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esp_scsi: Fix tag state corruption when autosensing.

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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: Meelis Roos <mroos@linux.ee>
Tested-by: Meelis Roos <mroos@linux.ee>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2013-08-01 18:08:34 -07:00
parent ab2abda637
commit 21af8107f2
2 changed files with 9 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

14
drivers/scsi/esp_scsi.c
View file

@ -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;

1
drivers/scsi/esp_scsi.h
View file

@ -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;