> The above call would free the cmnd->cmnd and set it to null. If then
> scsi_io_completion was going to do some error processing it looks like
> it could try to access the scsi_cmnd->cmnd field.
>
> With the current code that would not be a problem because the blk unprep
> callback is not called until the block layer does its request cleanup in
> blk_finish_request which as you know is after
> scsi_io_completion/scsi_end_request is done with the cmnd.
This incremental patches fixes the issue, and makes sure the uninit calls are
nicely paired like the rest of the I/O completion routines after patch 2:
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 48c5c77..8e79612 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -490,8 +490,6 @@ static void scsi_requeue_command(struct request_queue *q,
struct scsi_cmnd *cmd)
struct request *req = cmd->request;
unsigned long flags;
- scsi_uninit_command(cmd);
-
spin_lock_irqsave(q->queue_lock, flags);
blk_unprep_request(req);
req->special = NULL;
@@ -941,6 +939,7 @@ requeue:
/* Unprep the request and put it back at the head of the queue.
* A new command will be prepared and issued.
*/
+ scsi_uninit_command(cmd);
scsi_release_buffers(cmd);
scsi_requeue_command(q, cmd);
break;
@@ -956,6 +955,7 @@ requeue:
return;
next_command:
+ scsi_uninit_command(cmd);
scsi_release_buffers(cmd);
scsi_next_command(cmd);
}
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index d95c4fd..d99cb3f 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1652,8 +1652,6 @@ static int sd_done(struct scsi_cmnd *SCpnt)
unsigned char op = SCpnt->cmnd[0];
unsigned char unmap = SCpnt->cmnd[1] & 8;
- sd_uninit_command(SCpnt);
-
if (req->cmd_flags & REQ_DISCARD || req->cmd_flags & REQ_WRITE_SAME) {
if (!result) {
good_bytes = blk_rq_bytes(req);
--
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