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[block] Retry any SAN device operation 

The SCSI layer currently implements a retry loop in order to retry
commands that fail due to spurious "error" conditions such as "power
on occurred".  Move this retry loop to the generic SAN device layer:
this allow for retries due to other transient error conditions such as
an iSCSI target having dropped the connection due to inactivity.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown 2017-03-07 16:11:22 +00:00
parent 23d388418e
commit d9886f1961
2 changed files with 39 additions and 46 deletions
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60
src/core/sanboot.c
View File

@ -64,6 +64,16 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
*/
#define SAN_COMMAND_TIMEOUT ( 15 * TICKS_PER_SEC )
/**
* Number of times to retry commands
*
* We may need to retry commands. For example, the underlying
* connection may be closed by the SAN target due to an inactivity
* timeout, or the SAN target may return pointless "error" messages
* such as "SCSI power-on occurred".
*/
#define SAN_COMMAND_MAX_RETRIES 10
/** List of SAN devices */
LIST_HEAD ( san_devices );
@ -331,36 +341,42 @@ sandev_command ( struct san_device *sandev,
int ( * command ) ( struct san_device *sandev,
const union san_command_params *params ),
const union san_command_params *params ) {
unsigned int retries;
int rc;
/* Sanity check */
assert ( ! timer_running ( &sandev->timer ) );
/* Reopen block device if applicable */
if ( sandev_needs_reopen ( sandev ) &&
( ( rc = sandev_reopen ( sandev ) ) != 0 ) ) {
goto err_reopen;
/* (Re)try command */
for ( retries = 0 ; retries < SAN_COMMAND_MAX_RETRIES ; retries++ ) {
/* Reopen block device if applicable */
if ( sandev_needs_reopen ( sandev ) &&
( ( rc = sandev_reopen ( sandev ) ) != 0 ) ) {
continue;
}
/* Start expiry timer */
start_timer_fixed ( &sandev->timer, SAN_COMMAND_TIMEOUT );
/* Initiate command */
if ( ( rc = command ( sandev, params ) ) != 0 ) {
stop_timer ( &sandev->timer );
continue;
}
/* Wait for command to complete */
while ( timer_running ( &sandev->timer ) )
step();
/* Exit on success */
if ( ( rc = sandev->command_rc ) == 0 )
return 0;
}
/* Start expiry timer */
start_timer_fixed ( &sandev->timer, SAN_COMMAND_TIMEOUT );
/* Sanity check */
assert ( ! timer_running ( &sandev->timer ) );
/* Initiate command */
if ( ( rc = command ( sandev, params ) ) != 0 )
goto err_op;
/* Wait for command to complete */
while ( timer_running ( &sandev->timer ) )
step();
/* Collect return status */
rc = sandev->command_rc;
return rc;
err_op:
stop_timer ( &sandev->timer );
err_reopen:
return rc;
}

25
src/drivers/block/scsi.c
View File

@ -40,9 +40,6 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
*
*/
/** Maximum number of command retries */
#define SCSICMD_MAX_RETRIES 10
/* Error numbers generated by SCSI sense data */
#define EIO_NO_SENSE __einfo_error ( EINFO_EIO_NO_SENSE )
#define EINFO_EIO_NO_SENSE \
@ -283,9 +280,6 @@ struct scsi_command {
/** Command tag */
uint32_t tag;
/** Retry count */
unsigned int retries;
/** Private data */
uint8_t priv[0];
};
@ -449,28 +443,11 @@ static int scsicmd_command ( struct scsi_command *scsicmd ) {
* @v rc Reason for close
*/
static void scsicmd_done ( struct scsi_command *scsicmd, int rc ) {
struct scsi_device *scsidev = scsicmd->scsidev;
/* Restart SCSI interface */
intf_restart ( &scsicmd->scsi, rc );
/* SCSI targets have an annoying habit of returning occasional
* pointless "error" messages such as "power-on occurred", so
* we have to be prepared to retry commands.
*/
if ( ( rc != 0 ) && ( scsicmd->retries++ < SCSICMD_MAX_RETRIES ) ) {
/* Retry command */
DBGC ( scsidev, "SCSI %p tag %08x failed: %s\n",
scsidev, scsicmd->tag, strerror ( rc ) );
DBGC ( scsidev, "SCSI %p tag %08x retrying (retry %d)\n",
scsidev, scsicmd->tag, scsicmd->retries );
if ( ( rc = scsicmd_command ( scsicmd ) ) == 0 )
return;
}
/* If we didn't (successfully) reissue the command, hand over
* to the command completion handler.
*/
/* Hand over to the command completion handler */
scsicmd->type->done ( scsicmd, rc );
}