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Subject[65/85] drivers/dma/pl330.c: fix locking in pl330_free_chan_resources()
3.2.49-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>

commit da331ba8e9c5de72a27e50f71105395bba6eebe0 upstream.

tasklet_kill() may sleep so call it before taking pch->lock.

Fixes following lockup:

BUG: scheduling while atomic: cat/2383/0x00000002
Modules linked in:
unwind_backtrace+0x0/0xfc
__schedule_bug+0x4c/0x58
__schedule+0x690/0x6e0
sys_sched_yield+0x70/0x78
tasklet_kill+0x34/0x8c
pl330_free_chan_resources+0x24/0x88
dma_chan_put+0x4c/0x50
[...]
BUG: spinlock lockup suspected on CPU#0, swapper/0/0
lock: 0xe52aa04c, .magic: dead4ead, .owner: cat/2383, .owner_cpu: 1
unwind_backtrace+0x0/0xfc
do_raw_spin_lock+0x194/0x204
_raw_spin_lock_irqsave+0x20/0x28
pl330_tasklet+0x2c/0x5a8
tasklet_action+0xfc/0x114
__do_softirq+0xe4/0x19c
irq_exit+0x98/0x9c
handle_IPI+0x124/0x16c
gic_handle_irq+0x64/0x68
__irq_svc+0x40/0x70
cpuidle_wrap_enter+0x4c/0xa0
cpuidle_enter_state+0x18/0x68
cpuidle_idle_call+0xac/0xe0
cpu_idle+0xac/0xf0

Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Jassi Brar <jassisinghbrar@gmail.com>
Cc: Vinod Koul <vinod.koul@linux.intel.com>
Cc: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/dma/pl330.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -349,10 +349,10 @@ static void pl330_free_chan_resources(st
struct dma_pl330_chan *pch = to_pchan(chan);
unsigned long flags;

- spin_lock_irqsave(&pch->lock, flags);
-
tasklet_kill(&pch->task);

+ spin_lock_irqsave(&pch->lock, flags);
+
pl330_release_channel(pch->pl330_chid);
pch->pl330_chid = NULL;



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