From 945da099ae631edae12ddbe7b590b0bf0eb8c56c Mon Sep 17 00:00:00 2001 From: Cameron Gutman Date: Sat, 22 Feb 2025 12:33:19 -0600 Subject: [PATCH] pipewire: Fix possible deadlock when opening a device If the pipewire thread invokes output_callback() while we're still waiting inside PIPEWIRE_OpenDevice(), we will deadlock. The pipewire thread owns the loop lock and is blocked on the audio device lock, which cannot be released because pw_thread_loop_wait() needs to reacquire the loop lock before it can return and allow PIPEWIRE_OpenDevice() to complete and release the device lock. --- src/audio/pipewire/SDL_pipewire.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/src/audio/pipewire/SDL_pipewire.c b/src/audio/pipewire/SDL_pipewire.c index 40324f4f18..e3f9439f73 100644 --- a/src/audio/pipewire/SDL_pipewire.c +++ b/src/audio/pipewire/SDL_pipewire.c @@ -44,7 +44,9 @@ enum PW_READY_FLAGS { PW_READY_FLAG_BUFFER_ADDED = 0x1, PW_READY_FLAG_STREAM_READY = 0x2, - PW_READY_FLAG_ALL_BITS = 0x3 + PW_READY_FLAG_ALL_PREOPEN_BITS = 0x3, + PW_READY_FLAG_OPEN_COMPLETE = 0x4, + PW_READY_FLAG_ALL_BITS = 0x7 }; #define PW_ID_TO_HANDLE(x) (void *)((uintptr_t)x) @@ -1215,12 +1217,13 @@ static bool PIPEWIRE_OpenDevice(SDL_AudioDevice *device) return SDL_SetError("Pipewire: Failed to start stream loop"); } - // Wait until all init flags are set or the stream has failed. + // Wait until all pre-open init flags are set or the stream has failed. PIPEWIRE_pw_thread_loop_lock(priv->loop); - while (priv->stream_init_status != PW_READY_FLAG_ALL_BITS && + while (priv->stream_init_status != PW_READY_FLAG_ALL_PREOPEN_BITS && PIPEWIRE_pw_stream_get_state(priv->stream, NULL) != PW_STREAM_STATE_ERROR) { PIPEWIRE_pw_thread_loop_wait(priv->loop); } + priv->stream_init_status |= PW_READY_FLAG_OPEN_COMPLETE; PIPEWIRE_pw_thread_loop_unlock(priv->loop); if (PIPEWIRE_pw_stream_get_state(priv->stream, &error) == PW_STREAM_STATE_ERROR) {