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Groups > linux.kernel > #1667085

[PATCH 4.9 021/108] i2c: piix4: Request the SMBUS semaphore inside the mutex

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4.9-stable review patch.  If anyone has any objections, please let me know.

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

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;
 }
 

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[PATCH 4.9 000/108] 4.9.33-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-15 20:30 +0200
  [PATCH 4.9 021/108] i2c: piix4: Request the SMBUS semaphore inside the mutex Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-15 20:30 +0200
  [PATCH 4.9 006/108] ibmvnic: Fix endian error when requesting device capabilities Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-15 20:30 +0200
  [PATCH 4.9 034/108] log2: make order_base_2() behave correctly on const input value zero Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-15 20:30 +0200
  [PATCH 4.9 010/108] ipv6: Handle IPv4-mapped src to in6addr_any dst. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-15 20:30 +0200
  [PATCH 4.9 031/108] jump label: pass kbuild_cflags when checking for asm goto support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-15 20:30 +0200
    Re: [PATCH 4.9 031/108] jump label: pass kbuild_cflags when checking  for asm goto support Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org> - 2017-06-19 17:30 +0200
  [PATCH 4.9 007/108] net: xilinx_emaclite: fix freezes due to unordered I/O Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-15 20:30 +0200
  [PATCH 4.9 016/108] ibmvnic: Initialize completion variables before starting work Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-15 20:30 +0200
  [PATCH 4.9 017/108] NET: mkiss: Fix panic Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-15 20:30 +0200
  [PATCH 4.9 004/108] netfilter: nf_conntrack_sip: fix wrong memory initialisation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-15 20:30 +0200
  [PATCH 4.9 040/108] fscache: Clear outstanding writes when disabling a cookie Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-15 20:30 +0200
  [PATCH 4.9 066/108] nfs: Fix "Dont increment lock sequence ID after NFS4ERR_MOVED" Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-06-15 20:40 +0200
  Re: [PATCH 4.9 000/108] 4.9.33-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-06-16 00:30 +0200
  Re: [PATCH 4.9 000/108] 4.9.33-stable review Guenter Roeck <linux@roeck-us.net> - 2017-06-16 02:50 +0200

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