On 09/15/2011 12:22 PM, Laszlo Ersek wrote:
Make variables volatile ("sig_atomic_t" should cover "int" and "pid_t").Also replace calls to functions that are not required to be async-signal-safe [1]. (I haven't checked if any signal masks and/or previous suspension of the interrupted thread keep the current calls safe.) termsig_handler() -> qemu_system_killed(): shutdown_signal, shutdown_pid, no_shutdown [2] -> qemu_system_shutdown_request(): shutdown_requested -> qemu_notify_event() -> qemu_event_increment(): fprintf(), strerror(), exit() [1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04_03_03 [2] http://lists.nongnu.org/archive/html/qemu-devel/2011-09/msg01757.html "checkpatch.pl" warned four times about "volatile", and considered the zero-initialization of "no_shutdown" (which has static storage duration) an error. Build tested only. Please CC me on any followup, I'm not subscribed. Thank you. Signed-off-by: Laszlo Ersek<ler...@redhat.com> --- cpus.c | 13 ++++++++++--- sysemu.h | 2 +- vl.c | 6 +++--- 3 files changed, 14 insertions(+), 7 deletions(-) diff --git a/cpus.c b/cpus.c index 54c188c..ed51247 100644 --- a/cpus.c +++ b/cpus.c @@ -289,9 +289,16 @@ static void qemu_event_increment(void) /* EAGAIN is fine, a read must be pending. */ if (ret< 0&& errno != EAGAIN) { - fprintf(stderr, "qemu_event_increment: write() failed: %s\n", - strerror(errno)); - exit (1); + int len; + char buf[128]; + + /* Don't bother with strerror_[rl]. Make a single attempt to write. */ + len = snprintf(buf, sizeof buf, + "qemu_event_increment: write() failed: %d\n", errno);
I don't think you can rely on snprintf being signal safe. I think you should just exit on failure.
OpenBSD lists snprintf as signal safe, but "probably not on other systems." Regards, Anthony Liguori
