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Commit 49ac45a4 authored by Eric Holmberg's avatar Eric Holmberg
Browse files

msm: smd_tty: Add locking hierarchy 



SMD TTY has several locks and it isn't clear what each lock manages.

Add a locking hierarchy and clarify locking scope.

Change-Id: I0026925a80548ef0025666d028b35e70d752a317
Signed-off-by: default avatarEric Holmberg <eholmber@codeaurora.org>
parent 7f6e6c78

arch/arm/mach-msm/smd_tty.c

+40 −37
Original line number Diff line number Diff line
@@ -76,18 +76,20 @@ static int smd_tty_probe_done; 
 * @ch_allocated:  completion set when SMD channel is allocated

 * @driver:  SMD channel platform driver context structure

 * @pil:  Peripheral Image Loader handle

 * @edge:  SMD edge associated with port

 * @ch_name:  SMD channel name associated with port

 * @dev_name:  SMD platform device name associated with port

 * @open_wait:  Timeout in seconds to wait for SMD port to be created / opened

 *

 * @reset_lock_lha2: lock for reset and open state

 * @in_reset:  True if SMD channel is closed / in SSR

 * @in_reset_updated:  reset state changed

 * @is_open:  True if SMD port is open

 * @open_wait:  Timeout in seconds to wait for SMD port to be created / opened

 * @ch_opened_wait_queue:  SMD port open/close wait queue

 * @reset_lock: lock for reset and open state

 * @ra_lock:  Read-available lock - used to synchronize reads from SMD

 *

 * @ra_lock_lha3:  Read-available lock - used to synchronize reads from SMD

 * @ra_wakeup_source_name: Name of the read-available wakeup source

 * @ra_wakeup_source:  Read-available wakeup source

 * @edge:  SMD edge associated with port

 * @ch_name:  SMD channel name associated with port

 * @dev_name:  SMD platform device name associated with port

 */

struct smd_tty_info {

	smd_channel_t *ch;
@@ -99,19 +101,20 @@ struct smd_tty_info { 
	struct completion ch_allocated;

	struct platform_driver driver;

	void *pil;

	uint32_t edge;

	char ch_name[SMD_MAX_CH_NAME_LEN];

	char dev_name[SMD_MAX_CH_NAME_LEN];

	unsigned int open_wait;



	spinlock_t reset_lock_lha2;

	int in_reset;

	int in_reset_updated;

	int is_open;

	unsigned int open_wait;

	wait_queue_head_t ch_opened_wait_queue;

	spinlock_t reset_lock;

	spinlock_t ra_lock;		/* Read Available Lock*/



	spinlock_t ra_lock_lha3;

	char ra_wakeup_source_name[MAX_RA_WAKE_LOCK_NAME_LEN];

	struct wakeup_source ra_wakeup_source;



	uint32_t edge;

	char ch_name[SMD_MAX_CH_NAME_LEN];

	char dev_name[SMD_MAX_CH_NAME_LEN];

};



/**
@@ -166,13 +169,13 @@ static void buf_req_retry(unsigned long param) 
	struct smd_tty_info *info = (struct smd_tty_info *)param;

	unsigned long flags;



	spin_lock_irqsave(&info->reset_lock, flags);

	spin_lock_irqsave(&info->reset_lock_lha2, flags);

	if (info->is_open) {

		spin_unlock_irqrestore(&info->reset_lock, flags);

		spin_unlock_irqrestore(&info->reset_lock_lha2, flags);

		tasklet_hi_schedule(&info->tty_tsklt);

		return;

	}

	spin_unlock_irqrestore(&info->reset_lock, flags);

	spin_unlock_irqrestore(&info->reset_lock_lha2, flags);

}



static ssize_t open_timeout_store(struct device *dev,
@@ -248,14 +251,14 @@ static void smd_tty_read(unsigned long param) 
		}



		if (test_bit(TTY_THROTTLED, &tty->flags)) break;

		spin_lock_irqsave(&info->ra_lock, flags);

		spin_lock_irqsave(&info->ra_lock_lha3, flags);

		avail = smd_read_avail(info->ch);

		if (avail == 0) {

			__pm_relax(&info->ra_wakeup_source);

			spin_unlock_irqrestore(&info->ra_lock, flags);

			spin_unlock_irqrestore(&info->ra_lock_lha3, flags);

			break;

		}

		spin_unlock_irqrestore(&info->ra_lock, flags);

		spin_unlock_irqrestore(&info->ra_lock_lha3, flags);



		if (avail > MAX_TTY_BUF_SIZE)

			avail = MAX_TTY_BUF_SIZE;
@@ -301,12 +304,12 @@ static void smd_tty_notify(void *priv, unsigned event) 


	switch (event) {

	case SMD_EVENT_DATA:

		spin_lock_irqsave(&info->reset_lock, flags);

		spin_lock_irqsave(&info->reset_lock_lha2, flags);

		if (!info->is_open) {

			spin_unlock_irqrestore(&info->reset_lock, flags);

			spin_unlock_irqrestore(&info->reset_lock_lha2, flags);

			break;

