From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Sat, 21 Dec 2013 18:10:00 +0000 (-0800)
Subject: 3.4-stable patches
X-Git-Tag: v3.4.76~79
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=38255eb226ae7d8685a2c9e2c2613f3df2359f41;p=thirdparty%2Fkernel%2Fstable-queue.git

3.4-stable patches

added patches:
	usb-serial-fix-race-in-generic-write.patch
---

diff --git a/queue-3.4/series b/queue-3.4/series
new file mode 100644
index 00000000000..f351a020bbc
--- /dev/null
+++ b/queue-3.4/series
@@ -0,0 +1 @@
+usb-serial-fix-race-in-generic-write.patch
diff --git a/queue-3.4/usb-serial-fix-race-in-generic-write.patch b/queue-3.4/usb-serial-fix-race-in-generic-write.patch
new file mode 100644
index 00000000000..cb80fb6ef76
--- /dev/null
+++ b/queue-3.4/usb-serial-fix-race-in-generic-write.patch
@@ -0,0 +1,47 @@
+From 6f6485463aada1ec6a0f3db6a03eb8e393d6bb55 Mon Sep 17 00:00:00 2001
+From: Johan Hovold <jhovold@gmail.com>
+Date: Sat, 9 Nov 2013 12:38:09 +0100
+Subject: USB: serial: fix race in generic write
+
+From: Johan Hovold <jhovold@gmail.com>
+
+commit 6f6485463aada1ec6a0f3db6a03eb8e393d6bb55 upstream.
+
+Fix race in generic write implementation, which could lead to
+temporarily degraded throughput.
+
+The current generic write implementation introduced by commit
+27c7acf22047 ("USB: serial: reimplement generic fifo-based writes") has
+always had this bug, although it's fairly hard to trigger and the
+consequences are not likely to be noticed.
+
+Specifically, a write() on one CPU while the completion handler is
+running on another could result in only one of the two write urbs being
+utilised to empty the remainder of the write fifo (unless there is a
+second write() that doesn't race during that time).
+
+Signed-off-by: Johan Hovold <jhovold@gmail.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/usb/serial/generic.c |    9 +--------
+ 1 file changed, 1 insertion(+), 8 deletions(-)
+
+--- a/drivers/usb/serial/generic.c
++++ b/drivers/usb/serial/generic.c
+@@ -223,14 +223,7 @@ retry:
+ 		return result;
+ 	}
+ 
+-	/* Try sending off another urb, unless in irq context (in which case
+-	 * there will be no free urb). */
+-	if (!in_irq())
+-		goto retry;
+-
+-	clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags);
+-
+-	return 0;
++	goto retry;	/* try sending off another urb */
+ }
+ 
+ /**