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authorArjan van de Ven <arjan@infradead.org>2006-07-04 06:07:22 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-07-04 13:24:57 -0400
commitc6482dde1c2811afba289b2344268f850595f350 (patch)
treebfd2ab0c2bcfe6fe4de64bab40f2c19f25131a97
parenta46f9484f8926aacb2e79a0e1676de3a6a6fbae8 (diff)
[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 <arjan@linux.intel.com> Cc: Jaroslav Kysela <perex@suse.cz> Acked-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--sound/pci/cs46xx/dsp_spos_scb_lib.c5
1 files 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
180void cs46xx_dsp_remove_scb (struct snd_cs46xx *chip, struct dsp_scb_descriptor * scb) 180void cs46xx_dsp_remove_scb (struct snd_cs46xx *chip, struct dsp_scb_descriptor * scb)
181{ 181{
182 struct dsp_spos_instance * ins = chip->dsp_spos_instance; 182 struct dsp_spos_instance * ins = chip->dsp_spos_instance;
183 unsigned long flags;
183 184
184 /* check integrety */ 185 /* check integrety */
185 snd_assert ( (scb->index >= 0 && 186 snd_assert ( (scb->index >= 0 &&
@@ -194,9 +195,9 @@ void cs46xx_dsp_remove_scb (struct snd_cs46xx *chip, struct dsp_scb_descriptor *
194 goto _end); 195 goto _end);
195#endif 196#endif
196 197
197 spin_lock(&scb->lock); 198 spin_lock_irqsave(&scb->lock, flags);
198 _dsp_unlink_scb (chip,scb); 199 _dsp_unlink_scb (chip,scb);
199 spin_unlock(&scb->lock); 200 spin_unlock_irqrestore(&scb->lock, flags);
200 201
201 cs46xx_dsp_proc_free_scb_desc(scb); 202 cs46xx_dsp_proc_free_scb_desc(scb);
202 snd_assert (scb->scb_symbol != NULL, return ); 203 snd_assert (scb->scb_symbol != NULL, return );