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[SCSI] ibmvfc: Fix dropped interrupts 

This patch fixes a problem of possible dropped interrupts. Currently,
the ibmvfc driver has a race condition where after ibmvfc_interrupt
gets run, the platform code clears the interrupt. This can result in
lost interrupts and, in worst case scenarios, result in command
timeouts. Fix this by implementing a tasklet similar to what the
ibmvscsi driver does so that interrupt processing is no longer done in
the actual interrupt handler, which eliminates the race.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
This commit is contained in:
Brian King 2009-03-20 15:44:35 -05:00 committed by James Bottomley
parent 8fe74cf053
commit 039a08981a
2 changed files with 24 additions and 2 deletions
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25
drivers/scsi/ibmvscsi/ibmvfc.c
View File

@ -640,6 +640,7 @@ static void ibmvfc_release_crq_queue(struct ibmvfc_host *vhost)
ibmvfc_dbg(vhost, "Releasing CRQ\n");
free_irq(vdev->irq, vhost);
tasklet_kill(&vhost->tasklet);
do {
rc = plpar_hcall_norets(H_FREE_CRQ, vdev->unit_address);
} while (rc == H_BUSY || H_IS_LONG_BUSY(rc));
@ -2699,6 +2700,25 @@ static struct ibmvfc_crq *ibmvfc_next_crq(struct ibmvfc_host *vhost)
static irqreturn_t ibmvfc_interrupt(int irq, void *dev_instance)
{
struct ibmvfc_host *vhost = (struct ibmvfc_host *)dev_instance;
unsigned long flags;
spin_lock_irqsave(vhost->host->host_lock, flags);
vio_disable_interrupts(to_vio_dev(vhost->dev));
tasklet_schedule(&vhost->tasklet);
spin_unlock_irqrestore(vhost->host->host_lock, flags);
return IRQ_HANDLED;
}
/**
* ibmvfc_tasklet - Interrupt handler tasklet
* @data: ibmvfc host struct
*
* Returns:
* Nothing
**/
static void ibmvfc_tasklet(void *data)
{
struct ibmvfc_host *vhost = data;
struct vio_dev *vdev = to_vio_dev(vhost->dev);
struct ibmvfc_crq *crq;
struct ibmvfc_async_crq *async;
@ -2706,7 +2726,6 @@ static irqreturn_t ibmvfc_interrupt(int irq, void *dev_instance)
int done = 0;
spin_lock_irqsave(vhost->host->host_lock, flags);
vio_disable_interrupts(to_vio_dev(vhost->dev));
while (!done) {
/* Pull all the valid messages off the CRQ */
while ((crq = ibmvfc_next_crq(vhost)) != NULL) {
@ -2734,7 +2753,6 @@ static irqreturn_t ibmvfc_interrupt(int irq, void *dev_instance)
}
spin_unlock_irqrestore(vhost->host->host_lock, flags);
return IRQ_HANDLED;
}
/**
@ -3859,6 +3877,8 @@ static int ibmvfc_init_crq(struct ibmvfc_host *vhost)
retrc = 0;
tasklet_init(&vhost->tasklet, (void *)ibmvfc_tasklet, (unsigned long)vhost);
if ((rc = request_irq(vdev->irq, ibmvfc_interrupt, 0, IBMVFC_NAME, vhost))) {
dev_err(dev, "Couldn't register irq 0x%x. rc=%d\n", vdev->irq, rc);
goto req_irq_failed;
@ -3874,6 +3894,7 @@ static int ibmvfc_init_crq(struct ibmvfc_host *vhost)
return retrc;
req_irq_failed:
tasklet_kill(&vhost->tasklet);
do {
rc = plpar_hcall_norets(H_FREE_CRQ, vdev->unit_address);
} while (rc == H_BUSY || H_IS_LONG_BUSY(rc));

1
drivers/scsi/ibmvscsi/ibmvfc.h
View File

@ -684,6 +684,7 @@ struct ibmvfc_host {
char partition_name[97];
void (*job_step) (struct ibmvfc_host *);
struct task_struct *work_thread;
struct tasklet_struct tasklet;
wait_queue_head_t init_wait_q;
wait_queue_head_t work_wait_q;
};