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| 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 /include/scsi/scsi_device.h | |
| parent | 71e75c97f97a9645d25fbf3d8e4165a558f18747 (diff) | |
| download | blackbird-op-linux-cd9070c9c512ff7995f9019392e0ae548df3a088.tar.gz blackbird-op-linux-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 'include/scsi/scsi_device.h')
| -rw-r--r-- | include/scsi/scsi_device.h | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 3329901c7243..0f853f2c9dc7 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -82,6 +82,8 @@ struct scsi_device { struct list_head same_target_siblings; /* just the devices sharing same target id */ atomic_t device_busy; /* commands actually active on LLDD */ + atomic_t device_blocked; /* Device returned QUEUE_FULL. */ + spinlock_t list_lock; struct list_head cmd_list; /* queue of in use SCSI Command structures */ struct list_head starved_entry; @@ -180,8 +182,6 @@ struct scsi_device { struct list_head event_list; /* asserted events */ struct work_struct event_work; - unsigned int device_blocked; /* Device returned QUEUE_FULL. */ - unsigned int max_device_blocked; /* what device_blocked counts down from */ #define SCSI_DEFAULT_DEVICE_BLOCKED 3 @@ -291,12 +291,13 @@ struct scsi_target { * the same target will also. */ /* commands actually active on LLD. */ atomic_t target_busy; + atomic_t target_blocked; + /* * LLDs should set this in the slave_alloc host template callout. * If set to zero then there is not limit. */ unsigned int can_queue; - unsigned int target_blocked; unsigned int max_target_blocked; #define SCSI_DEFAULT_TARGET_BLOCKED 3 |
