fix signals

git-svn-id: http://ltt.polymtl.ca/svn@2386 04897980-b3bd-0310-b5e0-8ef037075253

diff --git a/ltt-usertrace/ltt/ltt-usertrace-fast.h b/ltt-usertrace/ltt/ltt-usertrace-fast.h
index 5bcec27db93e91feabbaee6a11ededa1a9a24d38..4656965de5193dc5903d3f75473425fa9dca19cd 100644 (file)
--- a/ltt-usertrace/ltt/ltt-usertrace-fast.h
+++ b/ltt-usertrace/ltt/ltt-usertrace-fast.h
@@ -367,7 +367,6 @@ static inline void * __attribute__((no_instrument_function)) ltt_reserve_slot(
        int commit_count, reserve_count;
        int ret;
        sigset_t oldset, set;
-       int signals_disabled = 0;
 
        do {
                offset_old = atomic_read(&ltt_buf->offset);
@@ -417,16 +416,28 @@ static inline void * __attribute__((no_instrument_function)) ltt_reserve_slot(
                                {
                                        /* sem_wait is not signal safe. Disable signals around it.
                                         * Signals are kept disabled to make sure we win the cmpxchg. */
-
                                        /* Disable signals */
-                                       if(!signals_disabled) {
-                                               ret = sigfillset(&set);
-                                               if(ret) perror("LTT Error in sigfillset\n"); 
-               
-                                               ret = pthread_sigmask(SIG_BLOCK, &set, &oldset);
+                                       ret = sigfillset(&set);
+                                       if(ret) perror("LTT Error in sigfillset\n"); 
+       
+                                       ret = pthread_sigmask(SIG_BLOCK, &set, &oldset);
+                                       if(ret) perror("LTT Error in pthread_sigmask\n");
+
+                                       /* We detect if a signal came between
+                                        * the offset read and signal disabling:
+                                        * if it is the case, then we restart
+                                        * the loop after reenabling signals. It
+                                        * means that it's a signal that has
+                                        * won the buffer switch.*/
+                                       if(offset_old != atomic_read(&ltt_buf->offset)) {
+                                               ret = pthread_sigmask(SIG_SETMASK, &oldset, NULL);
                                                if(ret) perror("LTT Error in pthread_sigmask\n");
-                                               signals_disabled = 1;
+                                               continue;
                                        }
+                                       /* If the offset is still the same, then
+                                        * we can safely proceed to do the
+                                        * buffer switch without being
+                                        * interrupted by a signal. */
                                        sem_wait(&ltt_buf->writer_sem);
 
                                }
@@ -550,7 +561,7 @@ static inline void * __attribute__((no_instrument_function)) ltt_reserve_slot(
                 * sem_wait does in fact win the cmpxchg for the offset. We only call
                 * these system calls on buffer boundaries because of their performance
                 * cost. */
-               if(signals_disabled) {
+               if(reserve_commit_diff == 0) {
                        ret = pthread_sigmask(SIG_SETMASK, &oldset, NULL);
                        if(ret) perror("LTT Error in pthread_sigmask\n");
                }