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 00660fcd6a7d401aa3096236026eabd1900d5f64..079bd60240ef2ac864a51e05c755423c78b9ddf0 100644 (file)
--- a/src/bin/lttng-consumerd/lttng-consumerd.c
+++ b/src/bin/lttng-consumerd/lttng-consumerd.c
@@ -99,14 +99,6 @@ 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);
        }
@@ -127,9 +119,10 @@ 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;
@@ -140,6 +133,7 @@ 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 6ad6566254260a8af071e2c2ce26348fd148486c..2a2c998bb02ac6a0cabe425ca92e3c7bac7b214f 100644 (file)
--- a/src/bin/lttng-relayd/main.c
+++ b/src/bin/lttng-relayd/main.c
@@ -582,9 +582,6 @@ 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()) {
@@ -620,9 +617,10 @@ 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;
@@ -633,12 +631,13 @@ 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 fb659b7e02d31a21168dfda4c15332fb8486514f..e4aaa9928f31a0a5a488277d7fee9c645c05d6e4 100644 (file)
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -5416,9 +5416,6 @@ error:
 static void sighandler(int sig)
 {
        switch (sig) {
-       case SIGPIPE:
-               DBG("SIGPIPE caught");
-               return;
        case SIGINT:
                DBG("SIGINT caught");
                stop_threads();
@@ -5450,9 +5447,10 @@ 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;
@@ -5463,12 +5461,13 @@ 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;
        }