scsi: hisi_sas: add memory barrier in task delivery function

scsi: hisi_sas: add memory barrier in task delivery function

BugLink: https://bugs.launchpad.net/bugs/1794156
In task start delivery function, we need to add a memory barrier to prevent
re-ordering of reading memory by hardware. Because the slot data is set in
task prepare function and it could be running in another CPU.

This patch adds an memory barrier after s->ready is read in the task start
delivery function, and uses WRITE_ONCE() in the places where s->ready is
set to ensure that the compiler does not re-order.

Signed-off-by: Xiaofei Tan <tanxiaofei@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
(cherry picked from commit 1c09b663168bb5fd8562234976b76115f2aebe91)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>