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@xxxxxxxxxxxxxxxxxx>
---
drivers/scsi/ibmvscsi/ibmvfc.c | 25 +++++++++++++++++++++++--
drivers/scsi/ibmvscsi/ibmvfc.h | 1 +
2 files changed, 24 insertions(+), 2 deletions(-)
diff -puN drivers/scsi/ibmvscsi/ibmvfc.h~ibmvfc_tasklet drivers/scsi/ibmvscsi/ibmvfc.h
--- linux-2.6/drivers/scsi/ibmvscsi/ibmvfc.h~ibmvfc_tasklet 2009-02-05 11:06:05.000000000 -0600
+++ linux-2.6-bjking1/drivers/scsi/ibmvscsi/ibmvfc.h 2009-02-05 11:07:03.000000000 -0600
@@ -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;
};
diff -puN drivers/scsi/ibmvscsi/ibmvfc.c~ibmvfc_tasklet drivers/scsi/ibmvscsi/ibmvfc.c
--- linux-2.6/drivers/scsi/ibmvscsi/ibmvfc.c~ibmvfc_tasklet 2009-02-05 11:06:10.000000000 -0600
+++ linux-2.6-bjking1/drivers/scsi/ibmvscsi/ibmvfc.c 2009-02-05 11:23:12.000000000 -0600
@@ -640,6 +640,7 @@ static void ibmvfc_release_crq_queue(str
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_cr
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
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
}
spin_unlock_irqrestore(vhost->host->host_lock, flags);
- return IRQ_HANDLED;
}
/**
@@ -3859,6 +3877,8 @@ static int ibmvfc_init_crq(struct ibmvfc
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
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));
_
--
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