There is an error with the medium access timeout feature of the sd driver. The
sdkp->medium_access_timed_out value is set to zero in sd_done() in the wrong
place. It is set to zero only if a command returns sense data. If an I/O
command times out, error handling succeeds, and the I/O command completes, the
value won't be reset if nothing generates a sense response. Then, another
timeout (no matter how far in the future) can increment it again, causing the
device to be prematurely set offline.
The resetting of sdkp->medium_access_timed_out should occur before the check for
sense data.
Signed-off-by: David Jeffery <djeffery@xxxxxxxxxx>
---
To reproduce using scsi_debug, use SCSI_DEBUG_OPT_TIMEOUT or
SCSI_DEBUG_OPT_MAC_TIMEOUT to force an I/O command to timeout. Then, remove
the opt value so the I/O will succeed on retry. Perform more I/O as desired.
Finally, repeat the process to make a new I/O command time out. Without the
patch, the device will be marked offline even though many I/O commands have
succeeded between the 2 instances of timed out commands.
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 86fcf2c..2779e6b 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1669,12 +1669,12 @@ static int sd_done(struct scsi_cmnd *SCpnt)
sshdr.ascq));
}
#endif
+ sdkp->medium_access_timed_out = 0;
+
if (driver_byte(result) != DRIVER_SENSE &&
(!sense_valid || sense_deferred))
goto out;
- sdkp->medium_access_timed_out = 0;
-
switch (sshdr.sense_key) {
case HARDWARE_ERROR:
case MEDIUM_ERROR:
--
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