This patch adds rate limits to SCSI sense code uevets. Currently,
the rate limit is hard-coded to 16 events per second.
The code tracks nano second time of latest 16 events in a circular
buffer. When a new event arrives, the time is compared against the
latest time in the buffer. If the difference is smaller than one
second, the new event is dropped.
Signed-off-by: Song Liu <songliubraving@xxxxxx>
---
drivers/scsi/scsi_error.c | 15 +++++++++++++++
drivers/scsi/scsi_scan.c | 4 ++++
include/scsi/scsi_device.h | 12 +++++++++++-
3 files changed, 30 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index a49c63a..91e6b0a 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -436,11 +436,26 @@ static void scsi_send_sense_uevent(struct scsi_device *sdev,
#ifdef CONFIG_SCSI_SENSE_UEVENT
struct scsi_event *evt;
unsigned char sb_len;
+ unsigned long flags;
+ u64 time_ns;
if (!test_bit(sshdr->sense_key & 0xf,
&sdev->sense_event_filter))
return;
evt = sdev_evt_alloc(SDEV_EVT_SCSI_SENSE, GFP_ATOMIC);
+
+ time_ns = ktime_to_ns(ktime_get());
+ spin_lock_irqsave(&sdev->latest_event_lock, flags);
+ if (time_ns - sdev->latest_event_times[sdev->latest_event_idx] <
+ NSEC_PER_SEC) {
+ spin_unlock_irqrestore(&sdev->latest_event_lock, flags);
+ return;
+ }
+ sdev->latest_event_times[sdev->latest_event_idx] = time_ns;
+ sdev->latest_event_idx = (sdev->latest_event_idx + 1) %
+ MAX_SENSE_EVENT_PER_SECOND;
+ spin_unlock_irqrestore(&sdev->latest_event_lock, flags);
+
if (!evt)
return;
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 6f7128f..67b3f71 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -301,6 +301,10 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
}
}
+#ifdef CONFIG_SCSI_SENSE_UEVENT
+ spin_lock_init(&sdev->latest_event_lock);
+#endif
+
return sdev;
out_device_destroy:
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 5b6f06d..9217dae 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -214,12 +214,22 @@ struct scsi_device {
atomic_t ioerr_cnt;
#ifdef CONFIG_SCSI_SENSE_UEVENT
+#define MAX_SENSE_EVENT_PER_SECOND 16
/*
* filter of sense code uevent
* setting bit X (0x00 - 0x0e) of sense_event_filter enables
* uevent for sense key X
*/
- unsigned long sense_event_filter;
+ unsigned long sense_event_filter;
+ /*
+ * To rate limit uevents to MAX_SENSE_EVENT_PER_SECOND, we track
+ * nano second time of MAX_SENSE_EVENT_PER_SECOND most recent
+ * events. If there are already MAX_SENSE_EVENT_PER_SECOND in the
+ * past seconds, new event is dropped.
+ */
+ u64 latest_event_times[MAX_SENSE_EVENT_PER_SECOND];
+ int latest_event_idx;
+ spinlock_t latest_event_lock;
#endif
struct device sdev_gendev,
--
2.9.3
