Commit 039a0898 authored by Brian King's avatar Brian King Committed by James Bottomley
Browse files

[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: default avatarBrian King <brking@linux.vnet.ibm.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
parent 8fe74cf0

drivers/scsi/ibmvscsi/ibmvfc.c

+23 −2
Original line number Diff line number Diff line
@@ -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));

drivers/scsi/ibmvscsi/ibmvfc.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

};