From: Gao Yan <gao.yanB@h3c.com>
To: paulus@samba.org, davem@davemloft.net, kuba@kernel.org
Cc: linux-ppp@vger.kernel.org, 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: Mon, 28 Dec 2020 07:15:50 +0000 [thread overview]
Message-ID: <20201228071550.15745-1-gao.yanB@h3c.com> (raw)
In tty layer, it use tty->ldisc_sem to proect tty_ldisc_ops.
So I think tty->ldisc_sem can also protect tty->disc_data;
For examlpe,
When cpu A is running ppp_synctty_ioctl that hold the tty->ldisc_sem,
at the same time 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 | 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
next reply other threads:[~2020-12-28 7:15 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-28 7:15 Gao Yan [this message]
2020-12-31 10:00 ` 答复: [PATCH] net: remove disc_data_lock in =?utf-8?Q?_ppp_line_discipl Gaoyan
2021-01-01 1:37 ` [PATCH] net: remove disc_data_lock in ppp line discipline Xie He
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