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[SCSI] scsi_error: Refactoring scsi_error to facilitate in synchronou…
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…s REQUEST_SENSE

 - Drivers/transports that want to send a synchronous REQUEST_SENSE command
   as part of their .queuecommand sequence, have 2 new API's that facilitate
   in doing so and abstract them from scsi-ml internals.

   void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd,
	struct scsi_eh_save *sesci, unsigned char *cmnd,
	int cmnd_size, int sense_bytes)

   Will hijack a command and prepare it for request sense if needed.
   And will save any later needed info into a scsi_eh_save structure.

   void scsi_eh_restore_cmnd(struct scsi_cmnd* scmd,
	struct scsi_eh_save *sesci);

   Will undo any changes done to a command by above function. Making
   it ready for completion.

 - Re-factor scsi_send_eh_cmnd() to use above APIs

Signed-off-by: Boaz Harrosh <[email protected]>
Signed-off-by: James Bottomley <[email protected]>
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Boaz Harrosh authored and James Bottomley committed Oct 12, 2007
1 parent 55db6c1 commit e1c2346
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Showing 2 changed files with 90 additions and 47 deletions.
114 changes: 68 additions & 46 deletions drivers/scsi/scsi_error.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -590,42 +590,23 @@ static void scsi_abort_eh_cmnd(struct scsi_cmnd *scmd)
}

/**
* scsi_send_eh_cmnd - submit a scsi command as part of error recory
* scsi_eh_prep_cmnd - Save a scsi command info as part of error recory
* @scmd: SCSI command structure to hijack
* @ses: structure to save restore information
* @cmnd: CDB to send. Can be NULL if no new cmnd is needed
* @cmnd_size: size in bytes of @cmnd
* @timeout: timeout for this request
* @sense_bytes: size of sense data to copy. or 0 (if != 0 @cmnd is ignored)
*
* This function is used to send a scsi command down to a target device
* This function is used to save a scsi command information before re-execution
* as part of the error recovery process. If @sense_bytes is 0 the command
* sent must be one that does not transfer any data. If @sense_bytes != 0
* @cmnd is ignored and this functions sets up a REQUEST_SENSE command
* and cmnd buffers to read @sense_bytes into @scmd->sense_buffer.
*
* Return value:
* SUCCESS or FAILED or NEEDS_RETRY
**/
static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
int cmnd_size, int timeout, unsigned sense_bytes)
void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses,
unsigned char *cmnd, int cmnd_size, unsigned sense_bytes)
{
struct scsi_device *sdev = scmd->device;
struct Scsi_Host *shost = sdev->host;
DECLARE_COMPLETION_ONSTACK(done);
unsigned long timeleft;
unsigned long flags;

unsigned char old_cmd_len;
unsigned char old_cmnd[MAX_COMMAND_SIZE];
enum dma_data_direction old_data_direction;
unsigned old_bufflen;
void *old_buffer;
unsigned short old_use_sg;
int old_resid;
int old_result;

struct scatterlist sgl;
int rtn;

/*
* We need saved copies of a number of fields - this is because
Expand All @@ -634,20 +615,21 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
* we will need to restore these values prior to running the actual
* command.
*/
old_cmd_len = scmd->cmd_len;
memcpy(old_cmnd, scmd->cmnd, sizeof(scmd->cmnd));
old_data_direction = scmd->sc_data_direction;
old_bufflen = scmd->request_bufflen;
old_buffer = scmd->request_buffer;
old_use_sg = scmd->use_sg;
old_resid = scmd->resid;
old_result = scmd->result;
ses->cmd_len = scmd->cmd_len;
memcpy(ses->cmnd, scmd->cmnd, sizeof(scmd->cmnd));
ses->data_direction = scmd->sc_data_direction;
ses->bufflen = scmd->request_bufflen;
ses->buffer = scmd->request_buffer;
ses->use_sg = scmd->use_sg;
ses->resid = scmd->resid;
ses->result = scmd->result;

if (sense_bytes) {
scmd->request_bufflen = min_t(unsigned,
sizeof(scmd->sense_buffer), sense_bytes);
sg_init_one(&sgl, scmd->sense_buffer, scmd->request_bufflen);
scmd->request_buffer = &sgl;
sg_init_one(&ses->sense_sgl, scmd->sense_buffer,
scmd->request_bufflen);
scmd->request_buffer = &ses->sense_sgl;
scmd->sc_data_direction = DMA_FROM_DEVICE;
scmd->use_sg = 1;
memset(scmd->cmnd, 0, sizeof(scmd->cmnd));
Expand Down Expand Up @@ -677,7 +659,58 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
* untransferred sense data should be interpreted as being zero.
*/
memset(scmd->sense_buffer, 0, sizeof(scmd->sense_buffer));
}
EXPORT_SYMBOL(scsi_eh_prep_cmnd);

