Patch "i2c: piix4: Request the SMBUS semaphore inside the mutex" has been added to the 4.9-stable tree

Patch "i2c: piix4: Request the SMBUS semaphore inside the mutex" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    i2c: piix4: Request the SMBUS semaphore inside the mutex

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     i2c-piix4-request-the-smbus-semaphore-inside-the-mutex.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Thu Jun 15 11:12:23 CEST 2017
From: Ricardo Ribalda <ricardo.ribalda@gmail.com>
Date: Tue, 23 May 2017 21:53:44 -0400
Subject: i2c: piix4: Request the SMBUS semaphore inside the mutex

From: Ricardo Ribalda <ricardo.ribalda@gmail.com>


[ Upstream commit bbb27fc33d44e7b8d96369810654df4ee1837566 ]

SMBSLVCNT must be protected with the piix4_mutex_sb800 in order to avoid
multiple buses accessing to the semaphore at the same time.

Fixes: 701dc207bf55 ("i2c: piix4: Avoid race conditions with IMC")
Reported-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/i2c/busses/i2c-piix4.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -592,6 +592,8 @@ static s32 piix4_access_sb800(struct i2c
 	u8 port;
 	int retval;
 
+	mutex_lock(&piix4_mutex_sb800);
+
 	/* Request the SMBUS semaphore, avoid conflicts with the IMC */
 	smbslvcnt  = inb_p(SMBSLVCNT);
 	do {
@@ -605,10 +607,10 @@ static s32 piix4_access_sb800(struct i2c
 		usleep_range(1000, 2000);
 	} while (--retries);
 	/* SMBus is still owned by the IMC, we give up */
-	if (!retries)
+	if (!retries) {
+		mutex_unlock(&piix4_mutex_sb800);
 		return -EBUSY;
-
-	mutex_lock(&piix4_mutex_sb800);
+	}
 
 	outb_p(piix4_port_sel_sb800, SB800_PIIX4_SMB_IDX);
 	smba_en_lo = inb_p(SB800_PIIX4_SMB_IDX + 1);
@@ -623,11 +625,11 @@ static s32 piix4_access_sb800(struct i2c
 
 	outb_p(smba_en_lo, SB800_PIIX4_SMB_IDX + 1);
 
-	mutex_unlock(&piix4_mutex_sb800);
-
 	/* Release the semaphore */
 	outb_p(smbslvcnt | 0x20, SMBSLVCNT);
 
+	mutex_unlock(&piix4_mutex_sb800);
+
 	return retval;
 }
 


Patches currently in stable-queue which might be from ricardo.ribalda@gmail.com are

queue-4.9/i2c-piix4-request-the-smbus-semaphore-inside-the-mutex.patch
queue-4.9/i2c-piix4-fix-request_region-size.patch