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| author | Jeremy Allison <jra@samba.org> | 2014-06-03 10:44:19 -0700 |
|---|---|---|
| committer | Jeremy Allison <jra@samba.org> | 2014-06-07 03:15:14 +0200 |
| commit | 536c799f00d7bdd6a574b6bdbc0e9c742eeef8b5 (patch) | |
| tree | f59af2726545ce9fd8944b5ab07553af1a41b242 | |
| parent | 463311422ca1caad2e228deb630e9d12e212fae1 (diff) | |
| download | samba-536c799f00d7bdd6a574b6bdbc0e9c742eeef8b5.tar.gz samba-536c799f00d7bdd6a574b6bdbc0e9c742eeef8b5.tar.xz samba-536c799f00d7bdd6a574b6bdbc0e9c742eeef8b5.zip | |
lib: tevent: make TEVENT_SIG_INCREMENT atomic.
On arm platforms incrementing a variable is not
an atomic operation, so may be interrupted by
signal processing (if a signal interrupts another
signal handler).
Use compiler built-ins to make this atomic.
__sync_fetch_and_add() works on gcc, llvm,
IBM xlC on AIX, and Intel icc (10.1 and
above).
atomic_add_32() works on Oracle Solaris.
Based on an inital patch from kamei@osstech.co.jp.
Bug #10640 - smbd is not responding - tevent_common_signal_handler() increments non-atomic variables
https://bugzilla.samba.org/show_bug.cgi?id=10640
Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Volker Lendecke <Volker.Lendecke@SerNet.DE>
| -rw-r--r-- | lib/replace/replace.h | 5 | ||||
| -rw-r--r-- | lib/replace/wscript | 25 | ||||
| -rw-r--r-- | lib/tevent/tevent_signal.c | 6 |
3 files changed, 36 insertions, 0 deletions
diff --git a/lib/replace/replace.h b/lib/replace/replace.h index f940898e4b9..bc40bf012e6 100644 --- a/lib/replace/replace.h +++ b/lib/replace/replace.h @@ -904,4 +904,9 @@ bool nss_wrapper_hosts_enabled(void); bool socket_wrapper_enabled(void); bool uid_wrapper_enabled(void); +/* Needed for Solaris atomic_add_XX functions. */ +#if defined(HAVE_SYS_ATOMIC_H) +#include <sys/atomic.h> +#endif + #endif /* _LIBREPLACE_REPLACE_H */ diff --git a/lib/replace/wscript b/lib/replace/wscript index a26de0f8bae..22dd1322a21 100644 --- a/lib/replace/wscript +++ b/lib/replace/wscript @@ -110,6 +110,7 @@ struct foo bar = { .y = 'X', .x = 1 }; conf.CHECK_HEADERS('sys/extattr.h sys/ea.h sys/proplist.h sys/cdefs.h') conf.CHECK_HEADERS('utmp.h utmpx.h lastlog.h malloc.h') conf.CHECK_HEADERS('syscall.h sys/syscall.h inttypes.h') + conf.CHECK_HEADERS('sys/atomic.h') # Check for process set name support conf.CHECK_CODE(''' @@ -229,6 +230,30 @@ struct foo bar = { .y = 'X', .x = 1 }; msg="Checking whether we have ucontext_t", headers='signal.h sys/ucontext.h') + # Check for atomic builtins. */ + conf.CHECK_CODE(''' + int main(void) { + int i; + (void)__sync_fetch_and_add(&i, 1); + return 0; + } + ''', + 'HAVE___SYNC_FETCH_AND_ADD', + msg='Checking for __sync_fetch_and_add compiler builtin') + + conf.CHECK_CODE(''' + #include <stdint.h> + #include <sys/atomic.h> + int main(void) { + int32_t i; + atomic_add_32(&i, 1); + return 0; + } + ''', + 'HAVE_ATOMIC_ADD_32', + headers='stdint.h sys/atomic.h', + msg='Checking for atomic_add_32 compiler builtin') + # these may be builtins, so we need the link=False strategy conf.CHECK_FUNCS('strdup memmem printf memset memcpy memmove strcpy strncpy bzero', link=False) diff --git a/lib/tevent/tevent_signal.c b/lib/tevent/tevent_signal.c index 1ff487256e9..b54da2ede82 100644 --- a/lib/tevent/tevent_signal.c +++ b/lib/tevent/tevent_signal.c @@ -52,7 +52,13 @@ struct tevent_sigcounter { uint32_t seen; }; +#if defined(HAVE___SYNC_FETCH_AND_ADD) +#define TEVENT_SIG_INCREMENT(s) __sync_fetch_and_add(&((s).count), 1) +#elif defined(HAVE_ATOMIC_ADD_32) +#define TEVENT_SIG_INCREMENT(s) atomic_add_32(&((s).count), 1) +#else #define TEVENT_SIG_INCREMENT(s) (s).count++ +#endif #define TEVENT_SIG_SEEN(s, n) (s).seen += (n) #define TEVENT_SIG_PENDING(s) ((s).seen != (s).count) |