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authorArnd Bergmann <arnd@arndb.de>2010-06-01 22:53:07 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2010-08-10 22:47:43 +0200
commit203652192634c1fce5e79df0a8ff2fabfaefd3ab (patch)
tree9c2ee78c04b0750220fa34e7adc541c16bf21e90 /drivers/char/amiserial.c
parenttty: reorder ldisc locking (diff)
downloadlinux-203652192634c1fce5e79df0a8ff2fabfaefd3ab.tar.xz
linux-203652192634c1fce5e79df0a8ff2fabfaefd3ab.zip
tty: untangle locking of wait_until_sent
Some wait_until_sent versions require the big tty mutex, others don't and some callers of wait_until_sent already hold it while other don't. That leads to recursive use of the BTM in these functions, which we're trying to get rid of. This turns all cleans up the locking there so that the driver's wait_until_sent function never takes the BTM itself if it is already called with that lock held. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/char/amiserial.c')
-rw-r--r--drivers/char/amiserial.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/char/amiserial.c b/drivers/char/amiserial.c
index 1b21a7adeb58..8228e61bb54d 100644
--- a/drivers/char/amiserial.c
+++ b/drivers/char/amiserial.c
@@ -1528,6 +1528,7 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
{
struct async_struct * info = tty->driver_data;
unsigned long orig_jiffies, char_time;
+ int tty_was_locked = tty_locked();
int lsr;
if (serial_paranoia_check(info, tty->name, "rs_wait_until_sent"))
@@ -1538,7 +1539,12 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
orig_jiffies = jiffies;
- tty_lock_nested(); /* tty_wait_until_sent is called from lots of places */
+ /*
+ * tty_wait_until_sent is called from lots of places,
+ * with or without the BTM.
+ */
+ if (!tty_was_locked)
+ tty_lock();
/*
* Set the check interval to be 1/5 of the estimated time to
* send a single character, and make it at least 1. The check
@@ -1579,7 +1585,8 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
break;
}
__set_current_state(TASK_RUNNING);
- tty_unlock();
+ if (!tty_was_locked)
+ tty_unlock();
#ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
printk("lsr = %d (jiff=%lu)...done\n", lsr, jiffies);
#endif