The patch titled
fix AB-BA deadlock inversion at cs46xx_dsp_remove_scb
has been added to the -mm tree. Its filename is
fix-ab-ba-deadlock-inversion-at-cs46xx_dsp_remove_scb.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: fix AB-BA deadlock inversion at cs46xx_dsp_remove_scb
From: Arjan van de Ven <arjan@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
Cc: Jaroslav Kysela <perex@xxxxxxx>
Cc: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
sound/pci/cs46xx/dsp_spos_scb_lib.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff -puN sound/pci/cs46xx/dsp_spos_scb_lib.c~fix-ab-ba-deadlock-inversion-at-cs46xx_dsp_remove_scb sound/pci/cs46xx/dsp_spos_scb_lib.c
--- a/sound/pci/cs46xx/dsp_spos_scb_lib.c~fix-ab-ba-deadlock-inversion-at-cs46xx_dsp_remove_scb
+++ a/sound/pci/cs46xx/dsp_spos_scb_lib.c
@@ -180,6 +180,7 @@ static void _dsp_clear_sample_buffer (st
void cs46xx_dsp_remove_scb (struct snd_cs46xx *chip, struct dsp_scb_descriptor * scb)
{
struct dsp_spos_instance * ins = chip->dsp_spos_instance;
+ unsignded long flags;
/* check integrety */
snd_assert ( (scb->index >= 0 &&
@@ -194,9 +195,9 @@ void cs46xx_dsp_remove_scb (struct snd_c
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 );
_
Patches currently in -mm which might be from arjan@xxxxxxxxxxxxx are
origin.patch
fix-ab-ba-deadlock-inversion-at-cs46xx_dsp_remove_scb.patch
debug-shared-irqs.patch
vdso-print-fatal-signals.patch
vdso-improve-print_fatal_signals-support-by-adding-memory-maps.patch
-
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