Patch "bus: mhi: ep: Change state_lock to mutex" has been added to the 6.1-stable tree

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This is a note to let you know that I've just added the patch titled

    bus: mhi: ep: Change state_lock to mutex

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     bus-mhi-ep-change-state_lock-to-mutex.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit ca1fb2dad4ed43e57a052e9aab6c587bdc208ea5
Author: Manivannan Sadhasivam <mani@xxxxxxxxxx>
Date:   Mon Jan 23 12:59:45 2023 +0530

    bus: mhi: ep: Change state_lock to mutex
    
    [ Upstream commit 1ddc7618294084fff8d673217a9479550990ee84 ]
    
    state_lock, the spinlock type is meant to protect race against concurrent
    MHI state transitions. In mhi_ep_set_m0_state(), while the state_lock is
    being held, the channels are resumed in mhi_ep_resume_channels() if the
    previous state was M3. This causes sleeping in atomic bug, since
    mhi_ep_resume_channels() use mutex internally.
    
    Since the state_lock is supposed to be held throughout the state change,
    it is not ideal to drop the lock before calling mhi_ep_resume_channels().
    So to fix this issue, let's change the type of state_lock to mutex. This
    would also allow holding the lock throughout all state transitions thereby
    avoiding any potential race.
    
    Cc: <stable@xxxxxxxxxxxxxxx> # 5.19
    Fixes: e4b7b5f0f30a ("bus: mhi: ep: Add support for suspending and resuming channels")
    Reported-by: Dan Carpenter <error27@xxxxxxxxx>
    Reviewed-by: Jeffrey Hugo <quic_jhugo@xxxxxxxxxxx>
    Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
index b06548005985c..edd153dda40c0 100644
--- a/drivers/bus/mhi/ep/main.c
+++ b/drivers/bus/mhi/ep/main.c
@@ -994,11 +994,11 @@ static void mhi_ep_reset_worker(struct work_struct *work)
 
 	mhi_ep_power_down(mhi_cntrl);
 
-	spin_lock_bh(&mhi_cntrl->state_lock);
+	mutex_lock(&mhi_cntrl->state_lock);
+
 	/* Reset MMIO to signal host that the MHI_RESET is completed in endpoint */
 	mhi_ep_mmio_reset(mhi_cntrl);
 	cur_state = mhi_cntrl->mhi_state;
-	spin_unlock_bh(&mhi_cntrl->state_lock);
 
 	/*
 	 * Only proceed further if the reset is due to SYS_ERR. The host will
@@ -1007,6 +1007,8 @@ static void mhi_ep_reset_worker(struct work_struct *work)
 	 */
 	if (cur_state == MHI_STATE_SYS_ERR)
 		mhi_ep_power_up(mhi_cntrl);
+
+	mutex_unlock(&mhi_cntrl->state_lock);
 }
 
 /*
@@ -1379,8 +1381,8 @@ int mhi_ep_register_controller(struct mhi_ep_cntrl *mhi_cntrl,
 
 	INIT_LIST_HEAD(&mhi_cntrl->st_transition_list);
 	INIT_LIST_HEAD(&mhi_cntrl->ch_db_list);
-	spin_lock_init(&mhi_cntrl->state_lock);
 	spin_lock_init(&mhi_cntrl->list_lock);
+	mutex_init(&mhi_cntrl->state_lock);
 	mutex_init(&mhi_cntrl->event_lock);
 
 	/* Set MHI version and AMSS EE before enumeration */
diff --git a/drivers/bus/mhi/ep/sm.c b/drivers/bus/mhi/ep/sm.c
index 3655c19e23c7b..fd200b2ac0bb2 100644
--- a/drivers/bus/mhi/ep/sm.c
+++ b/drivers/bus/mhi/ep/sm.c
@@ -63,24 +63,23 @@ int mhi_ep_set_m0_state(struct mhi_ep_cntrl *mhi_cntrl)
 	int ret;
 
 	/* If MHI is in M3, resume suspended channels */
-	spin_lock_bh(&mhi_cntrl->state_lock);
+	mutex_lock(&mhi_cntrl->state_lock);
+
 	old_state = mhi_cntrl->mhi_state;
 	if (old_state == MHI_STATE_M3)
 		mhi_ep_resume_channels(mhi_cntrl);
 
 	ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_M0);
-	spin_unlock_bh(&mhi_cntrl->state_lock);
-
 	if (ret) {
 		mhi_ep_handle_syserr(mhi_cntrl);
-		return ret;
+		goto err_unlock;
 	}
 
