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Commit c4a0f6f2 authored by Hemant Kumar's avatar Hemant Kumar Committed by Gerrit - the friendly Code Review server
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mhi: core: Synchronize time sync operation and removal 



If time sync is requested by user space when endpoint is shutting
down dev_wake count gets incremented. This is causing assert when
shutdown API checks the dev_wake count and it is still non-zero.
Fix this issue by protecting time sync API and removal of time sync
under tsync_mutex. This helps to take care of a race condition when
time sync is requested while time sync remove in progress and also
makes sure that dev_wake count becomes zero when time sync remove
is done to prevent assert condition.

Change-Id: I4e758611613e541537dd900306aa81dd3b4a9f3a
Signed-off-by: default avatarHemant Kumar <hemantk@codeaurora.org>
parent e4f5f922

drivers/bus/mhi/core/mhi_init.c

+1 −1
Original line number Diff line number Diff line
@@ -603,7 +603,6 @@ int mhi_init_timesync(struct mhi_controller *mhi_cntrl) 
		return -ENOMEM;



	spin_lock_init(&mhi_tsync->lock);

	mutex_init(&mhi_tsync->lpm_mutex);

	INIT_LIST_HEAD(&mhi_tsync->head);

	init_completion(&mhi_tsync->completion);
@@ -1389,6 +1388,7 @@ int of_register_mhi_controller(struct mhi_controller *mhi_cntrl) 


	INIT_LIST_HEAD(&mhi_cntrl->transition_list);

	mutex_init(&mhi_cntrl->pm_mutex);

	mutex_init(&mhi_cntrl->tsync_mutex);

	rwlock_init(&mhi_cntrl->pm_lock);

	spin_lock_init(&mhi_cntrl->transition_lock);

	spin_lock_init(&mhi_cntrl->wlock);

drivers/bus/mhi/core/mhi_internal.h

+0 −1
Original line number Diff line number Diff line
@@ -725,7 +725,6 @@ struct mhi_timesync { 
	enum MHI_EV_CCS ccs;

	struct completion completion;

	spinlock_t lock; /* list protection */

	struct mutex lpm_mutex; /* lpm protection */

	struct list_head head;

};

drivers/bus/mhi/core/mhi_main.c

+18 −11
Original line number Diff line number Diff line
@@ -814,10 +814,12 @@ static const struct attribute_group mhi_tsync_group = { 
void mhi_destroy_timesync(struct mhi_controller *mhi_cntrl)

{

	if (mhi_cntrl->mhi_tsync) {

		mutex_lock(&mhi_cntrl->tsync_mutex);

		sysfs_remove_group(&mhi_cntrl->mhi_dev->dev.kobj,

				   &mhi_tsync_group);

		kfree(mhi_cntrl->mhi_tsync);

		mhi_cntrl->mhi_tsync = NULL;

		mutex_unlock(&mhi_cntrl->tsync_mutex);

	}

}
@@ -2462,16 +2464,17 @@ int mhi_get_remote_time_sync(struct mhi_device *mhi_dev, 
	struct mhi_timesync *mhi_tsync = mhi_cntrl->mhi_tsync;

	int ret;



	mutex_lock(&mhi_cntrl->tsync_mutex);

	/* not all devices support time feature */

	if (!mhi_tsync)

		return -EIO;

	if (!mhi_tsync) {

		ret = -EIO;

		goto err_unlock;

	}



	/* bring to M0 state */

	ret = __mhi_device_get_sync(mhi_cntrl);

	if (ret)

		return ret;



	mutex_lock(&mhi_tsync->lpm_mutex);

		goto err_unlock;



	read_lock_bh(&mhi_cntrl->pm_lock);

	if (unlikely(MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state))) {
@@ -2505,8 +2508,8 @@ int mhi_get_remote_time_sync(struct mhi_device *mhi_dev, 
error_invalid_state:

	mhi_cntrl->wake_put(mhi_cntrl, false);

	read_unlock_bh(&mhi_cntrl->pm_lock);

	mutex_unlock(&mhi_tsync->lpm_mutex);



err_unlock:

	mutex_unlock(&mhi_cntrl->tsync_mutex);

	return ret;

}

EXPORT_SYMBOL(mhi_get_remote_time_sync);
@@ -2534,13 +2537,16 @@ int mhi_get_remote_time(struct mhi_device *mhi_dev, 
	int ret;



	/* not all devices support time feature */

	if (!mhi_tsync)

		return -EIO;

	mutex_lock(&mhi_cntrl->tsync_mutex);

	if (!mhi_tsync) {

		ret = -EIO;

		goto err_unlock;

	}



	/* tsync db can only be rung in M0 state */

	ret = __mhi_device_get_sync(mhi_cntrl);

	if (ret)

		return ret;

		goto err_unlock;



	/*

	 * technically we can use GFP_KERNEL, but wants to avoid
@@ -2599,7 +2605,8 @@ int mhi_get_remote_time(struct mhi_device *mhi_dev, 
	read_lock_bh(&mhi_cntrl->pm_lock);

	mhi_cntrl->wake_put(mhi_cntrl, false);

	read_unlock_bh(&mhi_cntrl->pm_lock);



err_unlock:

	mutex_unlock(&mhi_cntrl->tsync_mutex);

	return ret;

}

EXPORT_SYMBOL(mhi_get_remote_time);

drivers/bus/mhi/core/mhi_pm.c

+3 −3
Original line number Diff line number Diff line
@@ -653,6 +653,9 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl, 
		sfr_info->buf_addr = NULL;

	}



	/* remove support for time sync */

	mhi_destroy_timesync(mhi_cntrl);



	mutex_lock(&mhi_cntrl->pm_mutex);



	MHI_ASSERT(atomic_read(&mhi_cntrl->dev_wake), "dev_wake != 0");
@@ -687,9 +690,6 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl, 
		er_ctxt->wp = er_ctxt->rbase;

	}



	/* remove support for time sync */

	mhi_destroy_timesync(mhi_cntrl);



	if (cur_state == MHI_PM_SYS_ERR_PROCESS) {

		mhi_ready_state_transition(mhi_cntrl);

	} else {

include/linux/mhi.h

+1 −0
Original line number Diff line number Diff line
@@ -319,6 +319,7 @@ struct mhi_controller { 


	/* caller should grab pm_mutex for suspend/resume operations */

	struct mutex pm_mutex;

	struct mutex tsync_mutex;

	bool pre_init;

	rwlock_t pm_lock;

	u32 pm_state;