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Date: Mon, 2 Apr 2012 13:54:20 +0200
From: Jiri Slaby <jslaby@...e.cz>
To: gregkh@...uxfoundation.org
Cc: alan@...ux.intel.com, linux-kernel@...r.kernel.org,
jirislaby@...il.com, Mike Frysinger <vapier@...too.org>,
uclinux-dist-devel@...ckfin.uclinux.org
Subject: [PATCH 36/69] 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: Jiri Slaby <jslaby@...e.cz>
Cc: Mike Frysinger <vapier@...too.org>
Cc: uclinux-dist-devel@...ckfin.uclinux.org
---
drivers/tty/bfin_jtag_comm.c | 36 ++++++++++++++++++------------------
1 file changed, 18 insertions(+), 18 deletions(-)
diff --git a/drivers/tty/bfin_jtag_comm.c b/drivers/tty/bfin_jtag_comm.c
index d81013c..61fc74f 100644
--- a/drivers/tty/bfin_jtag_comm.c
+++ b/drivers/tty/bfin_jtag_comm.c
@@ -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 */
--
1.7.9.2
--
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