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i2c: piix4: Request the SMBUS semaphore inside the mutex

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[ Upstream commit bbb27fc33d ]

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

Fixes: 701dc207bf ("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>
This commit is contained in:
Ricardo Ribalda 2017-05-23 21:53:44 -04:00 committed by Greg Kroah-Hartman
parent 7a6fcf38fa
commit c1a4306f24
1 changed files with 7 additions and 5 deletions
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12
drivers/i2c/busses/i2c-piix4.c
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@ -592,6 +592,8 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
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_adapter *adap, u16 addr,
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_adapter *adap, u16 addr,
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;
}