[pulseaudio-discuss] [PATCH] mainloop: Map POLLNVAL to PA_IO_EVENT_ERROR.

[Tanu Kaskinen]

I don't see any reason why POLLNVAL should be ignored like
it is now without this patch. PA_IO_EVENT_ERROR seems to be
the best choice for reporting the IO event type, because
POLLNVAL is an error condition and adding a new IO event
type just for POLLNVAL probably wouldn't add any value.

This patch seems to have made one hard to reproduce bug
impossible to reproduce. The problem was that a certain
client application (involving GStreamer) occasionally
started to consume 100% of CPU. Based on some stack traces
it was speculated that the threaded mainloop of libpulse
was spinning on POLLNVAL, because some user of the mainloop
(maybe GStreamer) kept the IO event active when the IO
event was triggered with zero flags. But that's just
speculation - there's no direct evidence of POLLNVAL being
triggered at all, only that with this patch the application
has been behaving nicely so far.
---
 src/pulse/mainloop.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/src/pulse/mainloop.c b/src/pulse/mainloop.c
index 5c0345e..a27cc55 100644
--- a/src/pulse/mainloop.c
+++ b/src/pulse/mainloop.c
@@ -144,6 +144,7 @@ static pa_io_event_flags_t map_flags_from_libc(short flags) {
         (flags & POLLIN ? PA_IO_EVENT_INPUT : 0) |
         (flags & POLLOUT ? PA_IO_EVENT_OUTPUT : 0) |
         (flags & POLLERR ? PA_IO_EVENT_ERROR : 0) |
+        (flags & POLLNVAL ? PA_IO_EVENT_ERROR : 0) |
         (flags & POLLHUP ? PA_IO_EVENT_HANGUP : 0);
 }
 
-- 
1.7.8