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: fa588eba632d ("net: Add Qcom WWAN control driver")
Reported-by: Thomas Perrot <thomas.perrot@bootlin.com>
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Reviewed-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/wwan/mhi_wwan_ctrl.c b/drivers/net/wwan/mhi_wwan_ctrl.c
index 1e18420..d0a98f3 100644 (file)
--- a/drivers/net/wwan/mhi_wwan_ctrl.c
+++ b/drivers/net/wwan/mhi_wwan_ctrl.c
@@ -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);