DRIVER_SENSE) && sdev->removable) {
struct scsi_sense_hdr sshdr;
if ((scsi_request_normalize_sense(sreq, &sshdr)) &&
((sshdr.sense_key == UNIT_ATTENTION) ||
(sshdr.sense_key == NOT_READY))) {
sdev->changed = 1;
sreq->sr_result = 0;
}
}
result = sreq->sr_result;
scsi_release_request(sreq);
return result;
}
EXPORT_SYMBOL(scsi_test_unit_ready);
/**
* scsi_device_set_state - Take the given device through the device
* state model.
* @sdev: scsi device to change the state of.
* @state: state to change to.
*
* Returns zero if unsuccessful or an error if the requested
* transition is illegal.
**/
int
scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
{
enum scsi_device_state oldstate = sdev->sdev_state;
if (state == oldstate)
return 0;
switch (state) {
case SDEV_CREATED:
/* There are no legal states that come back to
* created. This is the manually initialised start
* state */
goto illegal;
case SDEV_RUNNING:
switch (oldstate) {
case SDEV_CREATED:
case SDEV_OFFLINE:
case SDEV_QUIESCE:
case SDEV_BLOCK:
break;
default:
goto illegal;
}
break;
case SDEV_QUIESCE:
switch (oldstate) {
case SDEV_RUNNING:
case SDEV_OFFLINE:
break;
default:
goto illegal;
}
break;
case SDEV_OFFLINE:
switch (oldstate) {
case SDEV_CREATED:
case SDEV_RUNNING:
case SDEV_QUIESCE:
case SDEV_BLOCK:
break;
default:
goto illegal;
}
break;
case SDEV_BLOCK:
switch (oldstate) {
case SDEV_CREATED:
case SDEV_RUNNING:
break;
default:
goto illegal;
}
break;
case SDEV_CANCEL:
switch (oldstate) {
case SDEV_CREATED:
case SDEV_RUNNING:
case SDEV_OFFLINE:
case SDEV_BLOCK:
break;
default:
goto illegal;
}
break;
case SDEV_DEL:
switch (oldstate) {
case SDEV_CANCEL:
break;
default:
goto illegal;
}
break;
}
sdev->sdev_state = state;
return 0;
illegal:
SCSI_LOG_ERROR_RECOVERY(1,
dev_printk(KERN_ERR, &sdev->sdev_gendev,
"Illegal state transition %s->%s\n",
scsi_device_state_name(oldstate),
scsi_device_state_name(state))
);
return -EINVAL;
}
EXPORT_SYMBOL(scsi_device_set_state);
/**
* scsi_device_quiesce - Block user issued commands.
* @sdev: scsi device to quiesce.
*
* This works by trying to transition to the SDEV_QUIESCE state
* (which must be a legal transition). When the device is in this
* state, only special requests will be accepted, all others will
* be deferred. Since special requests may also be requeued requests,
* a successful return doesn't guarantee the device will be
* totally quiescent.
*
* Must be called with user context, may sleep.
*
* Returns zero if unsuccessful or an error if not.
**/
int
scsi_device_quiesce(struct scsi_device *sdev)
{
int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
if (err)
return err;
scsi_run_queue(sdev->request_queue);
while (sdev->device_busy) {
msleep_interruptible(200);
scsi_run_queue(sdev->request_queue);
}
return 0;
}
EXPORT_SYMBOL(scsi_device_quiesce);
/**
* scsi_device_resume - Restart user issued commands to a quiesced device.
* @sdev: scsi device to resume.
*
* Moves the device from quiesced back to running and restarts the
* queues.
*
* Must be called with user context, may sleep.
