mainloop: avoid race-y double wakeup status

Having an extra variable that tracks the wakeup status introduces a
race where the variable is set but the data has yet to propagate from
the write end of the pipe to the read end. When this happens the
system goes into a tight loop as select() always returns immediately.

1 files changed, 2 insertions, 7 deletions

diff --git a/src/pulse/mainloop.c b/src/pulse/mainloop.c
index 66a147566..5ef58ffb3 100644
--- a/src/pulse/mainloop.c
+++ b/src/pulse/mainloop.c
@@ -114,7 +114,6 @@ struct pa_mainloop {
     int retval;
     bool quit:1;
 
-    pa_atomic_t wakeup_requested;
     int wakeup_pipe[2];
     int wakeup_pipe_type;
 
@@ -774,8 +773,6 @@ void pa_mainloop_wakeup(pa_mainloop *m) {
     if (pa_write(m->wakeup_pipe[1], &c, sizeof(c), &m->wakeup_pipe_type) < 0)
         /* Not much options for recovering from the error. Let's at least log something. */
         pa_log("pa_write() failed while trying to wake up the mainloop: %s", pa_cstrerror(errno));
-
-    pa_atomic_store(&m->wakeup_requested, true);
 }
 
 static void clear_wakeup(pa_mainloop *m) {
@@ -783,10 +780,8 @@ static void clear_wakeup(pa_mainloop *m) {
 
     pa_assert(m);
 
-    if (pa_atomic_cmpxchg(&m->wakeup_requested, true, false)) {
-        while (pa_read(m->wakeup_pipe[0], &c, sizeof(c), &m->wakeup_pipe_type) == sizeof(c))
-            ;
-    }
+    while (pa_read(m->wakeup_pipe[0], &c, sizeof(c), &m->wakeup_pipe_type) == sizeof(c))
+        ;
 }
 
 int pa_mainloop_prepare(pa_mainloop *m, int timeout) {