epoll/poll compat: expose interruptible API

[lttng-tools.git] / src / common / compat / compat-epoll.c

diff --git a/src/common/compat/compat-epoll.c b/src/common/compat/compat-epoll.c
index dbaf6823364eb5e4444ba536ac0291300a527a0a..794041726ad51226e331c511526c4ff95de128d5 100644 (file)
--- a/src/common/compat/compat-epoll.c
+++ b/src/common/compat/compat-epoll.c
@@ -23,6 +23,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <stdbool.h>
 
 #include <common/error.h>
 #include <common/defaults.h>
@@ -241,7 +242,8 @@ error:
 /*
  * Wait on epoll set. This is a blocking call of timeout value.
  */
-int compat_epoll_wait(struct lttng_poll_event *events, int timeout)
+int compat_epoll_wait(struct lttng_poll_event *events, int timeout,
+               bool interruptible)
 {
        int ret;
        uint32_t new_size;
@@ -273,10 +275,11 @@ int compat_epoll_wait(struct lttng_poll_event *events, int timeout)
 
        do {
                ret = epoll_wait(events->epfd, events->events, events->nb_fd, timeout);
-       } while (ret == -1 && errno == EINTR);
+       } while (!interruptible && ret == -1 && errno == EINTR);
        if (ret < 0) {
-               /* At this point, every error is fatal */
-               PERROR("epoll_wait");
+               if (errno != EINTR) {
+                       PERROR("epoll_wait");
+               }
                goto error;
        }
 
@@ -301,7 +304,15 @@ int compat_epoll_set_max_size(void)
 
        fd = open(COMPAT_EPOLL_PROC_PATH, O_RDONLY);
        if (fd < 0) {
-               retval = -1;
+               /*
+                * Failing on opening [1] is not an error per see. [1] was
+                * introduced in Linux 2.6.28 but epoll is available since
+                * 2.5.44. Hence, goto end and set a default value without
+                * setting an error return value.
+                *
+                * [1] /proc/sys/fs/epoll/max_user_watches
+                */
+               retval = 0;
                goto end;
        }