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.

4 files changed, 100 insertions, 46 deletions

diff --git a/lib/ChangeLog b/lib/ChangeLog
index 108a2023..b3d452e0 100644
--- a/lib/ChangeLog
+++ b/lib/ChangeLog
@@ -1,3 +1,20 @@
+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.
+	 
 2004-07-13  Greg Troxel  <gdt@poblano.ir.bbn.com>
 
 	* sigevent.c: Don't block SIGTRAP and SIGKILL.  Blocking SIGTRAP
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 */
 }
-
diff --git a/lib/sigevent.h b/lib/sigevent.h
index 6296736a..20012aff 100644
--- a/lib/sigevent.h
+++ b/lib/sigevent.h
@@ -23,6 +23,7 @@
 
 #ifndef _QUAGGA_SIGNAL_H
 #define _QUAGGA_SIGNAL_H
+
 #include <thread.h>
 
 #define QUAGGA_SIGNAL_TIMER_INTERVAL 2L
@@ -46,4 +47,7 @@ struct quagga_signal_t
 void signal_init (struct thread_master *m, int sigc, 
                          struct quagga_signal_t *signals);
 
+/* check whether there are signals to handle, process any found */
+int quagga_sigevent_process (void);
+
 #endif /* _QUAGGA_SIGNAL_H */
diff --git a/lib/thread.c b/lib/thread.c
index 93809f2f..2e953c55 100644
--- a/lib/thread.c
+++ b/lib/thread.c
@@ -28,6 +28,7 @@
 #include "log.h"
 #include "hash.h"
 #include "command.h"
+#include "sigevent.h"
 
 static struct hash *cpu_record = NULL;
 
@@ -748,23 +749,26 @@ thread_fetch (struct thread_master *m, struct thread *fetch)
 
   while (1)
     {
-      /* Normal event is the highest priority.  */
+      /* Signals are highest priority */
+      quagga_sigevent_process ();
+       
+      /* Normal event are the next highest priority.  */
       if ((thread = thread_trim_head (&m->event)) != NULL)
-	return thread_run (m, thread, fetch);
+        return thread_run (m, thread, fetch);
 
       /* Execute timer.  */
       gettimeofday (&timer_now, NULL);
 
       for (thread = m->timer.head; thread; thread = thread->next)
-	if (timeval_cmp (timer_now, thread->u.sands) >= 0)
-	  {
-	    thread_list_delete (&m->timer, thread);
-	    return thread_run (m, thread, fetch);
-	  }
+        if (timeval_cmp (timer_now, thread->u.sands) >= 0)
+          {
+            thread_list_delete (&m->timer, thread);
+            return thread_run (m, thread, fetch);
+          }
 
       /* If there are any ready threads, process top of them.  */
       if ((thread = thread_trim_head (&m->ready)) != NULL)
-	return thread_run (m, thread, fetch);
+        return thread_run (m, thread, fetch);
 
       /* Structure copy.  */
       readfd = m->readfd;
@@ -777,16 +781,20 @@ thread_fetch (struct thread_master *m, struct thread *fetch)
       num = select (FD_SETSIZE, &readfd, &writefd, &exceptfd, timer_wait);
 
       if (num == 0)
-	continue;
+        continue;
 
       if (num < 0)
-	{
-	  if (errno == EINTR)
-	    continue;
-
-	  zlog_warn ("select() error: %s", strerror (errno));
-	  return NULL;
-	}
+        {
+          if (errno == EINTR)
+            {
+              /* signal received */
+              quagga_sigevent_process ();
+              continue;
+            }
+
+          zlog_warn ("select() error: %s", strerror (errno));
+            return NULL;
+        }
 
       /* Normal priority read thead. */
       ready = thread_process_fd (m, &m->read, &readfd, &m->readfd);
@@ -795,7 +803,7 @@ thread_fetch (struct thread_master *m, struct thread *fetch)
       ready = thread_process_fd (m, &m->write, &writefd, &m->writefd);
 
       if ((thread = thread_trim_head (&m->ready)) != NULL)
-	return thread_run (m, thread, fetch);
+        return thread_run (m, thread, fetch);
     }
 }