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authorBrian King <brking@linux.vnet.ibm.com>2010-04-20 14:21:33 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2010-08-13 13:20:24 -0700
commitd006b64edff0fa5aea86696cec70fd3a56542b17 (patch)
treeb697353bf103fd95f7d8d84b1dce9d809661e511
parentb92f44353fdc526df58a563a6c9279293eb607c7 (diff)
ibmvfc: Fix command completion handling
commit f5832fa2f8dc39adcf3ae348d2d6383163235e79 upstream. 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 <brking@linux.vnet.ibm.com> Signed-off-by: James Bottomley <James.Bottomley@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/scsi/ibmvscsi/ibmvfc.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
index bb2c696c006a..4a0a0c010b60 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc.c
@@ -2720,6 +2720,7 @@ 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;
@@ -2742,6 +2743,7 @@ 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;
@@ -2790,12 +2792,14 @@ 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);
@@ -2803,10 +2807,12 @@ 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;
}