There would be so many same lines printed by frequent printk 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 printk may be blocked for a long time, and if any spin_lock has been acquired before the printk like in scsi_request_fn, watchdog could be triggered.
Related disscussion can be found here, https://bugzilla.kernel.org/show_bug.cgi?id=199003 And Petr brought the idea to throttle the frequent printk, it's useless to print the same lines frequently after all. v2: fix some typos v3: limit the print only for the same device Suggested-by: Petr Mladek <pmla...@suse.com> Suggested-by: Sergey Senozhatsky <sergey.senozhatsky.w...@gmail.com> Signed-off-by: Wen Yang <wen.yan...@zte.com.cn> Signed-off-by: Jiang Biao <jiang.bi...@zte.com.cn> Signed-off-by: Tan Hu <tan...@zte.com.cn> Reviewed-by: Bart Van Assche <bart.vanass...@wdc.com> CC: BartVanAssche <bart.vanass...@wdc.com> CC: Petr Mladek <pmla...@suse.com> CC: Sergey Senozhatsky <sergey.senozhatsky.w...@gmail.com> CC: Martin K. Petersen <martin.peter...@oracle.com> CC: "James E.J. Bottomley" <j...@linux.vnet.ibm.com> CC: Tejun Heo <t...@kernel.org> CC: JasonYan <yanai...@huawei.com> --- drivers/scsi/scsi_lib.c | 6 +++--- drivers/scsi/scsi_scan.c | 3 +++ include/scsi/scsi_device.h | 8 ++++++++ 3 files changed, 14 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/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c index 0880d97..a6da935 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -288,6 +288,9 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget, scsi_change_queue_depth(sdev, sdev->host->cmd_per_lun ? sdev->host->cmd_per_lun : 1); + /* Enable message ratelimiting. Default is 10 messages per 5 secs. */ + ratelimit_state_init(&sdev->sdev_ratelimit_state, + DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); scsi_sysfs_device_initialize(sdev); if (shost->hostt->slave_alloc) { diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 7ae177c..f1db7f3 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -215,6 +215,8 @@ struct scsi_device { struct device sdev_gendev, sdev_dev; + struct ratelimit_state sdev_ratelimit_state; /* Ratelimit sdev messages. */ + struct execute_work ew; /* used to get process context on put */ struct work_struct requeue_work; @@ -249,6 +251,12 @@ 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...) \ +({ \ + if (sdev && __ratelimit(&sdev->sdev_ratelimit_state)) \ + 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
