[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>

diff --git a/src/core/sanboot.c b/src/core/sanboot.c
index 42a30839251a2d28e205ffbbb6c51a7829119e47..85d0bc7f6aa3212de6bbd30d1fb89b3fbf958b18 100644 (file)
--- a/src/core/sanboot.c
+++ b/src/core/sanboot.c
@@ -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++ ) {
 
-       /* Start expiry timer */
-       start_timer_fixed ( &sandev->timer, SAN_COMMAND_TIMEOUT );
+               /* Reopen block device if applicable */
+               if ( sandev_needs_reopen ( sandev ) &&
+                    ( ( rc = sandev_reopen ( sandev ) ) != 0 ) ) {
+                       continue;
+               }
 
-       /* Initiate command */
-       if ( ( rc = command ( sandev, params ) ) != 0 )
-               goto err_op;
+               /* Start expiry timer */
+               start_timer_fixed ( &sandev->timer, SAN_COMMAND_TIMEOUT );
 
-       /* Wait for command to complete */
-       while ( timer_running ( &sandev->timer ) )
-               step();
+               /* Initiate command */
+               if ( ( rc = command ( sandev, params ) ) != 0 ) {
+                       stop_timer ( &sandev->timer );
+                       continue;
+               }
 
-       /* Collect return status */
-       rc = sandev->command_rc;
+               /* Wait for command to complete */
+               while ( timer_running ( &sandev->timer ) )
+                       step();
 
-       return rc;
+               /* Exit on success */
+               if ( ( rc = sandev->command_rc ) == 0 )
+                       return 0;
+       }
+
+       /* Sanity check */
+       assert ( ! timer_running ( &sandev->timer ) );
 
- err_op:
-       stop_timer ( &sandev->timer );
- err_reopen:
        return rc;
 }
 

diff --git a/src/drivers/block/scsi.c b/src/drivers/block/scsi.c
index fd5f82b9f539863340b29a96280cc97d01b03432..847e0d46cb80f29daa9073ac295ef6d196e36918 100644 (file)
--- a/src/drivers/block/scsi.c
+++ b/src/drivers/block/scsi.c
@@ -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 );
 }