X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=libust%2Ftracectl.c;h=2f9215e65b29adc0df6095ce72c206425304c559;hb=1eba9d6b2081a1e75e7f711ac02023dde773bef1;hp=39756a55fec0e72602479593fce153408fc950d5;hpb=c95b244d5c6c391ea6a5deb400ac57ba38e837ba;p=ust.git

diff --git a/libust/tracectl.c b/libust/tracectl.c
index 39756a5..2f9215e 100644
--- a/libust/tracectl.c
+++ b/libust/tracectl.c
@@ -15,10 +15,16 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  */
 
+/* This file contains the implementation of the UST listener thread, which
+ * receives trace control commands. It also coordinates the initialization of
+ * libust.
+ */
+
 #define _GNU_SOURCE
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>
+#include <pthread.h>
 #include <signal.h>
 #include <sys/types.h>
 #include <sys/socket.h>
@@ -48,6 +54,8 @@
  */
 s64 pidunique = -1LL;
 
+extern struct chan_info_struct chan_infos[];
+
 struct list_head blocked_consumers = LIST_HEAD_INIT(blocked_consumers);
 
 static struct ustcomm_app ustcomm_app;
@@ -456,18 +464,18 @@ 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 = 2147483648u; /* FIX max 2^31 */
-
-    if (x < 2)
-        return 2;
+/* Return the power of two which is equal or higher to v */
 
-    while (power2 < x && power2 < hardcoded)
-        power2 *= 2;
-
-    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)
@@ -491,9 +499,10 @@ 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);
@@ -1030,17 +1039,38 @@ 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;
 }
 
@@ -1091,6 +1121,11 @@ static void __attribute__((constructor)) init()
 {
 	int result;
 	char* autoprobe_val = NULL;
+	char* subbuffer_size_val = NULL;
+	char* subbuffer_count_val = NULL;
+	unsigned int subbuffer_size;
+	unsigned int subbuffer_count;
+	unsigned int power;
 
 	/* Assign the pidunique, to be able to differentiate the processes with same
 	 * pid, (before and after an exec).
@@ -1174,6 +1209,23 @@ static void __attribute__((constructor)) init()
 		}
 	}
 
+	subbuffer_size_val = getenv("UST_SUBBUF_SIZE");
+	if(subbuffer_size_val) {
+		sscanf(subbuffer_size_val, "%u", &subbuffer_size);
+		power = pow2_higher_or_eq(subbuffer_size);
+		if(power != subbuffer_size)
+			WARN("using the next power of two for buffer size = %u\n", power);
+		chan_infos[LTT_CHANNEL_UST].def_subbufsize = power;
+	}
+
+	subbuffer_count_val = getenv("UST_SUBBUF_NUM");
+	if(subbuffer_count_val) {
+		sscanf(subbuffer_count_val, "%u", &subbuffer_count);
+		if(subbuffer_count < 2)
+			subbuffer_count = 2;
+		chan_infos[LTT_CHANNEL_UST].def_subbufcount = subbuffer_count;
+	}
+
 	if(getenv("UST_TRACE")) {
 		char trace_name[] = "auto";
 		char trace_type[] = "ustrelay";
@@ -1240,7 +1292,6 @@ static void __attribute__((constructor)) init()
 		inform_consumer_daemon(trace_name);
 	}
 
-
 	return;
 
 	/* should decrementally destroy stuff if error */