/**
* scsi_eh_restore_cmnd - Restore a scsi command info as part of error recory
* @scmd: SCSI command structure to restore
* @ses: saved information from a coresponding call to scsi_prep_eh_cmnd
*
* Undo any damage done by above scsi_prep_eh_cmnd().
**/
void scsi_eh_restore_cmnd(struct scsi_cmnd* scmd, struct scsi_eh_save *ses)
{
/*
* Restore original data
*/
scmd->cmd_len = ses->cmd_len;
memcpy(scmd->cmnd, ses->cmnd, sizeof(scmd->cmnd));
scmd->sc_data_direction = ses->data_direction;
scmd->request_bufflen = ses->bufflen;
scmd->request_buffer = ses->buffer;
scmd->use_sg = ses->use_sg;
scmd->resid = ses->resid;
scmd->result = ses->result;
}
EXPORT_SYMBOL(scsi_eh_restore_cmnd);

/**
* scsi_send_eh_cmnd - submit a scsi command as part of error recory
* @scmd: SCSI command structure to hijack
* @cmnd: CDB to send
* @cmnd_size: size in bytes of @cmnd
* @timeout: timeout for this request
* @sense_bytes: size of sense data to copy or 0
*
* This function is used to send a scsi command down to a target device
* as part of the error recovery process. See also scsi_eh_prep_cmnd() above.
*
* Return value:
* SUCCESS or FAILED or NEEDS_RETRY
**/
static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
int cmnd_size, int timeout, unsigned sense_bytes)
{
struct scsi_device *sdev = scmd->device;
struct Scsi_Host *shost = sdev->host;
DECLARE_COMPLETION_ONSTACK(done);
unsigned long timeleft;
unsigned long flags;
struct scsi_eh_save ses;
int rtn;

scsi_eh_prep_cmnd(scmd, &ses, cmnd, cmnd_size, sense_bytes);
shost->eh_action = &done;

spin_lock_irqsave(shost->host_lock, flags);
Expand Down Expand Up @@ -721,18 +754,7 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
rtn = FAILED;
}


/*
* Restore original data
*/
scmd->cmd_len = old_cmd_len;
memcpy(scmd->cmnd, old_cmnd, sizeof(scmd->cmnd));
scmd->sc_data_direction = old_data_direction;
scmd->request_bufflen = old_bufflen;
scmd->request_buffer = old_buffer;
scmd->use_sg = old_use_sg;
scmd->resid = old_resid;
scmd->result = old_result;
scsi_eh_restore_cmnd(scmd, &ses);
return rtn;
}

Expand Down
23 changes: 22 additions & 1 deletion include/scsi/scsi_eh.h
View file
Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
#ifndef _SCSI_SCSI_EH_H
#define _SCSI_SCSI_EH_H

struct scsi_cmnd;
#include <scsi/scsi_cmnd.h>
struct scsi_device;
struct Scsi_Host;

Expand Down Expand Up @@ -65,4 +65,25 @@ extern int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,

extern int scsi_reset_provider(struct scsi_device *, int);

struct scsi_eh_save {
int result;
enum dma_data_direction data_direction;
unsigned char cmd_len;
unsigned char cmnd[MAX_COMMAND_SIZE];

void *buffer;
unsigned bufflen;
unsigned short use_sg;
int resid;

struct scatterlist sense_sgl;
};

extern void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd,
struct scsi_eh_save *ses, unsigned char *cmnd,
int cmnd_size, unsigned sense_bytes);

extern void scsi_eh_restore_cmnd(struct scsi_cmnd* scmd,
struct scsi_eh_save *ses);

#endif /* _SCSI_SCSI_EH_H */

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