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| author | Brian King <brking@linux.vnet.ibm.com> | 2010-04-20 23:21:33 +0400 |
|---|---|---|
| committer | James Bottomley <James.Bottomley@suse.de> | 2010-05-02 19:03:03 +0400 |
| commit | f5832fa2f8dc39adcf3ae348d2d6383163235e79 (patch) | |
| tree | 1fea25c52248b213dd44d2ad693959ff29d56495 /drivers/scsi/ibmvscsi | |
| parent | 859e816704b4139d15b1ec6a3505f12faef5333a (diff) | |
| download | linux-f5832fa2f8dc39adcf3ae348d2d6383163235e79.tar.xz | |
[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 <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Diffstat (limited to 'drivers/scsi/ibmvscsi')
| -rw-r--r-- | drivers/scsi/ibmvscsi/ibmvfc.c | 6 |
1 files changed, 6 insertions, 0 deletions
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; } |