r20941: avoid races in the block/unblock code

diff --git a/source/lib/events/events_signal.c b/source/lib/events/events_signal.c
index 28702cecc93af9d646996db9e3fb931818f742fa..21542d863b17acf3c65b7b5396ce97622a99a625 100644 (file)
--- a/source/lib/events/events_signal.c
+++ b/source/lib/events/events_signal.c
@@ -54,6 +54,7 @@ static struct {
 #ifdef SA_SIGINFO
        /* with SA_SIGINFO we get quite a lot of info per signal */
        siginfo_t *sig_info[NUM_SIGNALS];
+       struct sigcounter sig_blocked[NUM_SIGNALS];
 #endif
 } sig_state;
 
@@ -99,6 +100,7 @@ static void signal_handler_info(int signum, siginfo_t *info, void *uctx)
                sigemptyset(&set);
                sigaddset(&set, signum);
                sigprocmask(SIG_BLOCK, &set, NULL);
+               SIG_INCREMENT(sig_state.sig_blocked[signum]);
        }
 }
 #endif
@@ -226,7 +228,8 @@ int common_event_check_signal(struct event_context *ev)
        
        for (i=0;i<NUM_SIGNALS+1;i++) {
                struct signal_event *se, *next;
-               uint32_t count = sig_count(sig_state.signal_count[i]);
+               struct sigcounter counter = sig_state.signal_count[i];
+               uint32_t count = sig_count(counter);
 
                if (count == 0) {
                        continue;
@@ -237,16 +240,21 @@ int common_event_check_signal(struct event_context *ev)
                        if (se->sa_flags & SA_SIGINFO) {
                                int j;
                                for (j=0;j<count;j++) {
+                                       /* note the use of the sig_info array as a
+                                          ring buffer */
+                                       int ofs = (counter.count + j) % SA_INFO_QUEUE_COUNT;
                                        se->handler(ev, se, i, 1, 
-                                                   (void*)&sig_state.sig_info[i][j], 
+                                                   (void*)&sig_state.sig_info[i][ofs], 
                                                    se->private_data);
                                }
-                               if (count == SA_INFO_QUEUE_COUNT) {
+                               if (SIG_PENDING(sig_state.sig_blocked[i])) {
                                        /* we'd filled the queue, unblock the
                                           signal now */
                                        sigset_t set;
                                        sigemptyset(&set);
                                        sigaddset(&set, i);
+                                       SIG_SEEN(sig_state.sig_blocked[i], 
+                                                sig_count(sig_state.sig_blocked[i]));
                                        sigprocmask(SIG_UNBLOCK, &set, NULL);
                                }
                                if (se->sa_flags & SA_RESETHAND) {