Commit 34737e13 authored by Loic Poulain's avatar Loic Poulain Committed by David S. Miller
Browse files

net: wwan: mhi_wwan_ctrl: Fix possible deadlock 



Lockdep detected possible interrupt unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&mhiwwan->rx_lock);
                               local_irq_disable();
                               lock(&mhi_cntrl->pm_lock);
                               lock(&mhiwwan->rx_lock);
   <Interrupt>
     lock(&mhi_cntrl->pm_lock);

  *** DEADLOCK ***

To prevent this we need to disable the soft-interrupts when taking
the rx_lock.

Cc: stable@vger.kernel.org
Fixes: fa588eba ("net: Add Qcom WWAN control driver")
Reported-by: default avatarThomas Perrot <thomas.perrot@bootlin.com>
Signed-off-by: default avatarLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: default avatarSergey Ryazanov <ryazanov.s.a@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 47fac456

drivers/net/wwan/mhi_wwan_ctrl.c

+6 −6
Original line number Diff line number Diff line
@@ -41,14 +41,14 @@ struct mhi_wwan_dev { 
/* Increment RX budget and schedule RX refill if necessary */

static void mhi_wwan_rx_budget_inc(struct mhi_wwan_dev *mhiwwan)

{

	spin_lock(&mhiwwan->rx_lock);

	spin_lock_bh(&mhiwwan->rx_lock);



	mhiwwan->rx_budget++;



	if (test_bit(MHI_WWAN_RX_REFILL, &mhiwwan->flags))

		schedule_work(&mhiwwan->rx_refill);



	spin_unlock(&mhiwwan->rx_lock);

	spin_unlock_bh(&mhiwwan->rx_lock);

}



/* Decrement RX budget if non-zero and return true on success */
@@ -56,7 +56,7 @@ static bool mhi_wwan_rx_budget_dec(struct mhi_wwan_dev *mhiwwan) 
{

	bool ret = false;



	spin_lock(&mhiwwan->rx_lock);

	spin_lock_bh(&mhiwwan->rx_lock);



	if (mhiwwan->rx_budget) {

		mhiwwan->rx_budget--;
@@ -64,7 +64,7 @@ static bool mhi_wwan_rx_budget_dec(struct mhi_wwan_dev *mhiwwan) 
			ret = true;

	}



	spin_unlock(&mhiwwan->rx_lock);

	spin_unlock_bh(&mhiwwan->rx_lock);



	return ret;

}
@@ -130,9 +130,9 @@ static void mhi_wwan_ctrl_stop(struct wwan_port *port) 
{

	struct mhi_wwan_dev *mhiwwan = wwan_port_get_drvdata(port);



	spin_lock(&mhiwwan->rx_lock);

	spin_lock_bh(&mhiwwan->rx_lock);

	clear_bit(MHI_WWAN_RX_REFILL, &mhiwwan->flags);

	spin_unlock(&mhiwwan->rx_lock);

	spin_unlock_bh(&mhiwwan->rx_lock);



	cancel_work_sync(&mhiwwan->rx_refill);