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_sysfs.c | |
| parent | 71e75c97f97a9645d25fbf3d8e4165a558f18747 (diff) | |
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_sysfs.c')
| -rw-r--r-- | drivers/scsi/scsi_sysfs.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index 79df9847edef..209cae3097ea 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -584,7 +584,6 @@ static int scsi_sdev_check_buf_bit(const char *buf) /* * Create the actual show/store functions and data structures. */ -sdev_rd_attr (device_blocked, "%d\n"); sdev_rd_attr (type, "%d\n"); sdev_rd_attr (scsi_level, "%d\n"); sdev_rd_attr (vendor, "%.8s\n"); @@ -600,6 +599,15 @@ sdev_show_device_busy(struct device *dev, struct device_attribute *attr, } static DEVICE_ATTR(device_busy, S_IRUGO, sdev_show_device_busy, NULL); +static ssize_t +sdev_show_device_blocked(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct scsi_device *sdev = to_scsi_device(dev); + return snprintf(buf, 20, "%d\n", atomic_read(&sdev->device_blocked)); +} +static DEVICE_ATTR(device_blocked, S_IRUGO, sdev_show_device_blocked, NULL); + /* * TODO: can we make these symlinks to the block layer ones? */ |