Fix: ignore SIGPIPE

Issuing fprintf() to stderr (thus write() to the standard error file
descriptor) within the SIGPIPE signal handler is bad: it can trigger
SIGPIPE repeatedly if the listening end has closed its end of the pipe.

Set the SIGPIPE action to SIG_IGN in relayd, sessiond, and consumerd.

This was affecting sessiond and relayd. The consumerd did not print
anything to stderr.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/bin/lttng-consumerd/lttng-consumerd.c b/src/bin/lttng-consumerd/lttng-consumerd.c
index c22cdd0fabeab9a2e7855e611ad3e2795e8c30cf..d4c42be67b7a396cd2d8c4a7badc47c43a1cddee 100644 (file)
--- a/src/bin/lttng-consumerd/lttng-consumerd.c
+++ b/src/bin/lttng-consumerd/lttng-consumerd.c
@@ -101,14 +101,6 @@ static void sighandler(int sig)
                return;
        }
 
-       /*
-        * Ignore SIGPIPE because it should not stop the consumer whenever a
-        * SIGPIPE is caught through a FD operation.
-        */
-       if (sig == SIGPIPE) {
-               return;
-       }
-
        if (ctx) {
                lttng_consumer_should_exit(ctx);
        }
@@ -129,9 +121,10 @@ static int set_signal_handler(void)
                return ret;
        }
 
-       sa.sa_handler = sighandler;
        sa.sa_mask = sigset;
        sa.sa_flags = 0;
+
+       sa.sa_handler = sighandler;
        if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
                PERROR("sigaction");
                return ret;
@@ -142,6 +135,7 @@ static int set_signal_handler(void)
                return ret;
        }
 
+       sa.sa_handler = SIG_IGN;
        if ((ret = sigaction(SIGPIPE, &sa, NULL)) < 0) {
                PERROR("sigaction");
                return ret;

diff --git a/src/bin/lttng-relayd/main.c b/src/bin/lttng-relayd/main.c
index 1ea2d2c08e5d96b0a894b43bbf33c7a48c3e4b41..9a0c7c2a0dfe01b72d28c3247e349688779c5ad7 100644 (file)
--- a/src/bin/lttng-relayd/main.c
+++ b/src/bin/lttng-relayd/main.c
@@ -598,9 +598,6 @@ int lttng_relay_stop_threads(void)
 static void sighandler(int sig)
 {
        switch (sig) {
-       case SIGPIPE:
-               DBG("SIGPIPE caught");
-               return;
        case SIGINT:
                DBG("SIGINT caught");
                if (lttng_relay_stop_threads()) {
@@ -636,9 +633,10 @@ static int set_signal_handler(void)
                return ret;
        }
 
-       sa.sa_handler = sighandler;
        sa.sa_mask = sigset;
        sa.sa_flags = 0;
+
+       sa.sa_handler = sighandler;
        if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
                PERROR("sigaction");
                return ret;
@@ -649,12 +647,13 @@ static int set_signal_handler(void)
                return ret;
        }
 
-       if ((ret = sigaction(SIGPIPE, &sa, NULL)) < 0) {
+       if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
                PERROR("sigaction");
                return ret;
        }
 
-       if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
+       sa.sa_handler = SIG_IGN;
+       if ((ret = sigaction(SIGPIPE, &sa, NULL)) < 0) {
                PERROR("sigaction");
                return ret;
        }

diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
index d3ee890aece3de108b9bc80bbb8ff4d6252220cb..bd27b2fc451d847be4d1bbaf27457a62337d127d 100644 (file)
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -5325,9 +5325,6 @@ error:
 static void sighandler(int sig)
 {
        switch (sig) {
-       case SIGPIPE:
-               DBG("SIGPIPE caught");
-               return;
        case SIGINT:
                DBG("SIGINT caught");
                stop_threads();
@@ -5359,9 +5356,10 @@ static int set_signal_handler(void)
                return ret;
        }
 
-       sa.sa_handler = sighandler;
        sa.sa_mask = sigset;
        sa.sa_flags = 0;
+
+       sa.sa_handler = sighandler;
        if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
                PERROR("sigaction");
                return ret;
@@ -5372,12 +5370,13 @@ static int set_signal_handler(void)
                return ret;
        }
 
-       if ((ret = sigaction(SIGPIPE, &sa, NULL)) < 0) {
+       if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
                PERROR("sigaction");
                return ret;
        }
 
-       if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
+       sa.sa_handler = SIG_IGN;
+       if ((ret = sigaction(SIGPIPE, &sa, NULL)) < 0) {
                PERROR("sigaction");
                return ret;
        }