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 = vsock_connectible_has_data(vsk)) == 0) {
+ while (1) {
prepare_to_wait(sk_sleep(sk), wait, TASK_INTERRUPTIBLE);
+ data = vsock_connectible_has_data(vsk);
+ 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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