linux/include/scsi/scsi_cmnd.h
Martin K. Petersen 18a4d0a22e [SCSI] Handle disk devices which can not process medium access commands
We have experienced several devices which fail in a fashion we do not
currently handle gracefully in SCSI. After a failure these devices will
respond to the SCSI primary command set (INQUIRY, TEST UNIT READY, etc.)
but any command accessing the storage medium will time out.

The following patch adds an callback that can be used by upper level
drivers to inspect the results of an error handling command. This in
turn has been used to implement additional checking in the SCSI disk
driver.

If a medium access command fails twice but TEST UNIT READY succeeds both
times in the subsequent error handling we will offline the device. The
maximum number of failed commands required to take a device offline can
be tweaked in sysfs.

Also add a new error flag to scsi_debug which allows this scenario to be
easily reproduced.

[jejb: fix up integer parsing to use kstrtouint]
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
2012-02-19 10:14:52 -06:00

312 lines
8.5 KiB
C

#ifndef _SCSI_SCSI_CMND_H
#define _SCSI_SCSI_CMND_H
#include <linux/dma-mapping.h>
#include <linux/blkdev.h>
#include <linux/list.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/scatterlist.h>
struct Scsi_Host;
struct scsi_device;
struct scsi_driver;
/*
* MAX_COMMAND_SIZE is:
* The longest fixed-length SCSI CDB as per the SCSI standard.
* fixed-length means: commands that their size can be determined
* by their opcode and the CDB does not carry a length specifier, (unlike
* the VARIABLE_LENGTH_CMD(0x7f) command). This is actually not exactly
* true and the SCSI standard also defines extended commands and
* vendor specific commands that can be bigger than 16 bytes. The kernel
* will support these using the same infrastructure used for VARLEN CDB's.
* So in effect MAX_COMMAND_SIZE means the maximum size command scsi-ml
* supports without specifying a cmd_len by ULD's
*/
#define MAX_COMMAND_SIZE 16
#if (MAX_COMMAND_SIZE > BLK_MAX_CDB)
# error MAX_COMMAND_SIZE can not be bigger than BLK_MAX_CDB
#endif
struct scsi_data_buffer {
struct sg_table table;
unsigned length;
int resid;
};
/* embedded in scsi_cmnd */
struct scsi_pointer {
char *ptr; /* data pointer */
int this_residual; /* left in this buffer */
struct scatterlist *buffer; /* which buffer */
int buffers_residual; /* how many buffers left */
dma_addr_t dma_handle;
volatile int Status;
volatile int Message;
volatile int have_data_in;
volatile int sent_command;
volatile int phase;
};
struct scsi_cmnd {
struct scsi_device *device;
struct list_head list; /* scsi_cmnd participates in queue lists */
struct list_head eh_entry; /* entry for the host eh_cmd_q */
int eh_eflags; /* Used by error handlr */
/*
* A SCSI Command is assigned a nonzero serial_number before passed
* to the driver's queue command function. The serial_number is
* cleared when scsi_done is entered indicating that the command
* has been completed. It is a bug for LLDDs to use this number
* for purposes other than printk (and even that is only useful
* for debugging).
*/
unsigned long serial_number;
/*
* This is set to jiffies as it was when the command was first
* allocated. It is used to time how long the command has
* been outstanding
*/
unsigned long jiffies_at_alloc;
int retries;
int allowed;
unsigned char prot_op;
unsigned char prot_type;
unsigned short cmd_len;
enum dma_data_direction sc_data_direction;
/* These elements define the operation we are about to perform */
unsigned char *cmnd;
/* These elements define the operation we ultimately want to perform */
struct scsi_data_buffer sdb;
struct scsi_data_buffer *prot_sdb;
unsigned underflow; /* Return error if less than
this amount is transferred */
unsigned transfersize; /* How much we are guaranteed to
transfer with each SCSI transfer
(ie, between disconnect /
reconnects. Probably == sector
size */
struct request *request; /* The command we are
working on */
#define SCSI_SENSE_BUFFERSIZE 96
unsigned char *sense_buffer;
/* obtained by REQUEST SENSE when
* CHECK CONDITION is received on original
* command (auto-sense) */
/* Low-level done function - can be used by low-level driver to point
* to completion function. Not used by mid/upper level code. */
void (*scsi_done) (struct scsi_cmnd *);
/*
* The following fields can be written to by the host specific code.
* Everything else should be left alone.
*/
struct scsi_pointer SCp; /* Scratchpad used by some host adapters */
unsigned char *host_scribble; /* The host adapter is allowed to
* call scsi_malloc and get some memory
* and hang it here. The host adapter
* is also expected to call scsi_free
