Revert "vsock: Fix blocking ops call in prepare_to_wait"
This reverts commit 5988818008
("vsock: Fix
blocking ops call in prepare_to_wait")
The commit reverted with this patch caused us to potentially miss wakeups.
Since the condition is not checked between the prepare_to_wait and the
schedule(), if a wakeup happens after the condition is checked but before
the sleep happens, we will miss it. ( A description of the problem can be
found here: http://www.makelinux.net/ldd3/chp-6-sect-2 ).
By reverting the patch, the behaviour is still incorrect (since we
shouldn't sleep between the prepare_to_wait and the schedule) but at least
it will not miss wakeups.
The next patch in the series actually fixes the behaviour.
Signed-off-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
9a0384c020
commit
6f57e56a15
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@ -1557,6 +1557,8 @@ static int vsock_stream_sendmsg(struct socket *sock, struct msghdr *msg,
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if (err < 0)
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if (err < 0)
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goto out;
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goto out;
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prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
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while (total_written < len) {
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while (total_written < len) {
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ssize_t written;
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ssize_t written;
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@ -1576,9 +1578,7 @@ static int vsock_stream_sendmsg(struct socket *sock, struct msghdr *msg,
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goto out_wait;
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goto out_wait;
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release_sock(sk);
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release_sock(sk);
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prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
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timeout = schedule_timeout(timeout);
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timeout = schedule_timeout(timeout);
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finish_wait(sk_sleep(sk), &wait);
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lock_sock(sk);
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lock_sock(sk);
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if (signal_pending(current)) {
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if (signal_pending(current)) {
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err = sock_intr_errno(timeout);
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err = sock_intr_errno(timeout);
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@ -1588,6 +1588,8 @@ static int vsock_stream_sendmsg(struct socket *sock, struct msghdr *msg,
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goto out_wait;
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goto out_wait;
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}
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}
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prepare_to_wait(sk_sleep(sk), &wait,
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TASK_INTERRUPTIBLE);
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}
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}
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/* These checks occur both as part of and after the loop
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/* These checks occur both as part of and after the loop
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@ -1633,6 +1635,7 @@ static int vsock_stream_sendmsg(struct socket *sock, struct msghdr *msg,
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out_wait:
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out_wait:
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if (total_written > 0)
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if (total_written > 0)
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err = total_written;
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err = total_written;
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finish_wait(sk_sleep(sk), &wait);
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out:
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out:
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release_sock(sk);
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release_sock(sk);
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return err;
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return err;
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@ -1713,6 +1716,7 @@ vsock_stream_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
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if (err < 0)
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if (err < 0)
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goto out;
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goto out;
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prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
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while (1) {
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while (1) {
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s64 ready = vsock_stream_has_data(vsk);
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s64 ready = vsock_stream_has_data(vsk);
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@ -1723,7 +1727,7 @@ vsock_stream_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
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*/
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*/
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err = -ENOMEM;
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err = -ENOMEM;
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goto out;
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goto out_wait;
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} else if (ready > 0) {
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} else if (ready > 0) {
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ssize_t read;
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ssize_t read;
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@ -1746,7 +1750,7 @@ vsock_stream_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
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vsk, target, read,
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vsk, target, read,
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!(flags & MSG_PEEK), &recv_data);
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!(flags & MSG_PEEK), &recv_data);
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if (err < 0)
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if (err < 0)
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goto out;
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goto out_wait;
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if (read >= target || flags & MSG_PEEK)
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if (read >= target || flags & MSG_PEEK)
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break;
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break;
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@ -1769,9 +1773,7 @@ vsock_stream_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
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break;
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break;
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release_sock(sk);
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release_sock(sk);
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prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
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timeout = schedule_timeout(timeout);
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timeout = schedule_timeout(timeout);
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finish_wait(sk_sleep(sk), &wait);
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lock_sock(sk);
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lock_sock(sk);
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if (signal_pending(current)) {
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if (signal_pending(current)) {
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@ -1781,6 +1783,9 @@ vsock_stream_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
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err = -EAGAIN;
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err = -EAGAIN;
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break;
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break;
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}
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}
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prepare_to_wait(sk_sleep(sk), &wait,
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TASK_INTERRUPTIBLE);
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}
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}
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}
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}
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@ -1811,6 +1816,8 @@ vsock_stream_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
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err = copied;
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err = copied;
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}
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}
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out_wait:
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finish_wait(sk_sleep(sk), &wait);
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out:
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out:
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release_sock(sk);
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release_sock(sk);
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return err;
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return err;
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