forked from Minki/linux
cdb8c2a6d8
The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
160 lines
5.2 KiB
C
160 lines
5.2 KiB
C
#ifndef _SCSI_SCSI_CMND_H
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#define _SCSI_SCSI_CMND_H
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#include <linux/dma-mapping.h>
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#include <linux/list.h>
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#include <linux/types.h>
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#include <linux/timer.h>
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struct request;
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struct scatterlist;
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struct scsi_device;
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struct scsi_request;
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/* embedded in scsi_cmnd */
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struct scsi_pointer {
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char *ptr; /* data pointer */
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int this_residual; /* left in this buffer */
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struct scatterlist *buffer; /* which buffer */
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int buffers_residual; /* how many buffers left */
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dma_addr_t dma_handle;
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volatile int Status;
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volatile int Message;
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volatile int have_data_in;
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volatile int sent_command;
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volatile int phase;
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};
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struct scsi_cmnd {
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int sc_magic;
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struct scsi_device *device;
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struct scsi_request *sc_request;
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struct list_head list; /* scsi_cmnd participates in queue lists */
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struct list_head eh_entry; /* entry for the host eh_cmd_q */
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int eh_eflags; /* Used by error handlr */
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void (*done) (struct scsi_cmnd *); /* Mid-level done function */
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/*
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* A SCSI Command is assigned a nonzero serial_number before passed
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* to the driver's queue command function. The serial_number is
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* cleared when scsi_done is entered indicating that the command
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* has been completed. It currently doesn't have much use other
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* than printk's. Some lldd's use this number for other purposes.
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* It's almost certain that such usages are either incorrect or
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* meaningless. Please kill all usages other than printk's. Also,
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* as this number is always identical to ->pid, please convert
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* printk's to use ->pid, so that we can kill this field.
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*/
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unsigned long serial_number;
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/*
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* This is set to jiffies as it was when the command was first
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* allocated. It is used to time how long the command has
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* been outstanding
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*/
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unsigned long jiffies_at_alloc;
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int retries;
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int allowed;
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int timeout_per_command;
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unsigned char cmd_len;
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unsigned char old_cmd_len;
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enum dma_data_direction sc_data_direction;
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enum dma_data_direction sc_old_data_direction;
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/* These elements define the operation we are about to perform */
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#define MAX_COMMAND_SIZE 16
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unsigned char cmnd[MAX_COMMAND_SIZE];
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unsigned request_bufflen; /* Actual request size */
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struct timer_list eh_timeout; /* Used to time out the command. */
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void *request_buffer; /* Actual requested buffer */
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/* These elements define the operation we ultimately want to perform */
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unsigned char data_cmnd[MAX_COMMAND_SIZE];
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unsigned short old_use_sg; /* We save use_sg here when requesting
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* sense info */
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unsigned short use_sg; /* Number of pieces of scatter-gather */
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unsigned short sglist_len; /* size of malloc'd scatter-gather list */
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unsigned bufflen; /* Size of data buffer */
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void *buffer; /* Data buffer */
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unsigned underflow; /* Return error if less than
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this amount is transferred */
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unsigned old_underflow; /* save underflow here when reusing the
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* command for error handling */
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unsigned transfersize; /* How much we are guaranteed to
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transfer with each SCSI transfer
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(ie, between disconnect /
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reconnects. Probably == sector
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size */
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int resid; /* Number of bytes requested to be
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transferred less actual number
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transferred (0 if not supported) */
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struct request *request; /* The command we are
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working on */
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#define SCSI_SENSE_BUFFERSIZE 96
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unsigned char sense_buffer[SCSI_SENSE_BUFFERSIZE];
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/* obtained by REQUEST SENSE when
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* CHECK CONDITION is received on original
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* command (auto-sense) */
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/* Low-level done function - can be used by low-level driver to point
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* to completion function. Not used by mid/upper level code. */
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void (*scsi_done) (struct scsi_cmnd *);
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/*
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* The following fields can be written to by the host specific code.
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* Everything else should be left alone.
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*/
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struct scsi_pointer SCp; /* Scratchpad used by some host adapters */
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unsigned char *host_scribble; /* The host adapter is allowed to
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* call scsi_malloc and get some memory
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* and hang it here. The host adapter
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* is also expected to call scsi_free
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* to release this memory. (The memory
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* obtained by scsi_malloc is guaranteed
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* to be at an address < 16Mb). */
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int result; /* Status code from lower level driver */
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unsigned char tag; /* SCSI-II queued command tag */
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unsigned long pid; /* Process ID, starts at 0. Unique per host. */
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};
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/*
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* These are the values that scsi_cmd->state can take.
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*/
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#define SCSI_STATE_TIMEOUT 0x1000
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#define SCSI_STATE_FINISHED 0x1001
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#define SCSI_STATE_FAILED 0x1002
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#define SCSI_STATE_QUEUED 0x1003
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#define SCSI_STATE_UNUSED 0x1006
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#define SCSI_STATE_DISCONNECTING 0x1008
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#define SCSI_STATE_INITIALIZING 0x1009
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#define SCSI_STATE_BHQUEUE 0x100a
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#define SCSI_STATE_MLQUEUE 0x100b
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extern struct scsi_cmnd *scsi_get_command(struct scsi_device *, gfp_t);
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extern void scsi_put_command(struct scsi_cmnd *);
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extern void scsi_io_completion(struct scsi_cmnd *, unsigned int, unsigned int);
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extern void scsi_finish_command(struct scsi_cmnd *cmd);
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extern void *scsi_kmap_atomic_sg(struct scatterlist *sg, int sg_count,
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size_t *offset, size_t *len);
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extern void scsi_kunmap_atomic_sg(void *virt);
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#endif /* _SCSI_SCSI_CMND_H */
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