The patch titled
scsi: use lock per host instead of per device for shared queue tag host
has been added to the -mm tree. Its filename is
scsi-use-lock-per-host-instead-of-per-device-for-shared-queue-tag-host.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: scsi: use lock per host instead of per device for shared queue tag host
From: "Ed Lin" <ed.lin@xxxxxxxxxxx>
The block layer uses lock to protect request queue. Every scsi device has
a unique request queue, and queue lock is the default lock in struct
request_queue. This is good for normal cases. But for a host with shared
queue tag (e.g. stex controllers), a queue lock per device means the
shared queue tag is not protected when multiple devices are accessed at a
same time. This patch is a simple fix for this situation by introducing a
host queue lock to protect shared queue tag. Without this patch we will
see various kernel panics (including the BUG() and kernel errors in
blk_queue_start_tag and blk_queue_end_tag of ll_rw_blk.c) when accessing
another in smp kernels).
Signed-off-by: Ed Lin <ed.lin@xxxxxxxxxxx>
Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxx>
Cc: Jeff Garzik <jeff@xxxxxxxxxx>
Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/scsi/scsi_lib.c | 2 +-
drivers/scsi/stex.c | 2 ++
include/scsi/scsi_host.h | 3 +++
3 files changed, 6 insertions(+), 1 deletion(-)
diff -puN drivers/scsi/scsi_lib.c~scsi-use-lock-per-host-instead-of-per-device-for-shared-queue-tag-host drivers/scsi/scsi_lib.c
--- a/drivers/scsi/scsi_lib.c~scsi-use-lock-per-host-instead-of-per-device-for-shared-queue-tag-host
+++ a/drivers/scsi/scsi_lib.c
@@ -1670,7 +1670,7 @@ struct request_queue *__scsi_alloc_queue
{
struct request_queue *q;
- q = blk_init_queue(request_fn, NULL);
+ q = blk_init_queue(request_fn, shost->req_q_lock);
if (!q)
return NULL;
diff -puN drivers/scsi/stex.c~scsi-use-lock-per-host-instead-of-per-device-for-shared-queue-tag-host drivers/scsi/stex.c
--- a/drivers/scsi/stex.c~scsi-use-lock-per-host-instead-of-per-device-for-shared-queue-tag-host
+++ a/drivers/scsi/stex.c
@@ -1234,6 +1234,8 @@ stex_probe(struct pci_dev *pdev, const s
if (err)
goto out_free_irq;
+ spin_lock_init(&host->__req_q_lock);
+ host->req_q_lock = &host->__req_q_lock;
err = scsi_init_shared_tag_map(host, host->can_queue);
if (err) {
printk(KERN_ERR DRV_NAME "(%s): init shared queue failed\n",
diff -puN include/scsi/scsi_host.h~scsi-use-lock-per-host-instead-of-per-device-for-shared-queue-tag-host include/scsi/scsi_host.h
--- a/include/scsi/scsi_host.h~scsi-use-lock-per-host-instead-of-per-device-for-shared-queue-tag-host
+++ a/include/scsi/scsi_host.h
@@ -503,6 +503,9 @@ struct Scsi_Host {
spinlock_t default_lock;
spinlock_t *host_lock;
+ spinlock_t __req_q_lock;
+ spinlock_t *req_q_lock;/* protect shared block queue tag */
+
struct mutex scan_mutex;/* serialize scanning activity */
struct list_head eh_cmd_q;
_
Patches currently in -mm which might be from ed.lin@xxxxxxxxxxx are
scsi-use-lock-per-host-instead-of-per-device-for-shared-queue-tag-host.patch
-
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