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>
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index e4a5324..5db8454 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -59,7 +59,7 @@
/* called with shost->host_lock held */
void scsi_eh_wakeup(struct Scsi_Host *shost)
{
- if (shost->host_busy == shost->host_failed) {
+ if (atomic_read(&shost->host_busy) == shost->host_failed) {
trace_scsi_eh_wakeup(shost);
wake_up_process(shost->ehandler);
SCSI_LOG_ERROR_RECOVERY(5, shost_printk(KERN_INFO, shost,
@@ -2164,7 +2164,7 @@
while (!kthread_should_stop()) {
set_current_state(TASK_INTERRUPTIBLE);
if ((shost->host_failed == 0 && shost->host_eh_scheduled == 0) ||
- shost->host_failed != shost->host_busy) {
+ shost->host_failed != atomic_read(&shost->host_busy)) {
SCSI_LOG_ERROR_RECOVERY(1,
shost_printk(KERN_INFO, shost,
"scsi_eh_%d: sleeping\n",
@@ -2178,7 +2178,8 @@
shost_printk(KERN_INFO, shost,
"scsi_eh_%d: waking up %d/%d/%d\n",
shost->host_no, shost->host_eh_scheduled,
- shost->host_failed, shost->host_busy));
+ shost->host_failed,
+ atomic_read(&shost->host_busy)));
/*
* We have a host that is failing for some reason. Figure out