Hi Dexan, Stephano,
This solution has been proposed here,
Best regards,
Frédéric
On Mon, Oct 31, 2022 at 9:43 AM Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote:
On Fri, Oct 28, 2022 at 01:56:46PM -0700, Dexuan Cui wrote:
>Currently vsock_connectible_has_data() may miss a wakeup operation
>between vsock_connectible_has_data() == 0 and the prepare_to_wait().
>
>Fix the race by adding the process to the wait qeuue before checking
s/qeuue/queue
>vsock_connectible_has_data().
>
>Fixes: b3f7fd54881b ("af_vsock: separate wait data loop")
>Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
>---
> net/vmw_vsock/af_vsock.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
>diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>index d258fd43092e..03a6b5bc6ba7 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -1905,8 +1905,11 @@ static int vsock_connectible_wait_data(struct sock *sk,
> err = 0;
> transport = vsk->transport;
>
>- while ((data = "" == 0) {
>+ while (1) {
> prepare_to_wait(sk_sleep(sk), wait, TASK_INTERRUPTIBLE);
>+ data = ""> >+ if (data != 0)
>+ break;
>
> if (sk->sk_err != 0 ||
> (sk->sk_shutdown & RCV_SHUTDOWN) ||
>@@ -1937,6 +1940,8 @@ static int vsock_connectible_wait_data(struct sock *sk,
> err = -EAGAIN;
> break;
> }
>+
>+ finish_wait(sk_sleep(sk), wait);
Since we are going to call again prepare_to_wait() on top of the loop,
is finish_wait() call here really needed?
What about following what we do in vsock_accept and vsock_connect?
prepare_to_wait()
while (condition) {
...
prepare_to_wait();
}
finish_wait()
I find it a little more readable, but your solution is fine too.
Thanks,
Stefano
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