From c6482dde1c2811afba289b2344268f850595f350 Mon Sep 17 00:00:00 2001 From: Arjan van de Ven Date: Tue, 4 Jul 2006 03:07:22 -0700 Subject: [PATCH] [PATCH] fix AB-BA deadlock inversion at cs46xx_dsp_remove_scb There is a code sequence where the locking is substream->self_group.lock -> ins->scbs[index].lock substream->self_group.lock is interrupt safe, and taken from irq context as well (trace is snipped for brevity) so what can happen is cpu 0 cpu 1 user context user context take ins->scbs[index].lock without disabling interrupts get substream->self_group.lock (irqsafe) try to get ins->scbs[index].lock (spins) interrupt happens try to get substream->self_group.lock (spins) which is an obvious AB-BA deadlock fix is to just take the lock with _irqsafe Signed-off-by: Arjan van de Ven Cc: Jaroslav Kysela Acked-by: Takashi Iwai Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- sound/pci/cs46xx/dsp_spos_scb_lib.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/sound/pci/cs46xx/dsp_spos_scb_lib.c b/sound/pci/cs46xx/dsp_spos_scb_lib.c index 3844d18af19c..232b337852ff 100644 --- a/sound/pci/cs46xx/dsp_spos_scb_lib.c +++ b/sound/pci/cs46xx/dsp_spos_scb_lib.c @@ -180,6 +180,7 @@ static void _dsp_clear_sample_buffer (struct snd_cs46xx *chip, u32 sample_buffer void cs46xx_dsp_remove_scb (struct snd_cs46xx *chip, struct dsp_scb_descriptor * scb) { struct dsp_spos_instance * ins = chip->dsp_spos_instance; + unsigned long flags; /* check integrety */ snd_assert ( (scb->index >= 0 && @@ -194,9 +195,9 @@ void cs46xx_dsp_remove_scb (struct snd_cs46xx *chip, struct dsp_scb_descriptor * goto _end); #endif - spin_lock(&scb->lock); + spin_lock_irqsave(&scb->lock, flags); _dsp_unlink_scb (chip,scb); - spin_unlock(&scb->lock); + spin_unlock_irqrestore(&scb->lock, flags); cs46xx_dsp_proc_free_scb_desc(scb); snd_assert (scb->scb_symbol != NULL, return ); -- 2.30.2