From f5832fa2f8dc39adcf3ae348d2d6383163235e79 Mon Sep 17 00:00:00 2001 From: Brian King Date: Tue, 20 Apr 2010 14:21:33 -0500 Subject: [PATCH] [SCSI] ibmvfc: Fix command completion handling Commands which are completed by the VIOS are placed on a CRQ in kernel memory for the ibmvfc driver to process. Each CRQ entry is 16 bytes. The ibmvfc driver reads the first 8 bytes to check if the entry is valid, then reads the next 8 bytes to get the handle, which is a pointer the completed command. This fixes an issue seen on Power 7 where the processor reordered the loads from memory, resulting in processing command completion with a stale handle. This could result in command timeouts, and also early completion of commands. Signed-off-by: Brian King Signed-off-by: James Bottomley --- drivers/scsi/ibmvscsi/ibmvfc.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c index c2eea711a5ce..9372169374e2 100644 --- a/drivers/scsi/ibmvscsi/ibmvfc.c +++ b/drivers/scsi/ibmvscsi/ibmvfc.c @@ -3013,6 +3013,7 @@ static struct ibmvfc_async_crq *ibmvfc_next_async_crq(struct ibmvfc_host *vhost) if (crq->valid & 0x80) { if (++async_crq->cur == async_crq->size) async_crq->cur = 0; + rmb(); } else crq = NULL; @@ -3035,6 +3036,7 @@ static struct ibmvfc_crq *ibmvfc_next_crq(struct ibmvfc_host *vhost) if (crq->valid & 0x80) { if (++queue->cur == queue->size) queue->cur = 0; + rmb(); } else crq = NULL; @@ -3083,12 +3085,14 @@ static void ibmvfc_tasklet(void *data) while ((async = ibmvfc_next_async_crq(vhost)) != NULL) { ibmvfc_handle_async(async, vhost); async->valid = 0; + wmb(); } /* Pull all the valid messages off the CRQ */ while ((crq = ibmvfc_next_crq(vhost)) != NULL) { ibmvfc_handle_crq(crq, vhost); crq->valid = 0; + wmb(); } vio_enable_interrupts(vdev); @@ -3096,10 +3100,12 @@ static void ibmvfc_tasklet(void *data) vio_disable_interrupts(vdev); ibmvfc_handle_async(async, vhost); async->valid = 0; + wmb(); } else if ((crq = ibmvfc_next_crq(vhost)) != NULL) { vio_disable_interrupts(vdev); ibmvfc_handle_crq(crq, vhost); crq->valid = 0; + wmb(); } else done = 1; } -- 2.20.1