From: Gao Yan <gao.yanB@h3c.com>
To: <paulus@samba.org>, <davem@davemloft.net>, <kuba@kernel.org>
Cc: <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
Gao Yan <gao.yanB@h3c.com>
Subject: [PATCH] net: remove disc_data_lock in ppp line discipline
Date: Tue, 15 Dec 2020 23:00:54 +0800 [thread overview]
Message-ID: <20201215150054.570-1-gao.yanB@h3c.com> (raw)
tty layer provide tty->ldisc_sem lock to protect tty->disc_data;
For examlpe, when cpu A is running ppp_synctty_ioctl that
hold the tty->ldisc_sem, so if cpu B calls ppp_synctty_close,
it will wait until cpu A release tty->ldisc_sem. So I think it is
unnecessary to have the disc_data_lock;
cpu A cpu B
tty_ioctl tty_reopen
->hold tty->ldisc_sem ->hold tty->ldisc_sem(write), failed
->ld->ops->ioctl ->wait...
->release tty->ldisc_sem ->wait...OK,hold tty->ldisc_sem
->tty_ldisc_reinit
->tty_ldisc_close
->ld->ops->close
Signed-off-by: Gao Yan <gao.yanB@h3c.com>
---
drivers/net/ppp/ppp_async.c | 5 -----
drivers/net/ppp/ppp_synctty.c | 5 -----
2 files changed, 10 deletions(-)
diff --git a/drivers/net/ppp/ppp_async.c b/drivers/net/ppp/ppp_async.c
index 29a0917a8..f8cb591d6 100644
--- a/drivers/net/ppp/ppp_async.c
+++ b/drivers/net/ppp/ppp_async.c
@@ -127,17 +127,14 @@ 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;
- read_lock(&disc_data_lock);
ap = tty->disc_data;
if (ap != NULL)
refcount_inc(&ap->refcnt);
- read_unlock(&disc_data_lock);
return ap;
}
@@ -216,10 +213,8 @@ ppp_asynctty_close(struct tty_struct *tty)
{
struct asyncppp *ap;
- 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..8cdf7268c 100644
--- a/drivers/net/ppp/ppp_synctty.c
+++ b/drivers/net/ppp/ppp_synctty.c
@@ -129,17 +129,14 @@ 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;
- read_lock(&disc_data_lock);
ap = tty->disc_data;
if (ap != NULL)
refcount_inc(&ap->refcnt);
- read_unlock(&disc_data_lock);
return ap;
}
@@ -215,10 +212,8 @@ ppp_sync_close(struct tty_struct *tty)
{
struct syncppp *ap;
- 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
next reply other threads:[~2020-12-15 15:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-15 15:00 Gao Yan [this message]
2020-12-17 0:48 ` [PATCH] net: remove disc_data_lock in ppp line discipline Jakub Kicinski
2020-12-28 7:15 Gao Yan
2021-01-01 1:37 ` Xie He
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