Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760164AbaLLGRx (ORCPT ); Fri, 12 Dec 2014 01:17:53 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51900 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760073AbaLLGRU (ORCPT ); Fri, 12 Dec 2014 01:17:20 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Takashi Iwai" Date: Fri, 12 Dec 2014 06:14:25 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 060/164] ALSA: emu10k1: Fix deadlock in synth voice lookup In-Reply-To: X-SA-Exim-Connect-IP: 2001:470:1f08:1539:c97:8151:cc89:c28d X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.65-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit 95926035b187cc9fee6fb61385b7da9c28123f74 upstream. The emu10k1 voice allocator takes voice_lock spinlock. When there is no empty stream available, it tries to release a voice used by synth, and calls get_synth_voice. The callback function, snd_emu10k1_synth_get_voice(), however, also takes the voice_lock, thus it deadlocks. The fix is simply removing the voice_lock holds in snd_emu10k1_synth_get_voice(), as this is always called in the spinlock context. Reported-and-tested-by: Arthur Marsh Signed-off-by: Takashi Iwai Signed-off-by: Ben Hutchings --- sound/pci/emu10k1/emu10k1_callback.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) --- a/sound/pci/emu10k1/emu10k1_callback.c +++ b/sound/pci/emu10k1/emu10k1_callback.c @@ -85,6 +85,8 @@ snd_emu10k1_ops_setup(struct snd_emux *e * get more voice for pcm * * terminate most inactive voice and give it as a pcm voice. + * + * voice_lock is already held. */ int snd_emu10k1_synth_get_voice(struct snd_emu10k1 *hw) @@ -92,12 +94,10 @@ snd_emu10k1_synth_get_voice(struct snd_e struct snd_emux *emu; struct snd_emux_voice *vp; struct best_voice best[V_END]; - unsigned long flags; int i; emu = hw->synth; - spin_lock_irqsave(&emu->voice_lock, flags); lookup_voices(emu, hw, best, 1); /* no OFF voices */ for (i = 0; i < V_END; i++) { if (best[i].voice >= 0) { @@ -113,11 +113,9 @@ snd_emu10k1_synth_get_voice(struct snd_e vp->emu->num_voices--; vp->ch = -1; vp->state = SNDRV_EMUX_ST_OFF; - spin_unlock_irqrestore(&emu->voice_lock, flags); return ch; } } - spin_unlock_irqrestore(&emu->voice_lock, flags); /* not found */ return -ENOMEM; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/