linux-kernel - [PATCH 3.16 17/61] drivers: usb: core: Minimize irq disabling in usb_sg

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Message-ID: <lsq.1591725832.694160445@decadent.org.uk>
Date:   Tue, 09 Jun 2020 19:04:08 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Alan Stern" <stern@...land.harvard.edu>,
        "David Mosberger" <davidm@...uge.net>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>
Subject: [PATCH 3.16 17/61] drivers: usb: core: Minimize irq disabling in
 usb_sg_cancel()

3.16.85-rc1 review patch.  If anyone has any objections, please let me know.

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

From: David Mosberger <davidm@...uge.net>

commit 5f2e5fb873e269fcb806165715d237f0de4ecf1d upstream.

Restructure usb_sg_cancel() so we don't have to disable interrupts
while cancelling the URBs.

Suggested-by: Alan Stern <stern@...land.harvard.edu>
Signed-off-by: David Mosberger <davidm@...uge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/usb/core/message.c | 37 +++++++++++++++++--------------------
 1 file changed, 17 insertions(+), 20 deletions(-)

--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -581,31 +581,28 @@ EXPORT_SYMBOL_GPL(usb_sg_wait);
 void usb_sg_cancel(struct usb_sg_request *io)
 {
 	unsigned long flags;
+	int i, retval;
 
 	spin_lock_irqsave(&io->lock, flags);
+	if (io->status) {
+		spin_unlock_irqrestore(&io->lock, flags);
+		return;
+	}
+	/* shut everything down */
+	io->status = -ECONNRESET;
+	spin_unlock_irqrestore(&io->lock, flags);
 
-	/* shut everything down, if it didn't already */
-	if (!io->status) {
-		int i;
-
-		io->status = -ECONNRESET;
-		spin_unlock(&io->lock);
-		for (i = 0; i < io->entries; i++) {
-			int retval;
-
-			usb_block_urb(io->urbs[i]);
+	for (i = io->entries - 1; i >= 0; --i) {
+		usb_block_urb(io->urbs[i]);
 
-			retval = usb_unlink_urb(io->urbs[i]);
-			if (retval != -EINPROGRESS
-					&& retval != -ENODEV
-					&& retval != -EBUSY
-					&& retval != -EIDRM)
-				dev_warn(&io->dev->dev, "%s, unlink --> %d\n",
-					__func__, retval);
-		}
-		spin_lock(&io->lock);
+		retval = usb_unlink_urb(io->urbs[i]);
+		if (retval != -EINPROGRESS
+		    && retval != -ENODEV
+		    && retval != -EBUSY
+		    && retval != -EIDRM)
+			dev_warn(&io->dev->dev, "%s, unlink --> %d\n",
+				 __func__, retval);
 	}
-	spin_unlock_irqrestore(&io->lock, flags);
 }
 EXPORT_SYMBOL_GPL(usb_sg_cancel);