block all signals in listener thread

[ust.git] / libust / tracectl.c

diff --git a/libust/tracectl.c b/libust/tracectl.c
index bb03447d6fabdad5cea31cde8ec5e3bc888a35ac..7a5cf9562282ce7fe90cc3d5e4c405d3bf44b8c6 100644 (file)
--- a/libust/tracectl.c
+++ b/libust/tracectl.c
@@ -19,6 +19,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>
+#include <pthread.h>
 #include <signal.h>
 #include <sys/types.h>
 #include <sys/socket.h>
@@ -58,7 +59,7 @@ struct tracecmd { /* no padding */
 };
 
 /* volatile because shared between the listener and the main thread */
-volatile sig_atomic_t buffers_to_export = 0;
+int buffers_to_export = 0;
 
 struct trctl_msg {
        /* size: the size of all the fields except size itself */
@@ -144,17 +145,19 @@ static void inform_consumer_daemon(const char *trace_name)
        }
 
        for(i=0; i < trace->nr_channels; i++) {
-               /* iterate on all cpus */
-               for(j=0; j<trace->channels[i].n_cpus; j++) {
-                       char *buf;
-                       asprintf(&buf, "%s_%d", trace->channels[i].channel_name, j);
-                       result = ustcomm_request_consumer(pid, buf);
-                       if(result == -1) {
-                               WARN("Failed to request collection for channel %s. Is the daemon available?", trace->channels[i].channel_name);
-                               /* continue even if fail */
+               if(trace->channels[i].request_collection) {
+                       /* iterate on all cpus */
+                       for(j=0; j<trace->channels[i].n_cpus; j++) {
+                               char *buf;
+                               asprintf(&buf, "%s_%d", trace->channels[i].channel_name, j);
+                               result = ustcomm_request_consumer(pid, buf);
+                               if(result == -1) {
+                                       WARN("Failed to request collection for channel %s. Is the daemon available?", trace->channels[i].channel_name);
+                                       /* continue even if fail */
+                               }
+                               free(buf);
+                               STORE_SHARED(buffers_to_export, LOAD_SHARED(buffers_to_export)+1);
                        }
-                       free(buf);
-                       buffers_to_export++;
                }
        }
 
@@ -454,18 +457,18 @@ static int do_cmd_get_subbuf_size(const char *recvbuf, struct ustcomm_source *sr
        return retval;
 }
 
-static unsigned int poweroftwo(unsigned int x)
-{
-    unsigned int power2 = 1;
-    unsigned int hardcoded = 2147483648; /* FIX max 2^31 */
-
-    if (x < 2)
-        return 2;
-
-    while (power2 < x && power2 < hardcoded)
-        power2 *= 2;
+/* Return the power of two which is equal or higher to v */
 
-    return power2;
+static unsigned int pow2_higher_or_eq(unsigned int v)
+{
+       int hb = fls(v);
+       int hbm1 = hb-1;
+       int retval = 1<<(hb-1);
+
+       if(v-retval == 0)
+               return retval;
+       else
+               return retval<<1;
 }
 
 static int do_cmd_set_subbuf_size(const char *recvbuf, struct ustcomm_source *src)
@@ -489,9 +492,10 @@ static int do_cmd_set_subbuf_size(const char *recvbuf, struct ustcomm_source *sr
                goto end;
        }
 
-       power = poweroftwo(size);
+       power = pow2_higher_or_eq(size);
+       power = max_t(unsigned int, 2u, power);
        if (power != size)
-               WARN("using the next 2^n = %u\n", power);
+               WARN("using the next power of two for buffer size = %u\n", power);
 
        ltt_lock_traces();
        trace = _ltt_trace_find_setup(trace_name);
@@ -645,7 +649,7 @@ static int do_cmd_get_subbuffer(const char *recvbuf, struct ustcomm_source *src)
                         */
                        if(uatomic_read(&buf->consumed) == 0) {
                                DBG("decrementing buffers_to_export");
-                               buffers_to_export--;
+                               STORE_SHARED(buffers_to_export, LOAD_SHARED(buffers_to_export)-1);
                        }
 
                        break;
@@ -1028,17 +1032,38 @@ static pthread_t listener_thread;
 void create_listener(void)
 {
        int result;
+       sigset_t sig_all_blocked;
+       sigset_t orig_parent_mask;
 
        if(have_listener) {
                WARN("not creating listener because we already had one");
                return;
        }
 
+       /* A new thread created by pthread_create inherits the signal mask
+        * from the parent. To avoid any signal being received by the
+        * listener thread, we block all signals temporarily in the parent,
+        * while we create the listener thread.
+        */
+
+       sigfillset(&sig_all_blocked);
+
+       result = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_parent_mask);
+       if(result) {
+               PERROR("pthread_sigmask: %s", strerror(result));
+       }
+
        result = pthread_create(&listener_thread, NULL, listener_main, NULL);
        if(result == -1) {
                PERROR("pthread_create");
        }
 
+       /* Restore original signal mask in parent */
+       result = pthread_sigmask(SIG_SETMASK, &orig_parent_mask, NULL);
+       if(result) {
+               PERROR("pthread_sigmask: %s", strerror(result));
+       }
+
        have_listener = 1;
 }
 
@@ -1152,6 +1177,26 @@ static void __attribute__((constructor)) init()
                }
        }
 
+       if(getenv("UST_OVERWRITE")) {
+               int val = atoi(getenv("UST_OVERWRITE"));
+               if(val == 0 || val == 1) {
+                       STORE_SHARED(ust_channels_overwrite_by_default, val);
+               }
+               else {
+                       WARN("invalid value for UST_OVERWRITE");
+               }
+       }
+
+       if(getenv("UST_AUTOCOLLECT")) {
+               int val = atoi(getenv("UST_AUTOCOLLECT"));
+               if(val == 0 || val == 1) {
+                       STORE_SHARED(ust_channels_request_collection_by_default, val);
+               }
+               else {
+                       WARN("invalid value for UST_AUTOCOLLECT");
+               }
+       }
+
        if(getenv("UST_TRACE")) {
                char trace_name[] = "auto";
                char trace_type[] = "ustrelay";
@@ -1322,10 +1367,10 @@ static void stop_listener()
 
 static void __attribute__((destructor)) keepalive()
 {
-       if(trace_recording() && buffers_to_export) {
+       if(trace_recording() && LOAD_SHARED(buffers_to_export)) {
                int total = 0;
                DBG("Keeping process alive for consumer daemon...");
-               while(buffers_to_export) {
+               while(LOAD_SHARED(buffers_to_export)) {
                        const int interv = 200000;
                        restarting_usleep(interv);
                        total += interv;
@@ -1394,7 +1439,7 @@ static void ust_fork(void)
        /* free app, keeping socket file */
        ustcomm_fini_app(&ustcomm_app, 1);
 
-       buffers_to_export = 0;
+       STORE_SHARED(buffers_to_export, 0);
        have_listener = 0;
        init_socket();
        create_listener();