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

Gao Yan
2021-01-01T03:50:33Z

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.yanB@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