2004-07-14 Paul Jakma <paul@dishone.st>

        * sigevent.c: (quagga_signal_handler) add a global caught flag, set
          the flags to a constant rather increment to be kinder.
          (quagga_sigevent_process) new function, to do core of what
          quagga_signal_timer did. dont block signals at all as sig->caught
          is volatile sig_atomic_t and should be safe to access from signal
          and normal contexts. The signal blocking is unneeded paranoia, but
          is left intact under an ifdef, should some platform require it.
          Check global caught flag before iterating through array.
          (quagga_signal_timer) nearly everything moved to
          quagga_sigevent_process. Left in under ifdef, in case some
          platform could use a regular timer check for signals.
        * sigevent.h: quagga_sigevent_process declaration.
        * thread.c: (thread_fetch) check for signals at beginning of
          scheduler loop, check for signals if select returns EINTR.

1 files changed, 54 insertions, 29 deletions

diff --git a/lib/sigevent.c b/lib/sigevent.c
index 6a2fd80c..937180c9 100644
--- a/lib/sigevent.c
+++ b/lib/sigevent.c
@@ -23,15 +23,16 @@
 #include <sigevent.h>
 #include <log.h>
 
+/* master signals descriptor struct */
 struct quagga_sigevent_master_t
 {
-  struct thread_master *tm;
   struct thread *t;
 
-  struct quagga_signal_t *signals;
+  struct quagga_signal_t *signals; 
   int sigc;
- 
-} sigmaster; 
+  
+  volatile sig_atomic_t caught;
+} sigmaster;
 
 /* Generic signal handler 
  * Schedules signal event thread
@@ -47,20 +48,22 @@ quagga_signal_handler (int signo)
       sig = &(sigmaster.signals[i]);
       
       if (sig->signal == signo)
-        sig->caught++;
+        sig->caught = 1;
     }
+  
+  sigmaster.caught = 1;
 } 
 
+/* check if signals have been caught and run appropriate handlers */
 int
-quagga_signal_timer (struct thread *t)
+quagga_sigevent_process (void)
 {
-  sigset_t newmask, oldmask;
-  struct quagga_sigevent_master_t *sigm;
   struct quagga_signal_t *sig;
   int i;
+#ifdef SIGEVENT_BLOCK_SIGNALS
+  /* shouldnt need to block signals, but potentially may be needed */
+  sigset_t newmask, oldmask;
 
-  sigm = THREAD_ARG (t);
-  
   /*
    * Block most signals, but be careful not to defer SIGTRAP because
    * doing so breaks gdb, at least on NetBSD 2.0.  Avoid asking to
@@ -69,34 +72,57 @@ quagga_signal_timer (struct thread *t)
   sigfillset (&newmask);
   sigdelset (&newmask, SIGTRAP);
   sigdelset (&newmask, SIGKILL);
-
+   
   if ( (sigprocmask (SIG_BLOCK, &newmask, &oldmask)) < 0)
     {
       zlog_err ("quagga_signal_timer: couldnt block signals!");
-		  sigm->t = thread_add_timer (sigm->tm, quagga_signal_timer, 
-		                              &sigmaster, QUAGGA_SIGNAL_TIMER_INTERVAL);    
       return -1;
     }
-  
-  for (i = 0; i < sigm->sigc; i++)
+#endif /* SIGEVENT_BLOCK_SIGNALS */
+
+  if (sigmaster.caught > 0)
     {
-      sig = &(sigm->signals[i]);
-      if (sig->caught > 0)
+      sigmaster.caught = 0;
+      /* must not read or set sigmaster.caught after here,
+       * race condition with per-sig caught flags if one does
+       */
+      
+      for (i = 0; i < sigmaster.sigc; i++)
         {
-          sig->caught = 0;
-          sig->handler();
+          sig = &(sigmaster.signals[i]);
+
+          if (sig->caught > 0)
+            {
+              sig->caught = 0;
+              sig->handler ();
+            }
         }
     }
-  
-  sigm->t = thread_add_timer (sigm->tm, quagga_signal_timer, &sigmaster, 
-                                           QUAGGA_SIGNAL_TIMER_INTERVAL);
 
+#ifdef SIGEVENT_BLOCK_SIGNALS
   if ( sigprocmask (SIG_UNBLOCK, &oldmask, NULL) < 0 );
     return -1;
-  
+#endif /* SIGEVENT_BLOCK_SIGNALS */
+
   return 0;
 }
 
+#ifdef SIGEVENT_SCHEDULE_THREAD
+/* timer thread to check signals. Shouldnt be needed */
+int
+quagga_signal_timer (struct thread *t)
+{
+  struct quagga_sigevent_master_t *sigm;
+  struct quagga_signal_t *sig;
+  int i;
+
+  sigm = THREAD_ARG (t);
+  sigm->t = thread_add_timer (sigm->t->master, quagga_signal_timer, &sigmaster,
+                              QUAGGA_SIGNAL_TIMER_INTERVAL);
+  return quagga_sigevent_process ();
+}
+#endif /* SIGEVENT_SCHEDULE_THREAD */
+
 /* Initialization of signal handles. */
 /* Signale wrapper. */
 int
@@ -127,8 +153,8 @@ signal_set (int signo)
 }
 
 void 
-signal_init (struct thread_master *m, 
-             int sigc, struct quagga_signal_t signals[])
+signal_init (struct thread_master *m, int sigc, 
+             struct quagga_signal_t signals[])
 {
 
   int i = 0;
@@ -144,11 +170,10 @@ signal_init (struct thread_master *m,
 
   sigmaster.sigc = sigc;
   sigmaster.signals = signals;
-  sigmaster.tm = m;
-  
+
+#ifdef SIGEVENT_SCHEDULE_THREAD  
   sigmaster.t = 
     thread_add_timer (m, quagga_signal_timer, &sigmaster, 
                       QUAGGA_SIGNAL_TIMER_INTERVAL);
-
+#endif /* SIGEVENT_SCHEDULE_THREAD */
 }
-