[dm-devel] [PATCH] libmultipath, multipathd: Rework SIGPIPE handling

[Christophe Varoqui]

Merged.
Thanks.

On Tue, Aug 16, 2016 at 10:08 PM, Bart Van Assche <
bart.vanassche at sandisk.com> wrote:

> The behavior we want is as follows:
> * If stdout or stderr is closed then SIGPIPE causes termination.
> * Sending data to a socket that has been closed by the receiver
>   does not cause multipathd to stop.
>
> Hence unblock SIGPIPE and use MSG_NOSIGNAL when sending data over
> a socket.
>
> Signed-off-by: Bart Van Assche <bart.vanassche at sandisk.com>
> Cc: Benjamin Marzinski <bmarzins at redhat.com>
> Cc: Gris Ge <fge at redhat.com>
> ---
>  libmpathcmd/mpath_cmd.c |  4 ++--
>  libmultipath/uxsock.c   | 17 ++---------------
>  multipathd/main.c       |  8 +-------
>  3 files changed, 5 insertions(+), 24 deletions(-)
>
> diff --git a/libmpathcmd/mpath_cmd.c b/libmpathcmd/mpath_cmd.c
> index c058479..667a2dc 100644
> --- a/libmpathcmd/mpath_cmd.c
> +++ b/libmpathcmd/mpath_cmd.c
> @@ -33,7 +33,7 @@ static ssize_t read_all(int fd, void *buf, size_t len,
> unsigned int timeout)
>                         return -1;
>                 } else if (!pfd.revents & POLLIN)
>                         continue;
> -               n = read(fd, buf, len);
> +               n = recv(fd, buf, len, 0);
>                 if (n < 0) {
>                         if ((errno == EINTR) || (errno == EAGAIN))
>                                 continue;
> @@ -56,7 +56,7 @@ static size_t write_all(int fd, const void *buf, size_t
> len)
>         size_t total = 0;
>
>         while (len) {
> -               ssize_t n = write(fd, buf, len);
> +               ssize_t n = send(fd, buf, len, MSG_NOSIGNAL);
>                 if (n < 0) {
>                         if ((errno == EINTR) || (errno == EAGAIN))
>                                 continue;
> diff --git a/libmultipath/uxsock.c b/libmultipath/uxsock.c
> index 775e278..880257f 100644
> --- a/libmultipath/uxsock.c
> +++ b/libmultipath/uxsock.c
> @@ -81,7 +81,7 @@ size_t write_all(int fd, const void *buf, size_t len)
>         size_t total = 0;
>
>         while (len) {
> -               ssize_t n = write(fd, buf, len);
> +               ssize_t n = send(fd, buf, len, MSG_NOSIGNAL);
>                 if (n < 0) {
>                         if ((errno == EINTR) || (errno == EAGAIN))
>                                 continue;
> @@ -138,20 +138,7 @@ ssize_t read_all(int fd, void *buf, size_t len,
> unsigned int timeout)
>   */
>  int send_packet(int fd, const char *buf)
>  {
> -       int ret = 0;
> -       sigset_t set, old;
> -
> -       /* Block SIGPIPE */
> -       sigemptyset(&set);
> -       sigaddset(&set, SIGPIPE);
> -       pthread_sigmask(SIG_BLOCK, &set, &old);
> -
> -       ret = mpath_send_cmd(fd, buf);
> -
> -       /* And unblock it again */
> -       pthread_sigmask(SIG_SETMASK, &old, NULL);
> -
> -       return ret;
> +       return mpath_send_cmd(fd, buf);
>  }
>
>  /*
> diff --git a/multipathd/main.c b/multipathd/main.c
> index 54abfef..2be6cb2 100644
> --- a/multipathd/main.c
> +++ b/multipathd/main.c
> @@ -2125,18 +2125,12 @@ sigusr2 (int sig)
>  static void
>  signal_init(void)
>  {
> -       sigset_t set;
> -
> -       sigemptyset(&set);
> -       sigaddset(&set, SIGPIPE);
> -       pthread_sigmask(SIG_SETMASK, &set, NULL);
> -
>         signal_set(SIGHUP, sighup);
>         signal_set(SIGUSR1, sigusr1);
>         signal_set(SIGUSR2, sigusr2);
>         signal_set(SIGINT, sigend);
>         signal_set(SIGTERM, sigend);
> -       signal(SIGPIPE, SIG_IGN);
> +       signal_set(SIGPIPE, sigend);
>  }
>
>  static void
> --
> 2.9.2
>
>
>
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