linux-kernel - [PATCH AUTOSEL 4.18 023/131] media: usbtv: use irqsave() in USB's complete callback

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Date:   Sun, 2 Sep 2018 13:03:27 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL 4.18 023/131] media: usbtv: use irqsave() in USB's
 complete callback

From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>

[ Upstream commit 320905baa1dbddd3991c287432176d536e1d5b79 ]

The USB completion callback does not disable interrupts while acquiring
the lock. We want to remove the local_irq_disable() invocation from
__usb_hcd_giveback_urb() and therefore it is required for the callback
handler to disable the interrupts while acquiring the lock.
The callback may be invoked either in IRQ or BH context depending on the
USB host controller.
Use the _irqsave() variant of the locking primitives.

Cc: Hans Verkuil <hans.verkuil@...co.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/media/usb/usbtv/usbtv-audio.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/usbtv/usbtv-audio.c b/drivers/media/usb/usbtv/usbtv-audio.c
index 2c2ca77fa01f..4ce38246ed64 100644
--- a/drivers/media/usb/usbtv/usbtv-audio.c
+++ b/drivers/media/usb/usbtv/usbtv-audio.c
@@ -126,6 +126,7 @@ static void usbtv_audio_urb_received(struct urb *urb)
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	size_t i, frame_bytes, chunk_length, buffer_pos, period_pos;
 	int period_elapsed;
+	unsigned long flags;
 	void *urb_current;
 
 	switch (urb->status) {
@@ -179,12 +180,12 @@ static void usbtv_audio_urb_received(struct urb *urb)
 		}
 	}
 
-	snd_pcm_stream_lock(substream);
+	snd_pcm_stream_lock_irqsave(substream, flags);
 
 	chip->snd_buffer_pos = buffer_pos;
 	chip->snd_period_pos = period_pos;
 
-	snd_pcm_stream_unlock(substream);
+	snd_pcm_stream_unlock_irqrestore(substream, flags);
 
 	if (period_elapsed)
 		snd_pcm_period_elapsed(substream);
-- 
2.17.1