| Message ID | 20201215150054.570-1-gao.yanB@h3c.com (mailing list archive) |
|---|---|
| State | Deferred |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: remove disc_data_lock in ppp line discipline | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Guessed tree name to be net-next |
| netdev/subject_prefix | warning | Target tree name not specified in the subject |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 45 this patch: 45 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 54 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 35 this patch: 35 |
| netdev/header_inline | success | Link |
| netdev/stable | success | Stable not CCed |
On Tue, 15 Dec 2020 23:00:54 +0800 Gao Yan wrote: > 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> # Form letter - net-next is closed We have already sent the networking pull request for 5.11 and therefore net-next is closed for new drivers, features, code refactoring and optimizations. We are currently accepting bug fixes only. Please repost when net-next reopens after 5.11-rc1 is cut. Look out for the announcement on the mailing list or check: http://vger.kernel.org/~davem/net-next.html RFC patches sent for review only are obviously welcome at any time.
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;
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(-)