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Commit e63f9f74 authored by Jiri Slaby's avatar Jiri Slaby Committed by Greg Kroah-Hartman
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TTY: bfin_jtag_comm, use tty from tty_port 



Switch from mutex to tty_port->lock and to tty refcounting. This needs
a 'continue' to be added to re-grab a tty after schedule returns.

And since tty is not protected by bfin_jc_tty_mutex remove it as well.
But this needs tty_port->count to be protected by tty_port->lock now.

Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: uclinux-dist-devel@blackfin.uclinux.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 560460b8

drivers/tty/bfin_jtag_comm.c

+18 −18
Original line number Diff line number Diff line
@@ -62,8 +62,6 @@ static inline uint32_t bfin_write_emudat_chars(char a, char b, char c, char d) 


static struct tty_driver *bfin_jc_driver;

static struct task_struct *bfin_jc_kthread;

static struct tty_struct * volatile bfin_jc_tty;

static DEFINE_MUTEX(bfin_jc_tty_mutex);

static struct tty_port port;

static volatile struct circ_buf bfin_jc_write_buf;
@@ -73,18 +71,21 @@ bfin_jc_emudat_manager(void *arg) 
	uint32_t inbound_len = 0, outbound_len = 0;



	while (!kthread_should_stop()) {

		struct tty_struct *tty = tty_port_tty_get(&port);

		/* no one left to give data to, so sleep */

		if (bfin_jc_tty == NULL && circ_empty(&bfin_jc_write_buf)) {

		if (tty == NULL && circ_empty(&bfin_jc_write_buf)) {

			pr_debug("waiting for readers\n");

			__set_current_state(TASK_UNINTERRUPTIBLE);

			schedule();

			__set_current_state(TASK_RUNNING);

			continue;

		}



		/* no data available, so just chill */

		if (!(bfin_read_DBGSTAT() & EMUDIF) && circ_empty(&bfin_jc_write_buf)) {

			pr_debug("waiting for data (in_len = %i) (circ: %i %i)\n",

				inbound_len, bfin_jc_write_buf.tail, bfin_jc_write_buf.head);

			tty_kref_put(tty);

			if (inbound_len)

				schedule();

			else
@@ -94,9 +95,6 @@ bfin_jc_emudat_manager(void *arg) 


		/* if incoming data is ready, eat it */

		if (bfin_read_DBGSTAT() & EMUDIF) {

			struct tty_struct *tty;

			mutex_lock(&bfin_jc_tty_mutex);

			tty = (struct tty_struct *)bfin_jc_tty;

			if (tty != NULL) {

				uint32_t emudat = bfin_read_emudat();

				if (inbound_len == 0) {
@@ -110,7 +108,6 @@ bfin_jc_emudat_manager(void *arg) 
					tty_flip_buffer_push(tty);

				}

			}

			mutex_unlock(&bfin_jc_tty_mutex);

		}



		/* if outgoing data is ready, post it */
@@ -120,7 +117,6 @@ bfin_jc_emudat_manager(void *arg) 
				bfin_write_emudat(outbound_len);

				pr_debug("outgoing length: 0x%08x\n", outbound_len);

			} else {

				struct tty_struct *tty;

				int tail = bfin_jc_write_buf.tail;

				size_t ate = (4 <= outbound_len ? 4 : outbound_len);

				uint32_t emudat =
@@ -132,14 +128,12 @@ bfin_jc_emudat_manager(void *arg) 
				);

				bfin_jc_write_buf.tail += ate;

				outbound_len -= ate;

				mutex_lock(&bfin_jc_tty_mutex);

				tty = (struct tty_struct *)bfin_jc_tty;

				if (tty)

					tty_wakeup(tty);

				mutex_unlock(&bfin_jc_tty_mutex);

				pr_debug("  outgoing data: 0x%08x (pushing %zu)\n", emudat, ate);

			}

		}

		tty_kref_put(tty);

	}



	__set_current_state(TASK_RUNNING);
@@ -149,22 +143,28 @@ bfin_jc_emudat_manager(void *arg) 
static int

bfin_jc_open(struct tty_struct *tty, struct file *filp)

{

	mutex_lock(&bfin_jc_tty_mutex);

	unsigned long flags;



	spin_lock_irqsave(&port.lock, flags);

	port.count++;

	bfin_jc_tty = tty;

	spin_unlock_irqrestore(&port.lock, flags);

	tty_port_tty_set(&port, tty);

	wake_up_process(bfin_jc_kthread);

	mutex_unlock(&bfin_jc_tty_mutex);

	return 0;

}



static void

bfin_jc_close(struct tty_struct *tty, struct file *filp)

{

	mutex_lock(&bfin_jc_tty_mutex);

	if (--port.count == 0)

		bfin_jc_tty = NULL;

	unsigned long flags;

	bool last;



	spin_lock_irqsave(&port.lock, flags);

	last = --port.count == 0;

	spin_unlock_irqrestore(&port.lock, flags);

	if (last)

		tty_port_tty_set(&port, NULL);

	wake_up_process(bfin_jc_kthread);

	mutex_unlock(&bfin_jc_tty_mutex);

}



/* XXX: we dont handle the put_char() case where we must handle count = 1 */