linux-kernel - [PATCH AUTOSEL 4.4 01/30] usb: usbtest: use irqsave() in USB's complete callback

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Message-ID: <20180907003853.57942-1-alexander.levin@microsoft.com>
Date:   Fri, 7 Sep 2018 00:38:56 +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>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL 4.4 01/30] usb: usbtest: use irqsave() in USB's
 complete callback

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

[ Upstream commit 6f3fde684d0232e66ada3410f016a58e09a87689 ]

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: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Acked-by: Alan Stern <stern@...land.harvard.edu>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/usb/misc/usbtest.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/misc/usbtest.c b/drivers/usb/misc/usbtest.c
index bc92a498ec03..4632a29d5403 100644
--- a/drivers/usb/misc/usbtest.c
+++ b/drivers/usb/misc/usbtest.c
@@ -1053,11 +1053,12 @@ static void ctrl_complete(struct urb *urb)
 	struct usb_ctrlrequest	*reqp;
 	struct subcase		*subcase;
 	int			status = urb->status;
+	unsigned long		flags;
 
 	reqp = (struct usb_ctrlrequest *)urb->setup_packet;
 	subcase = container_of(reqp, struct subcase, setup);
 
-	spin_lock(&ctx->lock);
+	spin_lock_irqsave(&ctx->lock, flags);
 	ctx->count--;
 	ctx->pending--;
 
@@ -1156,7 +1157,7 @@ static void ctrl_complete(struct urb *urb)
 	/* signal completion when nothing's queued */
 	if (ctx->pending == 0)
 		complete(&ctx->complete);
-	spin_unlock(&ctx->lock);
+	spin_unlock_irqrestore(&ctx->lock, flags);
 }
 
 static int
@@ -1832,8 +1833,9 @@ struct transfer_context {
 static void complicated_callback(struct urb *urb)
 {
 	struct transfer_context	*ctx = urb->context;
+	unsigned long flags;
 
-	spin_lock(&ctx->lock);
+	spin_lock_irqsave(&ctx->lock, flags);
 	ctx->count--;
 
 	ctx->packet_count += urb->number_of_packets;
@@ -1873,7 +1875,7 @@ static void complicated_callback(struct urb *urb)
 		complete(&ctx->done);
 	}
 done:
-	spin_unlock(&ctx->lock);
+	spin_unlock_irqrestore(&ctx->lock, flags);
 }
 
 static struct urb *iso_alloc_urb(
-- 
2.17.1