		}

		spin_unlock_irqrestore(&info->reset_lock, flags);

		spin_unlock_irqrestore(&info->reset_lock_lha2, flags);

		/* There may be clients (tty framework) that are blocked

		 * waiting for space to write data, so if a possible read

		 * interrupt came in wake anyone waiting and disable the
@@ -319,30 +322,30 @@ static void smd_tty_notify(void *priv, unsigned event) 
				wake_up_interruptible(&tty->write_wait);

			tty_kref_put(tty);

		}

		spin_lock_irqsave(&info->ra_lock, flags);

		spin_lock_irqsave(&info->ra_lock_lha3, flags);

		if (smd_read_avail(info->ch)) {

			__pm_stay_awake(&info->ra_wakeup_source);

			tasklet_hi_schedule(&info->tty_tsklt);

		}

		spin_unlock_irqrestore(&info->ra_lock, flags);

		spin_unlock_irqrestore(&info->ra_lock_lha3, flags);

		break;



	case SMD_EVENT_OPEN:

		spin_lock_irqsave(&info->reset_lock, flags);

		spin_lock_irqsave(&info->reset_lock_lha2, flags);

		info->in_reset = 0;

		info->in_reset_updated = 1;

		info->is_open = 1;

		wake_up_interruptible(&info->ch_opened_wait_queue);

		spin_unlock_irqrestore(&info->reset_lock, flags);

		spin_unlock_irqrestore(&info->reset_lock_lha2, flags);

		break;



	case SMD_EVENT_CLOSE:

		spin_lock_irqsave(&info->reset_lock, flags);

		spin_lock_irqsave(&info->reset_lock_lha2, flags);

		info->in_reset = 1;

		info->in_reset_updated = 1;

		info->is_open = 0;

		wake_up_interruptible(&info->ch_opened_wait_queue);

		spin_unlock_irqrestore(&info->reset_lock, flags);

		spin_unlock_irqrestore(&info->reset_lock_lha2, flags);

		/* schedule task to send TTY_BREAK */

		tasklet_hi_schedule(&info->tty_tsklt);
@@ -500,9 +503,9 @@ static void smd_tty_port_shutdown(struct tty_port *tport) 


	mutex_lock(&smd_tty_lock);



	spin_lock_irqsave(&info->reset_lock, flags);

	spin_lock_irqsave(&info->reset_lock_lha2, flags);

	info->is_open = 0;

	spin_unlock_irqrestore(&info->reset_lock, flags);

	spin_unlock_irqrestore(&info->reset_lock_lha2, flags);



	tasklet_kill(&info->tty_tsklt);

	wakeup_source_trash(&info->pending_ws);
@@ -581,13 +584,13 @@ static void smd_tty_unthrottle(struct tty_struct *tty) 
	struct smd_tty_info *info = tty->driver_data;

	unsigned long flags;



	spin_lock_irqsave(&info->reset_lock, flags);

	spin_lock_irqsave(&info->reset_lock_lha2, flags);

	if (info->is_open) {

		spin_unlock_irqrestore(&info->reset_lock, flags);

		spin_unlock_irqrestore(&info->reset_lock_lha2, flags);

		tasklet_hi_schedule(&info->tty_tsklt);

		return;

	}

	spin_unlock_irqrestore(&info->reset_lock, flags);

	spin_unlock_irqrestore(&info->reset_lock_lha2, flags);

}



/*
@@ -604,7 +607,7 @@ static int smd_tty_tiocmget(struct tty_struct *tty) 


	tiocm = smd_tiocmget(info->ch);



	spin_lock_irqsave(&info->reset_lock, flags);

	spin_lock_irqsave(&info->reset_lock_lha2, flags);

	tiocm |= (info->in_reset ? TIOCM_OUT1 : 0);

	if (info->in_reset_updated) {

		tiocm |= TIOCM_OUT2;
@@ -612,7 +615,7 @@ static int smd_tty_tiocmget(struct tty_struct *tty) 
	}

	SMD_TTY_INFO("PID %u --> %s TIOCM is %x ",

			current->pid, __func__, tiocm);

	spin_unlock_irqrestore(&info->reset_lock, flags);

	spin_unlock_irqrestore(&info->reset_lock_lha2, flags);



	return tiocm;

}
@@ -743,8 +746,8 @@ static int smd_tty_device_init(int idx) 
	smd_tty[idx].driver.probe = smd_tty_dummy_probe;

	smd_tty[idx].driver.driver.name = smd_tty[idx].dev_name;

	smd_tty[idx].driver.driver.owner = THIS_MODULE;

	spin_lock_init(&smd_tty[idx].reset_lock);

	spin_lock_init(&smd_tty[idx].ra_lock);

	spin_lock_init(&smd_tty[idx].reset_lock_lha2);

	spin_lock_init(&smd_tty[idx].ra_lock_lha3);

	smd_tty[idx].is_open = 0;

	setup_timer(&smd_tty[idx].buf_req_timer, buf_req_retry,

			(unsigned long)&smd_tty[idx]);