[ovs-dev] [PATCH] Use pthread_sigmask() in place of sigprocmask(), for thread safety.

[Andy Zhou]

Looks good.


On Wed, May 1, 2013 at 11:38 AM, Ben Pfaff <blp at nicira.com> wrote:

> POSIX says that multithreaded programs must not use sigprocmask() but must
> use pthread_sigmask() instead.  This commit makes that replacement.
>
> The actual use of signals in Open vSwitch is still not thread safe
> following this commit, but this change is a necessary prerequisite for
> fixing the other problems.
>
> Signed-off-by: Ben Pfaff <blp at nicira.com>
> ---
>  lib/process.c |    6 +++---
>  lib/signals.c |    9 +++++----
>  lib/signals.h |    4 ++--
>  lib/timeval.c |    4 ++--
>  4 files changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/lib/process.c b/lib/process.c
> index 795a136..9fe742c 100644
> --- a/lib/process.c
> +++ b/lib/process.c
> @@ -640,7 +640,7 @@ sigchld_is_blocked(void)
>  {
>      sigset_t sigs;
>
> -    xsigprocmask(SIG_SETMASK, NULL, &sigs);
> +    xpthread_sigmask(SIG_SETMASK, NULL, &sigs);
>      return sigismember(&sigs, SIGCHLD);
>  }
>
> @@ -651,11 +651,11 @@ block_sigchld(sigset_t *oldsigs)
>
>      sigemptyset(&sigchld);
>      sigaddset(&sigchld, SIGCHLD);
> -    xsigprocmask(SIG_BLOCK, &sigchld, oldsigs);
> +    xpthread_sigmask(SIG_BLOCK, &sigchld, oldsigs);
>  }
>
>  static void
>  unblock_sigchld(const sigset_t *oldsigs)
>  {
> -    xsigprocmask(SIG_SETMASK, oldsigs, NULL);
> +    xpthread_sigmask(SIG_SETMASK, oldsigs, NULL);
>  }
> diff --git a/lib/signals.c b/lib/signals.c
> index 06c2e75..f31bc52 100644
> --- a/lib/signals.c
> +++ b/lib/signals.c
> @@ -1,5 +1,5 @@
>  /*
> - * Copyright (c) 2008, 2009, 2011, 2012 Nicira, Inc.
> + * Copyright (c) 2008, 2009, 2011, 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.
> @@ -168,9 +168,10 @@ xsigaction(int signum, const struct sigaction *new,
> struct sigaction *old)
>  }
>
>  void
> -xsigprocmask(int how, const sigset_t *new, sigset_t *old)
> +xpthread_sigmask(int how, const sigset_t *new, sigset_t *old)
>  {
> -    if (sigprocmask(how, new, old)) {
> -        VLOG_FATAL("sigprocmask failed (%s)", strerror(errno));
> +    int error = pthread_sigmask(how, new, old);
> +    if (error) {
> +        VLOG_FATAL("pthread_sigmask failed (%s)", strerror(error));
>      }
>  }
> diff --git a/lib/signals.h b/lib/signals.h
> index ac96b0f..641bcbb 100644
> --- a/lib/signals.h
> +++ b/lib/signals.h
> @@ -1,5 +1,5 @@
>  /*
> - * Copyright (c) 2008, 2011 Nicira, Inc.
> + * Copyright (c) 2008, 2011, 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.
> @@ -31,6 +31,6 @@ void signal_wait(struct signal *);
>  const char *signal_name(int signum);
>
>  void xsigaction(int signum, const struct sigaction *, struct sigaction
> *old);
> -void xsigprocmask(int how, const sigset_t *, sigset_t *old);
> +void xpthread_sigmask(int how, const sigset_t *, sigset_t *old);
>
>  #endif /* signals.h */
> diff --git a/lib/timeval.c b/lib/timeval.c
> index 163de1e..f687c96 100644
> --- a/lib/timeval.c
> +++ b/lib/timeval.c
> @@ -454,13 +454,13 @@ block_sigalrm(sigset_t *oldsigs)
>      sigset_t sigalrm;
>      sigemptyset(&sigalrm);
>      sigaddset(&sigalrm, SIGALRM);
> -    xsigprocmask(SIG_BLOCK, &sigalrm, oldsigs);
> +    xpthread_sigmask(SIG_BLOCK, &sigalrm, oldsigs);
>  }
>
>  static void
>  unblock_sigalrm(const sigset_t *oldsigs)
>  {
> -    xsigprocmask(SIG_SETMASK, oldsigs, NULL);
> +    xpthread_sigmask(SIG_SETMASK, oldsigs, NULL);
>  }
>
>  long long int
> --
> 1.7.2.5
>
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> dev at openvswitch.org
> http://openvswitch.org/mailman/listinfo/dev
>
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