From 0e4d4dd89170d47a662f1cd0de1b4f3a5dbc1f2d Mon Sep 17 00:00:00 2001 From: Denis Vlasenko Date: Mon, 1 Dec 2008 15:31:22 +0000 Subject: optimize signal mask ops. comment out "impossible" errors text data bss dec hex filename - 1179 13 2 1194 4aa libc/misc/syslog/syslog.o + 1165 13 2 1180 49c libc/misc/syslog/syslog.o - 435 4 0 439 1b7 libc/pwd_grp/lckpwdf.o + 393 4 0 397 18d libc/pwd_grp/lckpwdf.o - 38 0 0 38 26 libc/signal/sigandset.o + 32 0 0 32 20 libc/signal/sigandset.o - 63 0 0 63 3f libc/signal/sigblock.o + 56 0 0 56 38 libc/signal/sigblock.o - 22 0 0 22 16 libc/signal/sigempty.o + 20 0 0 20 14 libc/signal/sigempty.o - 25 0 0 25 19 libc/signal/sigfillset.o + 20 0 0 20 14 libc/signal/sigfillset.o - 34 0 0 34 22 libc/signal/sigisempty.o + 16 0 0 16 10 libc/signal/sigisempty.o - 38 0 0 38 26 libc/signal/sigorset.o + 32 0 0 32 20 libc/signal/sigorset.o - 119 0 0 119 77 libc/signal/sigpause.o + 113 0 0 113 71 libc/signal/sigpause.o - 215 0 0 215 d7 libc/signal/sigset.o + 211 0 0 211 d3 libc/signal/sigset.o - 63 0 0 63 3f libc/signal/sigsetmask.o + 56 0 0 56 38 libc/signal/sigsetmask.o - 194 0 1 195 c3 libc/stdlib/abort.o + 183 0 1 184 b8 libc/stdlib/abort.o - 323 0 0 323 143 libc/unistd/sleep.o + 309 0 0 309 135 libc/unistd/sleep.o --- libc/pwd_grp/lckpwdf.c | 42 +++++++++++++++++++++++------------------- 1 file changed, 23 insertions(+), 19 deletions(-) (limited to 'libc/pwd_grp') diff --git a/libc/pwd_grp/lckpwdf.c b/libc/pwd_grp/lckpwdf.c index a9601d45d..41987ca5d 100644 --- a/libc/pwd_grp/lckpwdf.c +++ b/libc/pwd_grp/lckpwdf.c @@ -39,11 +39,9 @@ /* libc_hidden_proto(sigemptyset) */ /* libc_hidden_proto(alarm) */ -/* How long to wait for getting the lock before returning with an - error. */ +/* How long to wait for getting the lock before returning with an error. */ #define TIMEOUT 15 /* sec */ - /* File descriptor for lock file. */ static int lock_fd = -1; @@ -51,7 +49,6 @@ static int lock_fd = -1; #include __UCLIBC_MUTEX_STATIC(mylock, PTHREAD_MUTEX_INITIALIZER); - /* Prototypes for local functions. */ static void noop_handler (int __sig); @@ -82,33 +79,39 @@ lckpwdf (void) } /* Make sure file gets correctly closed when process finished. */ - flags = fcntl (lock_fd, F_GETFD, 0); + flags = fcntl (lock_fd, F_GETFD); +#if 0 /* never fails */ if (flags == -1) { /* Cannot get file flags. */ close(lock_fd); lock_fd = -1; goto DONE; } - flags |= FD_CLOEXEC; /* Close on exit. */ +#endif + flags |= FD_CLOEXEC; +#if 1 + fcntl (lock_fd, F_SETFD, flags); +#else /* never fails */ if (fcntl (lock_fd, F_SETFD, flags) < 0) { /* Cannot set new flags. */ close(lock_fd); lock_fd = -1; goto DONE; } - +#endif /* Now we have to get exclusive write access. Since multiple process could try this we won't stop when it first fails. Instead we set a timeout for the system call. Once the timer expires it is likely that there are some problems which cannot be - resolved by waiting. + resolved by waiting. (sa_flags have no SA_RESTART. Thus SIGALRM + will EINTR fcntl(F_SETLKW) It is important that we don't change the signal state. We must restore the old signal behaviour. */ memset (&new_act, '\0', sizeof (struct sigaction)); new_act.sa_handler = noop_handler; - sigfillset (&new_act.sa_mask); - new_act.sa_flags = 0ul; + __sigfillset (&new_act.sa_mask); + /* new_act.sa_flags = 0; */ /* Install new action handler for alarm and save old. */ if (sigaction (SIGALRM, &new_act, &saved_act) < 0) { @@ -119,34 +122,35 @@ lckpwdf (void) } /* Now make sure the alarm signal is not blocked. */ - sigemptyset (&new_set); + __sigemptyset (&new_set); sigaddset (&new_set, SIGALRM); +#if 1 + sigprocmask (SIG_UNBLOCK, &new_set, &saved_set); +#else /* never fails */ if (sigprocmask (SIG_UNBLOCK, &new_set, &saved_set) < 0) { sigaction (SIGALRM, &saved_act, NULL); close(lock_fd); lock_fd = -1; goto DONE; } +#endif /* Start timer. If we cannot get the lock in the specified time we get a signal. */ alarm (TIMEOUT); /* Try to get the lock. */ - memset (&fl, '\0', sizeof (struct flock)); - fl.l_type = F_WRLCK; - fl.l_whence = SEEK_SET; + memset (&fl, '\0', sizeof (fl)); + if (F_WRLCK) + fl.l_type = F_WRLCK; + if (SEEK_SET) + fl.l_whence = SEEK_SET; result = fcntl (lock_fd, F_SETLKW, &fl); /* Clear alarm. */ alarm (0); - /* Restore old set of handled signals. We don't need to know - about the current one.*/ sigprocmask (SIG_SETMASK, &saved_set, NULL); - - /* Restore old action handler for alarm. We don't need to know - about the current one. */ sigaction (SIGALRM, &saved_act, NULL); if (result < 0) { -- cgit v1.2.3