Acked-by: Ethan Jackson <et...@nicira.com>
On Thu, Jan 10, 2013 at 5:23 PM, Ben Pfaff <b...@nicira.com> wrote:
> The following call stack was possible:
>
> poll_block()
> -> vlog
> -> worker_send_iovec()
> -> poll_block()
>
> which caused corruption because poll_block() is not reentrant.
>
> Bug #14616.
> Signed-off-by: Ben Pfaff <b...@nicira.com>
> ---
> lib/worker.c | 20 +++++++++++++++++---
> 1 files changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/lib/worker.c b/lib/worker.c
> index f2b896e..b281d70 100644
> --- a/lib/worker.c
> +++ b/lib/worker.c
> @@ -1,4 +1,4 @@
> -/* Copyright (c) 2012 Nicira, Inc.
> +/* Copyright (c) 2012, 2013 Nicira, Inc.
> *
> * Licensed under the Apache License, Version 2.0 (the "License");
> * you may not use this file except in compliance with the License.
> @@ -198,6 +198,7 @@ worker_send_iovec(const struct iovec iovs[], size_t
> n_iovs,
> size_t sent = 0;
>
> for (;;) {
> + struct pollfd pfd;
> int error;
>
> /* Try to send the rest of the request. */
> @@ -210,8 +211,21 @@ worker_send_iovec(const struct iovec iovs[], size_t
> n_iovs,
> /* Process replies to avoid deadlock. */
> worker_run();
>
> - poll_fd_wait(client_sock, POLLIN | POLLOUT);
> - poll_block();
> + /* Wait for 'client_sock' to become ready before trying again. We
> + * can't use poll_block() because it sometimes calls into vlog,
> which
> + * calls indirectly into worker_send_iovec(). To be usable here,
> + * poll_block() would therefore need to be reentrant, but it isn't
> + * (calling it recursively causes memory corruption and an
> eventual
> + * crash). */
> + pfd.fd = client_sock;
> + pfd.events = POLLIN | POLLOUT;
> + do {
> + error = poll(&pfd, 1, -1) < 0 ? errno : 0;
> + } while (error == EINTR);
> + if (error) {
> + worker_broke();
> + VLOG_ABORT("poll failed (%s)", strerror(error));
> + }
> }
> }
>
> --
> 1.7.2.5
>
> _______________________________________________
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> dev@openvswitch.org
> http://openvswitch.org/mailman/listinfo/dev
>
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