 	/* Signal host that the device moved to M0 */
 	ret = mhi_ep_send_state_change_event(mhi_cntrl, MHI_STATE_M0);
 	if (ret) {
 		dev_err(dev, "Failed sending M0 state change event\n");
-		return ret;
+		goto err_unlock;
 	}
 
 	if (old_state == MHI_STATE_READY) {
@@ -88,11 +87,14 @@ int mhi_ep_set_m0_state(struct mhi_ep_cntrl *mhi_cntrl)
 		ret = mhi_ep_send_ee_event(mhi_cntrl, MHI_EE_AMSS);
 		if (ret) {
 			dev_err(dev, "Failed sending AMSS EE event\n");
-			return ret;
+			goto err_unlock;
 		}
 	}
 
-	return 0;
+err_unlock:
+	mutex_unlock(&mhi_cntrl->state_lock);
+
+	return ret;
 }
 
 int mhi_ep_set_m3_state(struct mhi_ep_cntrl *mhi_cntrl)
@@ -100,13 +102,12 @@ int mhi_ep_set_m3_state(struct mhi_ep_cntrl *mhi_cntrl)
 	struct device *dev = &mhi_cntrl->mhi_dev->dev;
 	int ret;
 
-	spin_lock_bh(&mhi_cntrl->state_lock);
-	ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_M3);
-	spin_unlock_bh(&mhi_cntrl->state_lock);
+	mutex_lock(&mhi_cntrl->state_lock);
 
+	ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_M3);
 	if (ret) {
 		mhi_ep_handle_syserr(mhi_cntrl);
-		return ret;
+		goto err_unlock;
 	}
 
 	mhi_ep_suspend_channels(mhi_cntrl);
@@ -115,10 +116,13 @@ int mhi_ep_set_m3_state(struct mhi_ep_cntrl *mhi_cntrl)
 	ret = mhi_ep_send_state_change_event(mhi_cntrl, MHI_STATE_M3);
 	if (ret) {
 		dev_err(dev, "Failed sending M3 state change event\n");
-		return ret;
+		goto err_unlock;
 	}
 
-	return 0;
+err_unlock:
+	mutex_unlock(&mhi_cntrl->state_lock);
+
+	return ret;
 }
 
 int mhi_ep_set_ready_state(struct mhi_ep_cntrl *mhi_cntrl)
@@ -127,22 +131,24 @@ int mhi_ep_set_ready_state(struct mhi_ep_cntrl *mhi_cntrl)
 	enum mhi_state mhi_state;
 	int ret, is_ready;
 
-	spin_lock_bh(&mhi_cntrl->state_lock);
+	mutex_lock(&mhi_cntrl->state_lock);
+
 	/* Ensure that the MHISTATUS is set to RESET by host */
 	mhi_state = mhi_ep_mmio_masked_read(mhi_cntrl, EP_MHISTATUS, MHISTATUS_MHISTATE_MASK);
 	is_ready = mhi_ep_mmio_masked_read(mhi_cntrl, EP_MHISTATUS, MHISTATUS_READY_MASK);
 
 	if (mhi_state != MHI_STATE_RESET || is_ready) {
 		dev_err(dev, "READY state transition failed. MHI host not in RESET state\n");
-		spin_unlock_bh(&mhi_cntrl->state_lock);
-		return -EIO;
+		ret = -EIO;
+		goto err_unlock;
 	}
 
 	ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_READY);
-	spin_unlock_bh(&mhi_cntrl->state_lock);
-
 	if (ret)
 		mhi_ep_handle_syserr(mhi_cntrl);
 
+err_unlock:
+	mutex_unlock(&mhi_cntrl->state_lock);
+
 	return ret;
 }
diff --git a/include/linux/mhi_ep.h b/include/linux/mhi_ep.h
index 478aece170462..f198a8ac7ee72 100644
--- a/include/linux/mhi_ep.h
+++ b/include/linux/mhi_ep.h
@@ -70,8 +70,8 @@ struct mhi_ep_db_info {
  * @cmd_ctx_cache_phys: Physical address of the host command context cache
  * @chdb: Array of channel doorbell interrupt info
  * @event_lock: Lock for protecting event rings
- * @list_lock: Lock for protecting state transition and channel doorbell lists
  * @state_lock: Lock for protecting state transitions
+ * @list_lock: Lock for protecting state transition and channel doorbell lists
  * @st_transition_list: List of state transitions
  * @ch_db_list: List of queued channel doorbells
  * @wq: Dedicated workqueue for handling rings and state changes
@@ -117,8 +117,8 @@ struct mhi_ep_cntrl {
 
 	struct mhi_ep_db_info chdb[4];
 	struct mutex event_lock;
+	struct mutex state_lock;
 	spinlock_t list_lock;
-	spinlock_t state_lock;
 
 	struct list_head st_transition_list;
 	struct list_head ch_db_list;



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