* to release this memory. (The memory
* obtained by scsi_malloc is guaranteed
* to be at an address < 16Mb). */
int result; /* Status code from lower level driver */
unsigned char tag; /* SCSI-II queued command tag */
};
static inline struct scsi_driver *scsi_cmd_to_driver(struct scsi_cmnd *cmd)
{
return *(struct scsi_driver **)cmd->request->rq_disk->private_data;
}
extern struct scsi_cmnd *scsi_get_command(struct scsi_device *, gfp_t);
extern struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *, gfp_t);
extern void scsi_put_command(struct scsi_cmnd *);
extern void __scsi_put_command(struct Scsi_Host *, struct scsi_cmnd *,
struct device *);
extern void scsi_finish_command(struct scsi_cmnd *cmd);
extern void *scsi_kmap_atomic_sg(struct scatterlist *sg, int sg_count,
size_t *offset, size_t *len);
extern void scsi_kunmap_atomic_sg(void *virt);
extern int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask);
extern void scsi_release_buffers(struct scsi_cmnd *cmd);
extern int scsi_dma_map(struct scsi_cmnd *cmd);
extern void scsi_dma_unmap(struct scsi_cmnd *cmd);
struct scsi_cmnd *scsi_allocate_command(gfp_t gfp_mask);
void scsi_free_command(gfp_t gfp_mask, struct scsi_cmnd *cmd);
static inline unsigned scsi_sg_count(struct scsi_cmnd *cmd)
{
return cmd->sdb.table.nents;
}
static inline struct scatterlist *scsi_sglist(struct scsi_cmnd *cmd)
{
return cmd->sdb.table.sgl;
}
static inline unsigned scsi_bufflen(struct scsi_cmnd *cmd)
{
return cmd->sdb.length;
}
static inline void scsi_set_resid(struct scsi_cmnd *cmd, int resid)
{
cmd->sdb.resid = resid;
}
static inline int scsi_get_resid(struct scsi_cmnd *cmd)
{
return cmd->sdb.resid;
}
#define scsi_for_each_sg(cmd, sg, nseg, __i) \
for_each_sg(scsi_sglist(cmd), sg, nseg, __i)
static inline int scsi_bidi_cmnd(struct scsi_cmnd *cmd)
{
return blk_bidi_rq(cmd->request) &&
(cmd->request->next_rq->special != NULL);
}
static inline struct scsi_data_buffer *scsi_in(struct scsi_cmnd *cmd)
{
return scsi_bidi_cmnd(cmd) ?
cmd->request->next_rq->special : &cmd->sdb;
}
static inline struct scsi_data_buffer *scsi_out(struct scsi_cmnd *cmd)
{
return &cmd->sdb;
}
static inline int scsi_sg_copy_from_buffer(struct scsi_cmnd *cmd,
void *buf, int buflen)
{
return sg_copy_from_buffer(scsi_sglist(cmd), scsi_sg_count(cmd),
buf, buflen);
}
static inline int scsi_sg_copy_to_buffer(struct scsi_cmnd *cmd,
void *buf, int buflen)
{
return sg_copy_to_buffer(scsi_sglist(cmd), scsi_sg_count(cmd),
buf, buflen);
}
/*
* The operations below are hints that tell the controller driver how
* to handle I/Os with DIF or similar types of protection information.
*/
enum scsi_prot_operations {
/* Normal I/O */
SCSI_PROT_NORMAL = 0,
/* OS-HBA: Protected, HBA-Target: Unprotected */
SCSI_PROT_READ_INSERT,
SCSI_PROT_WRITE_STRIP,
/* OS-HBA: Unprotected, HBA-Target: Protected */
SCSI_PROT_READ_STRIP,
SCSI_PROT_WRITE_INSERT,
/* OS-HBA: Protected, HBA-Target: Protected */
SCSI_PROT_READ_PASS,
SCSI_PROT_WRITE_PASS,
};
static inline void scsi_set_prot_op(struct scsi_cmnd *scmd, unsigned char op)
{
scmd->prot_op = op;
}
static inline unsigned char scsi_get_prot_op(struct scsi_cmnd *scmd)
{
return scmd->prot_op;
}
/*
* The controller usually does not know anything about the target it
* is communicating with. However, when DIX is enabled the controller
* must be know target type so it can verify the protection
* information passed along with the I/O.
*/
enum scsi_prot_target_type {
SCSI_PROT_DIF_TYPE0 = 0,
SCSI_PROT_DIF_TYPE1,
SCSI_PROT_DIF_TYPE2,
SCSI_PROT_DIF_TYPE3,
};
static inline void scsi_set_prot_type(struct scsi_cmnd *scmd, unsigned char type)
{
scmd->prot_type = type;
}
static inline unsigned char scsi_get_prot_type(struct scsi_cmnd *scmd)
{
return scmd->prot_type;
}
static inline sector_t scsi_get_lba(struct scsi_cmnd *scmd)
{
return blk_rq_pos(scmd->request);
}
static inline unsigned scsi_prot_sg_count(struct scsi_cmnd *cmd)
{
return cmd->prot_sdb ? cmd->prot_sdb->table.nents : 0;
}
static inline struct scatterlist *scsi_prot_sglist(struct scsi_cmnd *cmd)
{
return cmd->prot_sdb ? cmd->prot_sdb->table.sgl : NULL;
}
static inline struct scsi_data_buffer *scsi_prot(struct scsi_cmnd *cmd)
{
return cmd->prot_sdb;
}
#define scsi_for_each_prot_sg(cmd, sg, nseg, __i) \
for_each_sg(scsi_prot_sglist(cmd), sg, nseg, __i)
static inline void set_msg_byte(struct scsi_cmnd *cmd, char status)
{
cmd->result = (cmd->result & 0xffff00ff) | (status << 8);
}
static inline void set_host_byte(struct scsi_cmnd *cmd, char status)
{
cmd->result = (cmd->result & 0xff00ffff) | (status << 16);
}
static inline void set_driver_byte(struct scsi_cmnd *cmd, char status)
{
cmd->result = (cmd->result & 0x00ffffff) | (status << 24);
}
#endif /* _SCSI_SCSI_CMND_H */