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 <[email protected]> Suggested-by: Sergey Senozhatsky <[email protected]> Signed-off-by: Wen Yang <[email protected]> Signed-off-by: Jiang Biao <[email protected]> Signed-off-by: Tan Hu <[email protected]> CC: BartVanAssche <[email protected]> CC: Petr Mladek <[email protected]> CC: Sergey Senozhatsky <[email protected]> CC: Martin K. Petersen <[email protected]> CC: "James E.J. Bottomley" <[email protected]> CC: Tejun Heo <[email protected]> --- 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
