* [PATCH] scsi: Introduce sdev_printk_ratelimited to throttle frequent printk
@ 2018-03-28 8:43 Wen Yang
2018-03-29 23:56 ` Bart Van Assche
0 siblings, 1 reply; 2+ messages in thread
From: Wen Yang @ 2018-03-28 8:43 UTC (permalink / raw)
To: jejb, martin.petersen
Cc: linux-scsi, linux-kernel, Bart.VanAssche, pmladek,
sergey.senozhatsky.work, tj, jiang.biao2, zhong.weidong,
wen.yang99, Tan Hu
There would be so many same lines printed by frequent prink if one
disk went wrong, like,
[ 546.185242] sd 0:1:0:0: rejecting I/O to offline device
[ 546.185258] sd 0:1:0:0: rejecting I/O to offline device
[ 546.185280] sd 0:1:0:0: rejecting I/O to offline device
[ 546.185307] sd 0:1:0:0: rejecting I/O to offline device
[ 546.185334] sd 0:1:0:0: rejecting I/O to offline device
[ 546.185364] sd 0:1:0:0: rejecting I/O to offline device
[ 546.185390] sd 0:1:0:0: rejecting I/O to offline device
[ 546.185410] sd 0:1:0:0: rejecting I/O to offline device
For slow serial console, the frequent prink may block the printk, and
if spin_lock was acquired before the printk like in scsi_request_fn,
that could trigger the watchdog.
Relative disscussion can be found here,
https://bugzilla.kernel.org/show_bug.cgi?id=199003
And Petr brought the idea to throttle the frequent printk here, it's
useless to print the same lines frequently after all.
Suggested-by: Petr Mladek <pmladek@suse.com>
Suggested-by: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Signed-off-by: Jiang Biao <jiang.biao2@zte.com.cn>
Signed-off-by: Tan Hu <tan.hu@zte.com.cn>
CC: BartVanAssche <Bart.VanAssche@wdc.com>
CC: Petr Mladek <pmladek@suse.com>
CC: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
CC: Martin K. Petersen <martin.petersen@oracle.com>
CC: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
CC: Tejun Heo <tj@kernel.org>
---
drivers/scsi/scsi_lib.c | 6 +++---
include/scsi/scsi_device.h | 10 ++++++++++
2 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index c84f931..f77e801 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1301,7 +1301,7 @@ static int scsi_setup_cmnd(struct scsi_device *sdev, struct request *req)
* commands. The device must be brought online
* before trying any recovery commands.
*/
- sdev_printk(KERN_ERR, sdev,
+ sdev_printk_ratelimited(KERN_ERR, sdev,
"rejecting I/O to offline device\n");
ret = BLKPREP_KILL;
break;
@@ -1310,7 +1310,7 @@ static int scsi_setup_cmnd(struct scsi_device *sdev, struct request *req)
* If the device is fully deleted, we refuse to
* process any commands as well.
*/
- sdev_printk(KERN_ERR, sdev,
+ sdev_printk_ratelimited(KERN_ERR, sdev,
"rejecting I/O to dead device\n");
ret = BLKPREP_KILL;
break;
@@ -1802,7 +1802,7 @@ static void scsi_request_fn(struct request_queue *q)
break;
if (unlikely(!scsi_device_online(sdev))) {
- sdev_printk(KERN_ERR, sdev,
+ sdev_printk_ratelimited(KERN_ERR, sdev,
"rejecting I/O to offline device\n");
scsi_kill_request(req, q);
continue;
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 7ae177c..378d3f2 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -249,6 +249,16 @@ struct scsi_device {
#define sdev_printk(l, sdev, fmt, a...) \
sdev_prefix_printk(l, sdev, NULL, fmt, ##a)
+#define sdev_printk_ratelimited(l, sdev, fmt, a...) \
+({ \
+ static DEFINE_RATELIMIT_STATE(_rs, \
+ DEFAULT_RATELIMIT_INTERVAL, \
+ DEFAULT_RATELIMIT_BURST); \
+ \
+ if (__ratelimit(&_rs)) \
+ sdev_prefix_printk(l, sdev, NULL, fmt, ##a); \
+})
+
__printf(3, 4) void
scmd_printk(const char *, const struct scsi_cmnd *, const char *, ...);
--
1.8.3.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] scsi: Introduce sdev_printk_ratelimited to throttle frequent printk
2018-03-28 8:43 [PATCH] scsi: Introduce sdev_printk_ratelimited to throttle frequent printk Wen Yang
@ 2018-03-29 23:56 ` Bart Van Assche
0 siblings, 0 replies; 2+ messages in thread
From: Bart Van Assche @ 2018-03-29 23:56 UTC (permalink / raw)
To: jejb, wen.yang99, martin.petersen
Cc: linux-kernel, jiang.biao2, zhong.weidong,
sergey.senozhatsky.work, pmladek, linux-scsi, tan.hu, tj
On Wed, 2018-03-28 at 16:43 +0800, Wen Yang wrote:
> There would be so many same lines printed by frequent prink if one
> disk went wrong, like,
> [ 546.185242] sd 0:1:0:0: rejecting I/O to offline device
> [ 546.185258] sd 0:1:0:0: rejecting I/O to offline device
> [ 546.185280] sd 0:1:0:0: rejecting I/O to offline device
> [ 546.185307] sd 0:1:0:0: rejecting I/O to offline device
> [ 546.185334] sd 0:1:0:0: rejecting I/O to offline device
> [ 546.185364] sd 0:1:0:0: rejecting I/O to offline device
> [ 546.185390] sd 0:1:0:0: rejecting I/O to offline device
> [ 546.185410] sd 0:1:0:0: rejecting I/O to offline device
> For slow serial console, the frequent prink may block the printk, and
> if spin_lock was acquired before the printk like in scsi_request_fn,
> that could trigger the watchdog.
>
> Relative disscussion can be found here,
^^^^^^^^
Related?
Anyway:
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
^ permalink raw reply [flat|nested] 2+ messages in thread
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