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| author |   Christoph Hellwig <hch@lst.de> | 2014-01-22 15:29:29 +0100 |
|---|---|---|
| committer | Christoph Hellwig <hch@lst.de> | 2014-07-25 07:43:43 -0400 |
| commit | 74665016086615bbaa3fa6f83af410a0a4e029ee (patch) | |
| tree | 9f9d8a692bec91dce69fd303eeedf16c35b41ac6 /include/scsi | |
| parent | scsi: convert target_busy to an atomic_t (diff) | |
| download | linux-dev-74665016086615bbaa3fa6f83af410a0a4e029ee.tar.xz linux-dev-74665016086615bbaa3fa6f83af410a0a4e029ee.zip | |
scsi: convert host_busy to atomic_t
Avoid taking the host-wide host_lock to check the per-host queue limit.
Instead we do an atomic_inc_return early on to grab our slot in the queue,
and if necessary decrement it after finishing all checks.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
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 'include/scsi')
| -rw-r--r-- | include/scsi/scsi_host.h | 10 |
1 files changed, 3 insertions, 7 deletions
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h index b2bc5198b7fb..51f7911b1cbb 100644 --- a/include/scsi/scsi_host.h +++ b/include/scsi/scsi_host.h @@ -582,13 +582,9 @@ struct Scsi_Host { */ struct blk_queue_tag *bqt; - /* - * The following two fields are protected with host_lock; - * however, eh routines can safely access during eh processing - * without acquiring the lock. - */ - unsigned int host_busy; /* commands actually active on low-level */ - unsigned int host_failed; /* commands that failed. */ + atomic_t host_busy; /* commands actually active on low-level */ + unsigned int host_failed; /* commands that failed. + protected by host_lock */ unsigned int host_eh_scheduled; /* EH scheduled without command */ unsigned int host_no; /* Used for IOCTL_GET_IDLUN, /proc/scsi et al. */ |