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Commit 21af8107 authored by David S. Miller's avatar David S. Miller
Browse files

esp_scsi: Fix tag state corruption when autosensing. 



Meelis Roos reports a crash in esp_free_lun_tag() in the presense
of a disk which has died.

The issue is that when we issue an autosense command, we do so by
hijacking the original command that caused the check-condition.

When we do so we clear out the ent->tag[] array when we issue it via
find_and_prep_issuable_command().  This is so that the autosense
command is forced to be issued non-tagged.

That is problematic, because it is the value of ent->tag[] which
determines whether we issued the original scsi command as tagged
vs. non-tagged (see esp_alloc_lun_tag()).

And that, in turn, is what trips up the sanity checks in
esp_free_lun_tag().  That function needs the original ->tag[] values
in order to free up the tag slot properly.

Fix this by remembering the original command's tag values, and
having esp_alloc_lun_tag() and esp_free_lun_tag() use them.

Reported-by: default avatarMeelis Roos <mroos@linux.ee>
Tested-by: default avatarMeelis Roos <mroos@linux.ee>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ab2abda6

drivers/scsi/esp_scsi.c

+8 −6
Original line number Diff line number Diff line
@@ -530,7 +530,7 @@ static int esp_need_to_nego_sync(struct esp_target_data *tp) 
static int esp_alloc_lun_tag(struct esp_cmd_entry *ent,

			     struct esp_lun_data *lp)

{

	if (!ent->tag[0]) {

	if (!ent->orig_tag[0]) {

		/* Non-tagged, slot already taken?  */

		if (lp->non_tagged_cmd)

			return -EBUSY;
@@ -564,9 +564,9 @@ static int esp_alloc_lun_tag(struct esp_cmd_entry *ent, 
			return -EBUSY;

	}



	BUG_ON(lp->tagged_cmds[ent->tag[1]]);

	BUG_ON(lp->tagged_cmds[ent->orig_tag[1]]);



	lp->tagged_cmds[ent->tag[1]] = ent;

	lp->tagged_cmds[ent->orig_tag[1]] = ent;

	lp->num_tagged++;



	return 0;
@@ -575,9 +575,9 @@ static int esp_alloc_lun_tag(struct esp_cmd_entry *ent, 
static void esp_free_lun_tag(struct esp_cmd_entry *ent,

			     struct esp_lun_data *lp)

{

	if (ent->tag[0]) {

		BUG_ON(lp->tagged_cmds[ent->tag[1]] != ent);

		lp->tagged_cmds[ent->tag[1]] = NULL;

	if (ent->orig_tag[0]) {

		BUG_ON(lp->tagged_cmds[ent->orig_tag[1]] != ent);

		lp->tagged_cmds[ent->orig_tag[1]] = NULL;

		lp->num_tagged--;

	} else {

		BUG_ON(lp->non_tagged_cmd != ent);
@@ -667,6 +667,8 @@ static struct esp_cmd_entry *find_and_prep_issuable_command(struct esp *esp) 
			ent->tag[0] = 0;

			ent->tag[1] = 0;

		}

		ent->orig_tag[0] = ent->tag[0];

		ent->orig_tag[1] = ent->tag[1];



		if (esp_alloc_lun_tag(ent, lp) < 0)

			continue;

drivers/scsi/esp_scsi.h

+1 −0
Original line number Diff line number Diff line
@@ -271,6 +271,7 @@ struct esp_cmd_entry { 
#define ESP_CMD_FLAG_AUTOSENSE	0x04 /* Doing automatic REQUEST_SENSE */



	u8			tag[2];

	u8			orig_tag[2];



	u8			status;

	u8			message;