On 12/08/2016 03:29 PM, Paolo Bonzini wrote:
>
>
> On 08/12/2016 00:31, Tyrel Datwyler wrote:
>> The first byte of each CRQ entry is used to indicate whether an entry is
>> a valid response or free for the VIOS to use. After processing a
>> response the driver sets the valid byte to zero to indicate the entry is
>> now free to be reused. Add a memory barrier after this write to ensure
>> no other stores are reordered when updating the valid byte.
>>
>> Signed-off-by: Tyrel Datwyler <tyr...@linux.vnet.ibm.com>
>> ---
>> drivers/scsi/ibmvscsi/ibmvscsi.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c
>> b/drivers/scsi/ibmvscsi/ibmvscsi.c
>> index d9534ee..2f5b07e 100644
>> --- a/drivers/scsi/ibmvscsi/ibmvscsi.c
>> +++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
>> @@ -232,6 +232,7 @@ static void ibmvscsi_task(void *data)
>> while ((crq = crq_queue_next_crq(&hostdata->queue)) != NULL) {
>> ibmvscsi_handle_crq(crq, hostdata);
>> crq->valid = VIOSRP_CRQ_FREE;
>> + wmb();
>> }
>>
>> vio_enable_interrupts(vdev);
>> @@ -240,6 +241,7 @@ static void ibmvscsi_task(void *data)
>> vio_disable_interrupts(vdev);
>> ibmvscsi_handle_crq(crq, hostdata);
>> crq->valid = VIOSRP_CRQ_FREE;
>> + wmb();
>
> Should this driver use virt_wmb instead?
Both virt_wmb and wmb reduce to a lwsync instruction under PowerPC.
-Tyrel
>
> Paolo
>
>> } else {
>> done = 1;
>> }
>>
