net/axgbe: fix double unlock

[ upstream commit c8c2296 ]

One issue caught by Coverity 340835
*unlock: axgbe_phy_set_mode unlocks pdata->phy_mutex
*double_unlock: axgbe_phy_sfp_detect unlocks pdata->phy_mutex
while it is unlocked.

In axgbe_phy_sfp_detect()/axgbe_phy_set_redrv_mode(),
axgbe_phy_get_comm_ownership() and axgbe_phy_put_comm_ownership()
are invoked subsequently.

Currently in axgbe_phy_get_comm_ownership(), during one of the case
'phy_data->comm_owned' is not protected and before returning 0, lock is
not called and unlock is called in axgbe_phy_put_comm_ownership()
directly which is incorrect.

Ideally, the variable 'phy_data->comm_owned' needs to be protected.
During success scenario, lock is called in
axgbe_phy_get_comm_ownership() followed by unlock in
axgbe_phy_put_comm_ownership().  In failure case, unlock is invoked in
axgbe_phy_get_comm_ownership() itself appropriately.

The fix is to protect 'phy_data->comm_owned' in the identified case
ensuring locks/unlocks properly exist.

Coverity issue: 340835
Fixes: a5c7273 ("net/axgbe: add phy programming APIs")

Signed-off-by: Pallantla Poornima <pallantlax.poornima@intel.com>
Acked-by: Ravi Kumar <ravi1.kumar@amd.com>

drivers/net/axgbe/axgbe_phy_impl.c

@@ -412,15 +412,15 @@ static int axgbe_phy_get_comm_ownership(struct axgbe_port *pdata)
 	uint64_t timeout;
 	unsigned int mutex_id;
 
-	if (phy_data->comm_owned)
-		return 0;
-
 	/* The I2C and MDIO/GPIO bus is multiplexed between multiple devices,
 	 * the driver needs to take the software mutex and then the hardware
 	 * mutexes before being able to use the busses.
 	 */
 	pthread_mutex_lock(&pdata->phy_mutex);
 
+	if (phy_data->comm_owned)
+		return 0;
+
 	/* Clear the mutexes */
 	XP_IOWRITE(pdata, XP_I2C_MUTEX, AXGBE_MUTEX_RELEASE);
 	XP_IOWRITE(pdata, XP_MDIO_MUTEX, AXGBE_MUTEX_RELEASE);