[ 3.8.y.z extended stable ] Patch "staging: android: logger: Correct write offset reset on error" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    staging: android: logger: Correct write offset reset on error

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.7.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 52898157f67e449dedf5e258f970d398d4ba3de3 Mon Sep 17 00:00:00 2001
From: Karlis Ogsts <karlis.ogsts at sonymobile.com>
Date: Mon, 22 Jul 2013 13:51:42 -0700
Subject: staging: android: logger: Correct write offset reset on error

commit 72bb99cfe9c57d2044445fb34bbc95b4c0bae6f2 upstream.

In the situation that a writer fails to copy data from userspace it will reset
the write offset to the value it had before it went to sleep. This discarding
any messages written while aquiring the mutex.

Therefore the reset offset needs to be retrieved after acquiring the mutex.

Cc: Android Kernel Team <kernel-team at android.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson at sonymobile.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/staging/android/logger.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/android/logger.c b/drivers/staging/android/logger.c
index dbc63cb..316cb2c 100644
--- a/drivers/staging/android/logger.c
+++ b/drivers/staging/android/logger.c
@@ -371,7 +371,7 @@ static ssize_t logger_aio_write(struct kiocb *iocb, const struct iovec *iov,
 			 unsigned long nr_segs, loff_t ppos)
 {
 	struct logger_log *log = file_get_log(iocb->ki_filp);
-	size_t orig = log->w_off;
+	size_t orig;
 	struct logger_entry header;
 	struct timespec now;
 	ssize_t ret = 0;
@@ -390,6 +390,8 @@ static ssize_t logger_aio_write(struct kiocb *iocb, const struct iovec *iov,

 	mutex_lock(&log->mutex);

+	orig = log->w_off;
+
 	/*
 	 * Fix up any readers, pulling them forward to the first readable
 	 * entry after (what will be) the new write offset. We do this now
--
1.8.1.2