Commit 79ed2429 authored by James Bottomley's avatar James Bottomley
Browse files

[SCSI] scsi_lib: fix DID_RESET status problems 



Andrew Vaszquez said:
> There's a problem that is causing commands returned by the LLD with
> a DID_RESET status to be reissued with cleared cmd->sdb data which
> in our tests are manifesting in firmware detected overruns.  Here's
> a snippet of a READ_10 scsi_cmnd upon completion by the storage

The problem is caused by:

commit b60af5b0
Author: Alan Stern <stern@rowland.harvard.edu>
Date:   Mon Nov 3 15:56:47 2008 -0500

    [SCSI] simplify scsi_io_completion()

Because scsi_release_buffers() is called before commands that go
through the ACTION_RETRY and ACTION_DELAYED_RETRY legs are requeued.
However, they're not re-prepared, so nothing ever reallocates the
buffer resources to them.  Fix this by releasing the buffers only if
we're not going to go down these legs (but scsi_release_buffers() on
all legs including two in scsi_end_request(); this latter needs a
special version __scsi_release_buffers() because the final one can be
called after the request has been freed, so the bidi test in
scsi_release_buffers(), which touches the request has to be skipped).

Reported-by: default avatarAndrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
parent 4be98c0c

drivers/scsi/scsi_lib.c

+27 −16
Original line number Diff line number Diff line
@@ -701,6 +701,8 @@ void scsi_run_host_queues(struct Scsi_Host *shost) 
		scsi_run_queue(sdev->request_queue);

}



static void __scsi_release_buffers(struct scsi_cmnd *, int);



/*

 * Function:    scsi_end_request()

 *
@@ -749,6 +751,7 @@ static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error, 
				 * leftovers in the front of the

				 * queue, and goose the queue again.

				 */

				scsi_release_buffers(cmd);

				scsi_requeue_command(q, cmd);

				cmd = NULL;

			}
@@ -760,6 +763,7 @@ static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error, 
	 * This will goose the queue request function at the end, so we don't

	 * need to worry about launching another command.

	 */

	__scsi_release_buffers(cmd, 0);

	scsi_next_command(cmd);

	return NULL;

}
@@ -815,6 +819,26 @@ static void scsi_free_sgtable(struct scsi_data_buffer *sdb) 
	__sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);

}



static void __scsi_release_buffers(struct scsi_cmnd *cmd, int do_bidi_check)

{



	if (cmd->sdb.table.nents)

		scsi_free_sgtable(&cmd->sdb);



	memset(&cmd->sdb, 0, sizeof(cmd->sdb));



	if (do_bidi_check && scsi_bidi_cmnd(cmd)) {

		struct scsi_data_buffer *bidi_sdb =

			cmd->request->next_rq->special;

		scsi_free_sgtable(bidi_sdb);

		kmem_cache_free(scsi_sdb_cache, bidi_sdb);

		cmd->request->next_rq->special = NULL;

	}



	if (scsi_prot_sg_count(cmd))

		scsi_free_sgtable(cmd->prot_sdb);

}



/*

 * Function:    scsi_release_buffers()

 *
@@ -834,21 +858,7 @@ static void scsi_free_sgtable(struct scsi_data_buffer *sdb) 
 */

void scsi_release_buffers(struct scsi_cmnd *cmd)

{

	if (cmd->sdb.table.nents)

		scsi_free_sgtable(&cmd->sdb);



	memset(&cmd->sdb, 0, sizeof(cmd->sdb));



	if (scsi_bidi_cmnd(cmd)) {

		struct scsi_data_buffer *bidi_sdb =

			cmd->request->next_rq->special;

		scsi_free_sgtable(bidi_sdb);

		kmem_cache_free(scsi_sdb_cache, bidi_sdb);

		cmd->request->next_rq->special = NULL;

	}



	if (scsi_prot_sg_count(cmd))

		scsi_free_sgtable(cmd->prot_sdb);

	__scsi_release_buffers(cmd, 1);

}

EXPORT_SYMBOL(scsi_release_buffers);
@@ -962,7 +972,6 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) 
	}



	BUG_ON(blk_bidi_rq(req)); /* bidi not support for !blk_pc_request yet */

	scsi_release_buffers(cmd);



	/*

	 * Next deal with any sectors which we were able to correctly
@@ -1080,6 +1089,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) 
	switch (action) {

	case ACTION_FAIL:

		/* Give up and fail the remainder of the request */

		scsi_release_buffers(cmd);

		if (!(req->cmd_flags & REQ_QUIET)) {

			if (description)

				scmd_printk(KERN_INFO, cmd, "%s\n",
@@ -1095,6 +1105,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) 
		/* Unprep the request and put it back at the head of the queue.

		 * A new command will be prepared and issued.

		 */

		scsi_release_buffers(cmd);

		scsi_requeue_command(q, cmd);

		break;

	case ACTION_RETRY:

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