**/
void
scsi_device_resume(struct scsi_device *sdev)
{
if(scsi_device_set_state(sdev, SDEV_RUNNING))
return;
scsi_run_queue(sdev->request_queue);
}
EXPORT_SYMBOL(scsi_device_resume);
static void
device_quiesce_fn(struct scsi_device *sdev, void *data)
{
scsi_device_quiesce(sdev);
}
void
scsi_target_quiesce(struct scsi_target *starget)
{
starget_for_each_device(starget, NULL, device_quiesce_fn);
}
EXPORT_SYMBOL(scsi_target_quiesce);
static void
device_resume_fn(struct scsi_device *sdev, void *data)
{
scsi_device_resume(sdev);
}
void
scsi_target_resume(struct scsi_target *starget)
{
starget_for_each_device(starget, NULL, device_resume_fn);
}
EXPORT_SYMBOL(scsi_target_resume);
/**
* scsi_internal_device_block - internal function to put a device
* temporarily into the SDEV_BLOCK state
* @sdev: device to block
*
* Block request made by scsi lld's to temporarily stop all
* scsi commands on the specified device. Called from interrupt
* or normal process context.
*
* Returns zero if successful or error if not
*
* Notes:
* This routine transitions the device to the SDEV_BLOCK state
* (which must be a legal transition). When the device is in this
* state, all commands are deferred until the scsi lld reenables
* the device with scsi_device_unblock or device_block_tmo fires.
* This routine assumes the host_lock is held on entry.
**/
int
scsi_internal_device_block(struct scsi_device *sdev)
{
request_queue_t *q = sdev->request_queue;
unsigned long flags;
int err = 0;
err = scsi_device_set_state(sdev, SDEV_BLOCK);
if (err)
return err;
/*
* The device has transitioned to SDEV_BLOCK. Stop the
* block layer from calling the midlayer with this device's
* request queue.
*/
spin_lock_irqsave(q->queue_lock, flags);
blk_stop_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
return 0;
}
EXPORT_SYMBOL_GPL(scsi_internal_device_block);
/**
* scsi_internal_device_unblock - resume a device after a block request
* @sdev: device to resume
*
* Called by scsi lld's or the midlayer to restart the device queue
* for the previously suspended scsi device. Called from interrupt or
* normal process context.
*
* Returns zero if successful or error if not.
*
* Notes:
* This routine transitions the device to the SDEV_RUNNING state
* (which must be a legal transition) allowing the midlayer to
* goose the queue for this device. This routine assumes the
* host_lock is held upon entry.
**/
int
scsi_internal_device_unblock(struct scsi_device *sdev)
{
request_queue_t *q = sdev->request_queue;
int err;
unsigned long flags;
/*
* Try to transition the scsi device to SDEV_RUNNING
* and goose the device queue if successful.
*/
err = scsi_device_set_state(sdev, SDEV_RUNNING);
if (err)
return err;
spin_lock_irqsave(q->queue_lock, flags);
blk_start_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
return 0;
}
EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
static void
device_block(struct scsi_device *sdev, void *data)
{
scsi_internal_device_block(sdev);
}
static int
target_block(struct device *dev, void *data)
{
if (scsi_is_target_device(dev))
starget_for_each_device(to_scsi_target(dev), NULL,
device_block);
return 0;
}
void
scsi_target_block(struct device *dev)
{
if (scsi_is_target_device(dev))
starget_for_each_device(to_scsi_target(dev), NULL,
device_block);
else
device_for_each_child(dev, NULL, target_block);
}
EXPORT_SYMBOL_GPL(scsi_target_block);
static void
device_unblock(struct scsi_device *sdev, void *data)
{
scsi_internal_device_unblock(sdev);
}
static int
target_unblock(struct device *dev, void *data)
{
if (scsi_is_target_device(dev))
starget_for_each_device(to_scsi_target(dev), NULL,
device_unblock);
return 0;
}
void
scsi_target_unblock(struct device *dev)
{
if (scsi_is_target_device(dev))
starget_for_each_device(to_scsi_target(dev), NULL,
device_unblock);
else
device_for_each_child(dev, NULL, target_unblock);
}
EXPORT_SYMBOL_GPL(scsi_target_unblock);
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