2020-03-03 22:24:12

by Dongli Zhang

Subject: [PATCH v3 2/2] xenbus: req->err should be updated before req->state

This patch adds the barrier to guarantee that req->err is always updated
before req->state.

Otherwise, read_reply() would not return ERR_PTR(req->err) but
req->body, when process_writes()->xb_write() is failed.

Signed-off-by: Dongli Zhang <[email protected]>
---
drivers/xen/xenbus/xenbus_comms.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/xen/xenbus/xenbus_comms.c b/drivers/xen/xenbus/xenbus_comms.c
index 852ed161fc2a..eb5151fc8efa 100644
--- a/drivers/xen/xenbus/xenbus_comms.c
+++ b/drivers/xen/xenbus/xenbus_comms.c
@@ -397,6 +397,8 @@ static int process_writes(void)
if (state.req->state == xb_req_state_aborted)
kfree(state.req);
else {
+ /* write err, then update state */
+ virt_wmb();
state.req->state = xb_req_state_got_reply;
wake_up(&state.req->wq);
}
--
2.17.1

2020-03-04 13:51:33

by Julien Grall

Subject: Re: [PATCH v3 2/2] xenbus: req->err should be updated before req->state

Hi,

On 03/03/2020 22:14, Dongli Zhang wrote:
> This patch adds the barrier to guarantee that req->err is always updated
> before req->state.
>
> Otherwise, read_reply() would not return ERR_PTR(req->err) but
> req->body, when process_writes()->xb_write() is failed.
>
> Signed-off-by: Dongli Zhang <[email protected]>

Reviewed-by: Julien Grall <[email protected]>

Cheers,

---
Julien Grall

2020-03-06 11:15:19

by Boris Ostrovsky

Subject: Re: [PATCH v3 2/2] xenbus: req->err should be updated before req->state

On 3/3/20 5:14 PM, Dongli Zhang wrote:
> This patch adds the barrier to guarantee that req->err is always updated
> before req->state.
>
> Otherwise, read_reply() would not return ERR_PTR(req->err) but
> req->body, when process_writes()->xb_write() is failed.
>
> Signed-off-by: Dongli Zhang <[email protected]>

Applied to for-linus-5.6b.

-boris