Re: [PATCH scsi-misc-2.6 07/13] scsi: move error handling out of scsi_init_io() into scsi_prep_fn()

[Tejun Heo <htejun@gmail.com>]

07_scsi_consolidate_prep_fn_error_handling.patch

	When scsi_init_io() returns BLKPREP_DEFER or BLKPREP_KILL,
	it's supposed to free resources itself.  This patch
	consolidates defer and kill handling into scsi_prep_fn().
	This fixes a queue stall bug which occurred when sgtable
	allocation failed and device_busy == 0.

Signed-off-by: Tejun Heo <htejun@gmail.com>

 scsi_lib.c |   23 ++++++++++++-----------
 1 files changed, 12 insertions(+), 11 deletions(-)

Index: scsi-export/drivers/scsi/scsi_lib.c
===================================================================
--- scsi-export.orig/drivers/scsi/scsi_lib.c	2005-03-31 18:06:21.000000000 +0900
+++ scsi-export/drivers/scsi/scsi_lib.c	2005-03-31 18:06:21.000000000 +0900
@@ -960,9 +960,6 @@ static int scsi_init_io(struct scsi_cmnd
 	printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors,
 			req->current_nr_sectors);
 
-	/* release the command and kill it */
-	scsi_release_buffers(cmd);
-	scsi_put_command(cmd);
 	return BLKPREP_KILL;
 }
 
@@ -1130,18 +1127,17 @@ static int scsi_prep_fn(struct request_q
 		 * required).
 		 */
 		ret = scsi_init_io(cmd);
-		if (ret)	/* BLKPREP_KILL return also releases the command */
-			return ret;
-		
+		if (ret == BLKPREP_DEFER)
+			goto defer;
+		else if (ret == BLKPREP_KILL)
+			goto kill;
+
 		/*
 		 * Initialize the actual SCSI command for this request.
 		 */
 		drv = *(struct scsi_driver **)req->rq_disk->private_data;
-		if (unlikely(!drv->init_command(cmd))) {
-			scsi_release_buffers(cmd);
-			scsi_put_command(cmd);
-			return BLKPREP_KILL;
-		}
+		if (unlikely(!drv->init_command(cmd)))
+			goto kill;
 	}
 
 	/*
@@ -1157,6 +1153,11 @@ static int scsi_prep_fn(struct request_q
 	if (sdev->device_busy == 0)
 		blk_plug_device(q);
 	return BLKPREP_DEFER;
+
+ kill:
+	scsi_release_buffers(cmd);
+	scsi_put_command(cmd);
+	return BLKPREP_KILL;
 }
 
 /*