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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     John Keeping <john@metanate.com>, Vinod Koul <vkoul@kernel.org>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL 4.18 25/88] dmaengine: pl330: fix irq race with
 terminate_all
Thread-Topic: [PATCH AUTOSEL 4.18 25/88] dmaengine: pl330: fix irq race with
 terminate_all
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Date:   Fri, 7 Sep 2018 00:36:09 +0000
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From: John Keeping <john@metanate.com>

[ Upstream commit e49756544a21f5625b379b3871d27d8500764670 ]

In pl330_update() when checking if a channel has been aborted, the
channel's lock is not taken, only the overall pl330_dmac lock.  But in
pl330_terminate_all() the aborted flag (req_running=3D=3D-1) is set under
the channel lock and not the pl330_dmac lock.

With threaded interrupts, this leads to a potential race:

    pl330_terminate_all	        pl330_update
    -------------------         ------------
    lock channel
                                entry
    lock pl330
    _stop channel
    unlock pl330
                                lock pl330
                                check req_running !=3D -1
    req_running =3D -1
                                _start channel

Signed-off-by: John Keeping <john@metanate.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/dma/pl330.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index de0957fe9668..bb6dfa2e1e8a 100644
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -2257,13 +2257,14 @@ static int pl330_terminate_all(struct dma_chan *cha=
n)
=20
 	pm_runtime_get_sync(pl330->ddma.dev);
 	spin_lock_irqsave(&pch->lock, flags);
+
 	spin_lock(&pl330->lock);
 	_stop(pch->thread);
-	spin_unlock(&pl330->lock);
-
 	pch->thread->req[0].desc =3D NULL;
 	pch->thread->req[1].desc =3D NULL;
 	pch->thread->req_running =3D -1;
+	spin_unlock(&pl330->lock);
+
 	power_down =3D pch->active;
 	pch->active =3D false;
=20
--=20
2.17.1