From: Gaoyan <gao.yanB@h3c.com>
To: "paulus@samba.org" <paulus@samba.org>,
"davem@davemloft.net" <davem@davemloft.net>,
"kuba@kernel.org" <kuba@kernel.org>
Cc: "linux-ppp@vger.kernel.org" <linux-ppp@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: 答复: [PATCH] net: remove disc_data_lock in =?utf-8?Q?_ppp_line_discipl
Date: Thu, 31 Dec 2020 10:00:12 +0000 [thread overview]
Message-ID: <cfc4caad55554bf68bfae8a23c32950c@h3c.com> (raw)
In-Reply-To: <20201228071550.15745-1-gao.yanB@h3c.com>
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WARNING: multiple messages have this Message-ID (diff)
From: Gaoyan <gao.yanB@h3c.com>
To: "paulus@samba.org" <paulus@samba.org>,
"davem@davemloft.net" <davem@davemloft.net>,
"kuba@kernel.org" <kuba@kernel.org>
Cc: "linux-ppp@vger.kernel.org" <linux-ppp@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: 答复: [PATCH] net: remove disc_data_lock in ppp line discipline
Date: Thu, 31 Dec 2020 10:00:12 +0000 [thread overview]
Message-ID: <cfc4caad55554bf68bfae8a23c32950c@h3c.com> (raw)
In-Reply-To: <20201228071550.15745-1-gao.yanB@h3c.com>
Dear all：
Could I get your comments for the updates? If I can get a reply, it will help me a lot . Thanks
https://lkml.org/lkml/2020/12/28/19
*******************************
----Original mail -----
发件人: gaoyan (RD)
发送时间: 2020年12月28日 15:16
收件人: paulus@samba.org; davem@davemloft.net; kuba@kernel.org
抄送: linux-ppp@vger.kernel.org; netdev@vger.kernel.org; linux-kernel@vger.kernel.org; gaoyan (RD) <gao.yanB@h3c.com>
主题: [PATCH] net: remove disc_data_lock in ppp line discipline
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 prev parent reply other threads:[~2020-12-31 10:00 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-28 7:15 [PATCH] net: remove disc_data_lock in ppp line discipline Gao Yan
2020-12-28 7:15 ` Gao Yan
2020-12-31 10:00 ` Gaoyan [this message]
2020-12-31 10:00 ` 答复: " Gaoyan
2021-01-01 1:37 ` Xie He
2021-01-01 1:37 ` Xie He
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