i2c: piix4: Request the SMBUS semaphore inside the mutex

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>

diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index 73cc6799cc59b2e8a502c927dae28b80831f34b8..c21ca7bf2efe4f02d420ef53c679b321eceb8fe6 100644 (file)
--- 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_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;
 }