diff options
| author |   Christoph Hellwig <hch@lst.de> | 2014-01-23 12:07:41 +0100 |
|---|---|---|
| committer | Christoph Hellwig <hch@lst.de> | 2014-07-25 17:15:48 -0400 |
| commit | cd9070c9c512ff7995f9019392e0ae548df3a088 (patch) | |
| tree | a426fccd5633f429f37dac237d8cf417ad9e7f31 /drivers/scsi/scsi.c | |
| parent | scsi: convert device_busy to atomic_t (diff) | |
| download | linux-dev-cd9070c9c512ff7995f9019392e0ae548df3a088.tar.xz linux-dev-cd9070c9c512ff7995f9019392e0ae548df3a088.zip | |
scsi: fix the {host,target,device}_blocked counter mess
Seems like these counters are missing any sort of synchronization for
updates, as a over 10 year old comment from me noted. Fix this by
using atomic counters, and while we're at it also make sure they are
in the same cacheline as the _busy counters and not needlessly stored
to in every I/O completion.
With the new model the _busy counters can temporarily go negative,
so all the readers are updated to check for > 0 values. Longer
term every successful I/O completion will reset the counters to zero,
so the temporarily negative values will not cause any harm.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Webb Scales <webbnh@hp.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Tested-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Robert Elliott <elliott@hp.com>
Diffstat (limited to 'drivers/scsi/scsi.c')
| -rw-r--r-- | drivers/scsi/scsi.c | 21 |
1 files changed, 10 insertions, 11 deletions
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c index 21fb97b01dd6..3dde8a35493f 100644 --- a/drivers/scsi/scsi.c +++ b/drivers/scsi/scsi.c @@ -726,17 +726,16 @@ void scsi_finish_command(struct scsi_cmnd *cmd) scsi_device_unbusy(sdev); - /* - * Clear the flags which say that the device/host is no longer - * capable of accepting new commands. These are set in scsi_queue.c - * for both the queue full condition on a device, and for a - * host full condition on the host. - * - * XXX(hch): What about locking? - */ - shost->host_blocked = 0; - starget->target_blocked = 0; - sdev->device_blocked = 0; + /* + * Clear the flags that say that the device/target/host is no longer + * capable of accepting new commands. + */ + if (atomic_read(&shost->host_blocked)) + atomic_set(&shost->host_blocked, 0); + if (atomic_read(&starget->target_blocked)) + atomic_set(&starget->target_blocked, 0); + if (atomic_read(&sdev->device_blocked)) + atomic_set(&sdev->device_blocked, 0); /* * If we have valid sense information, then some kind of recovery |