[PATCH] [v2]net:ppp: remove disc_data_lock in ppp line discipline

[Gao Yan]

In tty layer, it provides tty->ldisc_sem to protect all tty_ldisc_ops
including ppp_sync_ldisc. So I think tty->ldisc_sem can also
protect tty->disc_data, and the disc_data_lock is not necessary.

Signed-off-by: Gao Yan <gao.y...@h3c.com>
---
 drivers/net/ppp/ppp_async.c   | 11 ++---------
 drivers/net/ppp/ppp_synctty.c | 12 ++----------
 2 files changed, 4 insertions(+), 19 deletions(-)

diff --git a/drivers/net/ppp/ppp_async.c b/drivers/net/ppp/ppp_async.c
index 29a0917a8..20b50facd 100644
--- a/drivers/net/ppp/ppp_async.c
+++ b/drivers/net/ppp/ppp_async.c
@@ -127,17 +127,13 @@ static const struct ppp_channel_ops async_ops = {
  * FIXME: this is no longer true. The _close path for the ldisc is
  * now guaranteed to be sane.
  */
-static DEFINE_RWLOCK(disc_data_lock);
 
 static struct asyncppp *ap_get(struct tty_struct *tty)
 {
-       struct asyncppp *ap;
+       struct asyncppp *ap = tty->disc_data;
 
-       read_lock(&disc_data_lock);
-       ap = tty->disc_data;
        if (ap != NULL)
                refcount_inc(&ap->refcnt);
-       read_unlock(&disc_data_lock);
        return ap;
 }
 
@@ -214,12 +210,9 @@ ppp_asynctty_open(struct tty_struct *tty)
 static void
 ppp_asynctty_close(struct tty_struct *tty)
 {
-       struct asyncppp *ap;
+       struct asyncppp *ap = tty->disc_data;
 
-       write_lock_irq(&disc_data_lock);
-       ap = tty->disc_data;
        tty->disc_data = NULL;
-       write_unlock_irq(&disc_data_lock);
        if (!ap)
                return;
 
diff --git a/drivers/net/ppp/ppp_synctty.c b/drivers/net/ppp/ppp_synctty.c
index 0f338752c..53fb68e29 100644
--- a/drivers/net/ppp/ppp_synctty.c
+++ b/drivers/net/ppp/ppp_synctty.c
@@ -129,17 +129,12 @@ ppp_print_buffer (const char *name, const __u8 *buf, int 
count)
  *
  * FIXME: Fixed in tty_io nowadays.
  */
-static DEFINE_RWLOCK(disc_data_lock);
-
 static struct syncppp *sp_get(struct tty_struct *tty)
 {
-       struct syncppp *ap;
+       struct syncppp *ap = tty->disc_data;
 
-       read_lock(&disc_data_lock);
-       ap = tty->disc_data;
        if (ap != NULL)
                refcount_inc(&ap->refcnt);
-       read_unlock(&disc_data_lock);
        return ap;
 }
 
@@ -213,12 +208,9 @@ ppp_sync_open(struct tty_struct *tty)
 static void
 ppp_sync_close(struct tty_struct *tty)
 {
-       struct syncppp *ap;
+       struct syncppp *ap = tty->disc_data;
 
-       write_lock_irq(&disc_data_lock);
-       ap = tty->disc_data;
        tty->disc_data = NULL;
-       write_unlock_irq(&disc_data_lock);
        if (!ap)
                return;
 
-- 
2.17.1