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authorDenys Vlasenko <vda.linux@googlemail.com>2009-05-25 14:38:32 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2009-05-25 14:38:32 (GMT)
commit8d7be232a39c6fb85b6870d1a705ceca48bed869 (patch)
treec7d2c47f8b18f02fa13bf1418a5139a3e0f00817
parentbf2af9acb28ed6d8bbe351d669daaa140d0239f0 (diff)
downloadbusybox-8d7be232a39c6fb85b6870d1a705ceca48bed869.tar.gz
busybox-8d7be232a39c6fb85b6870d1a705ceca48bed869.tar.bz2
hush: fix SIGCHLD counting code, but keep it disabled for now.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--shell/hush.c85
1 files changed, 66 insertions, 19 deletions
diff --git a/shell/hush.c b/shell/hush.c
index acc8ef9..fd839d0 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -69,7 +69,7 @@
#endif
-/* Debug build knobs */
+/* Build knobs */
#define LEAK_HUNTING 0
#define BUILD_AS_NOMMU 0
/* Enable/disable sanity checks. Ok to enable in production,
@@ -77,6 +77,13 @@
* Keeping 1 for now even in released versions.
*/
#define HUSH_DEBUG 1
+/* Slightly bigger (+200 bytes), but faster hush.
+ * So far it only enables a trick with counting SIGCHLDs and forks,
+ * which allows us to do fewer waitpid's.
+ * (we can detect a case where neither forks were done nor SIGCHLDs happened
+ * and therefore waitpid will return the same result as last time)
+ */
+#define ENABLE_HUSH_FAST 0
#if BUILD_AS_NOMMU
@@ -485,8 +492,11 @@ struct globals {
struct function *top_func;
#endif
/* Signal and trap handling */
-// unsigned count_SIGCHLD;
-// unsigned handled_SIGCHLD;
+#if ENABLE_HUSH_FAST
+ unsigned count_SIGCHLD;
+ unsigned handled_SIGCHLD;
+ smallint last_waitpid_was_0;
+#endif
/* which signals have non-DFL handler (even with no traps set)? */
unsigned non_DFL_mask;
char **traps; /* char *traps[NSIG] */
@@ -1050,7 +1060,7 @@ static void restore_G_args(save_arg_t *sv, char **argv)
* Restore blocked signal set to one inherited by shell just prior to exec.
*
* Note: as a result, we do not use signal handlers much. The only uses
- * are to count SIGCHLDs [disabled - bug somewhere, + bloat]
+ * are to count SIGCHLDs
* and to restore tty pgrp on signal-induced exit.
*/
enum {
@@ -1067,10 +1077,13 @@ enum {
#endif
};
-//static void SIGCHLD_handler(int sig UNUSED_PARAM)
-//{
-// G.count_SIGCHLD++;
-//}
+#if ENABLE_HUSH_FAST
+static void SIGCHLD_handler(int sig UNUSED_PARAM)
+{
+ G.count_SIGCHLD++;
+//bb_error_msg("[%d] SIGCHLD_handler: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
+}
+#endif
#if ENABLE_HUSH_JOB
@@ -1158,9 +1171,12 @@ static int check_and_run_traps(int sig)
}
/* not a trap: special action */
switch (sig) {
-// case SIGCHLD:
-// G.count_SIGCHLD++;
-// break;
+#if ENABLE_HUSH_FAST
+ case SIGCHLD:
+ G.count_SIGCHLD++;
+//bb_error_msg("[%d] check_and_run_traps: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
+ break;
+#endif
case SIGINT:
/* Builtin was ^C'ed, make it look prettier: */
bb_putchar('\n');
@@ -2665,6 +2681,10 @@ static void setup_heredoc(struct redir_struct *redir)
#endif
}
/* parent */
+#if ENABLE_HUSH_FAST
+ G.count_SIGCHLD++;
+//bb_error_msg("[%d] fork in setup_heredoc: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
+#endif
enable_restore_tty_pgrp_on_exit();
#if !BB_MMU
free(to_free);
@@ -3273,9 +3293,16 @@ static int checkjobs(struct pipe* fg_pipe)
debug_printf_jobs("checkjobs %p\n", fg_pipe);
errno = 0;
-// if (G.handled_SIGCHLD == G.count_SIGCHLD)
-// /* avoid doing syscall, nothing there anyway */
-// return rcode;
+#if ENABLE_HUSH_FAST
+ if (G.handled_SIGCHLD == G.count_SIGCHLD) {
+//bb_error_msg("[%d] checkjobs: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d was 0?:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD, G.last_waitpid_was_0);
+ /* avoid doing syscall, nothing there anyway */
+ if (G.last_waitpid_was_0)
+ return 0;
+ errno = ECHILD;
+ return -1;
+ }
+#endif
attributes = WUNTRACED;
if (fg_pipe == NULL)
@@ -3294,13 +3321,20 @@ static int checkjobs(struct pipe* fg_pipe)
int i;
int dead;
-// i = G.count_SIGCHLD;
+#if ENABLE_HUSH_FAST
+ i = G.count_SIGCHLD;
+#endif
childpid = waitpid(-1, &status, attributes);
if (childpid <= 0) {
if (childpid && errno != ECHILD)
bb_perror_msg("waitpid");
-// else /* Until next SIGCHLD, waitpid's are useless */
-// G.handled_SIGCHLD = i;
+#if ENABLE_HUSH_FAST
+ else { /* Until next SIGCHLD, waitpid's are useless */
+ G.last_waitpid_was_0 = (childpid == 0);
+ G.handled_SIGCHLD = i;
+//bb_error_msg("[%d] checkjobs: waitpid returned <= 0, G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
+ }
+#endif
break;
}
dead = WIFEXITED(status) || WIFSIGNALED(status);
@@ -3696,6 +3730,10 @@ static int run_pipe(struct pipe *pi)
}
/* parent or error */
+#if ENABLE_HUSH_FAST
+ G.count_SIGCHLD++;
+//bb_error_msg("[%d] fork in run_pipe: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
+#endif
enable_restore_tty_pgrp_on_exit();
#if !BB_MMU
/* Clean up after vforked child */
@@ -4861,6 +4899,10 @@ static FILE *generate_stream_from_string(const char *s)
}
/* parent */
+#if ENABLE_HUSH_FAST
+ G.count_SIGCHLD++;
+//bb_error_msg("[%d] fork in generate_stream_from_string: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
+#endif
enable_restore_tty_pgrp_on_exit();
#if !BB_MMU
free(to_free);
@@ -5990,9 +6032,14 @@ static void block_signals(int second_time)
second_time ? NULL : &G.inherited_set);
/* POSIX allows shell to re-enable SIGCHLD
* even if it was SIG_IGN on entry */
-// G.count_SIGCHLD++; /* ensure it is != G.handled_SIGCHLD */
+#if ENABLE_HUSH_FAST
+ G.count_SIGCHLD++; /* ensure it is != G.handled_SIGCHLD */
+ if (!second_time)
+ signal(SIGCHLD, SIGCHLD_handler);
+#else
if (!second_time)
- signal(SIGCHLD, SIG_DFL); // SIGCHLD_handler);
+ signal(SIGCHLD, SIG_DFL);
+#endif
}
#if ENABLE_HUSH_JOB