From: Jiri Slaby <jslaby@suse.cz>
To: gregkh@linuxfoundation.org
Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
Jiri Slaby <jslaby@suse.cz>
Subject: [PATCH 17/35] tty: drop tty_ldisc_ops::refcount
Date: Wed, 5 May 2021 11:19:10 +0200 [thread overview]
Message-ID: <20210505091928.22010-18-jslaby@suse.cz> (raw)
In-Reply-To: <20210505091928.22010-1-jslaby@suse.cz>
The refcount is checked only in tty_unregister_ldisc and EBUSY returned
if it is nonzero. But none of the tty_unregister_ldisc callers act
anyhow if this (or any other) error is returned. So remove
tty_ldisc_ops::refcount completely and make tty_unregister_ldisc return
'void' in the next patches. That means we assume tty_unregister_ldisc is
not called while the ldisc might be in use. That relies on
try_module_get in get_ldops and module_put in put_ldops.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
drivers/tty/n_tty.c | 2 +-
drivers/tty/tty_ldisc.c | 14 +++-----------
include/linux/tty_ldisc.h | 2 --
3 files changed, 4 insertions(+), 14 deletions(-)
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 2fe27905c398..0ec93f1a61f5 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2450,7 +2450,7 @@ void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
{
*ops = n_tty_ops;
ops->owner = NULL;
- ops->refcount = ops->flags = 0;
+ ops->flags = 0;
}
EXPORT_SYMBOL_GPL(n_tty_inherit_ops);
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index d02deeb5e584..98e8316fd28a 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -69,7 +69,6 @@ int tty_register_ldisc(struct tty_ldisc_ops *new_ldisc)
raw_spin_lock_irqsave(&tty_ldiscs_lock, flags);
tty_ldiscs[new_ldisc->num] = new_ldisc;
- new_ldisc->refcount = 0;
raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags);
return ret;
@@ -90,16 +89,12 @@ EXPORT_SYMBOL(tty_register_ldisc);
int tty_unregister_ldisc(struct tty_ldisc_ops *ldisc)
{
unsigned long flags;
- int ret = 0;
raw_spin_lock_irqsave(&tty_ldiscs_lock, flags);
- if (tty_ldiscs[ldisc->num]->refcount)
- ret = -EBUSY;
- else
- tty_ldiscs[ldisc->num] = NULL;
+ tty_ldiscs[ldisc->num] = NULL;
raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags);
- return ret;
+ return 0;
}
EXPORT_SYMBOL(tty_unregister_ldisc);
@@ -113,10 +108,8 @@ static struct tty_ldisc_ops *get_ldops(int disc)
ldops = tty_ldiscs[disc];
if (ldops) {
ret = ERR_PTR(-EAGAIN);
- if (try_module_get(ldops->owner)) {
- ldops->refcount++;
+ if (try_module_get(ldops->owner))
ret = ldops;
- }
}
raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags);
return ret;
@@ -127,7 +120,6 @@ static void put_ldops(struct tty_ldisc_ops *ldops)
unsigned long flags;
raw_spin_lock_irqsave(&tty_ldiscs_lock, flags);
- ldops->refcount--;
module_put(ldops->owner);
raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags);
}
diff --git a/include/linux/tty_ldisc.h b/include/linux/tty_ldisc.h
index c20ca6a75b4c..fbe9de278629 100644
--- a/include/linux/tty_ldisc.h
+++ b/include/linux/tty_ldisc.h
@@ -208,8 +208,6 @@ struct tty_ldisc_ops {
const char *fp, int count);
struct module *owner;
-
- int refcount;
};
struct tty_ldisc {
--
2.31.1
next prev parent reply other threads:[~2021-05-05 9:20 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-05 9:18 [PATCH 00/35] tty cleanup for 5.14 Jiri Slaby
2021-05-05 9:18 ` [PATCH 01/35] tty: remove broken r3964 line discipline Jiri Slaby
2021-05-05 9:26 ` Greg KH
2021-05-05 9:18 ` [PATCH 02/35] n_tty: remove n_tty_receive_char wrapper Jiri Slaby
2021-05-05 9:18 ` [PATCH 03/35] n_tty: remove n_tty_receive_char_fast Jiri Slaby
2021-05-05 9:18 ` [PATCH 04/35] n_tty: drop n_tty_receive_buf_fast Jiri Slaby
2021-05-05 9:18 ` [PATCH 05/35] n_tty: drop parmrk_dbl from n_tty_receive_char Jiri Slaby
2021-05-05 9:18 ` [PATCH 06/35] n_tty: move lnext handling Jiri Slaby
2021-05-05 9:19 ` [PATCH 07/35] n_tty: make n_tty_receive_char_special return void Jiri Slaby
2021-05-05 9:19 ` [PATCH 08/35] n_tty: do only one cp dereference in n_tty_receive_buf_standard Jiri Slaby
2021-05-05 9:19 ` [PATCH 09/35] n_tty: invert TTY_NORMAL condition " Jiri Slaby
2021-05-05 9:19 ` [PATCH 10/35] n_tty: remove superfluous return from n_tty_receive_signal_char Jiri Slaby
2021-05-05 9:19 ` [PATCH 11/35] tty: make fp of tty_ldisc_ops::receive_buf{,2} const Jiri Slaby
2021-05-05 9:19 ` [PATCH 12/35] tty: cumulate and document tty_struct::flow* members Jiri Slaby
2021-05-05 9:19 ` [PATCH 13/35] tty: cumulate and document tty_struct::ctrl* members Jiri Slaby
2021-05-05 9:19 ` [PATCH 14/35] tty: set tty_ldisc_ops::num statically Jiri Slaby
2021-05-05 9:19 ` [PATCH 15/35] n_gsm: use goto-failpaths in gsm_init Jiri Slaby
2021-05-05 9:19 ` [PATCH 16/35] tty: make tty_ldisc_ops a param in tty_unregister_ldisc Jiri Slaby
2021-05-05 9:19 ` Jiri Slaby [this message]
2021-05-05 9:19 ` [PATCH 18/35] tty: no checking of tty_unregister_ldisc Jiri Slaby
2021-05-05 9:19 ` [PATCH 19/35] tty: return void from tty_unregister_ldisc Jiri Slaby
2021-05-05 9:19 ` [PATCH 20/35] ti-st: use goto-failpath in st_core_init Jiri Slaby
2021-05-05 9:19 ` [PATCH 21/35] ti-st: use tty_write_room Jiri Slaby
2021-05-05 9:19 ` [PATCH 22/35] tty: make tty_operations::write_room return uint Jiri Slaby
2021-05-05 9:25 ` Geert Uytterhoeven
2021-05-05 10:34 ` Anton Ivanov
2021-05-05 10:43 ` David Sterba
2021-05-05 11:53 ` Max Filippov
2021-05-05 12:15 ` Alex Elder
2021-05-10 11:27 ` Laurentiu Tudor
2021-05-05 9:19 ` [PATCH 23/35] USB: serial: make usb_serial_driver::write_room " Jiri Slaby
2021-05-19 9:07 ` Johan Hovold
2021-05-05 9:19 ` [PATCH 24/35] tty: make tty_buffer_space_avail " Jiri Slaby
2021-05-05 9:19 ` [PATCH 25/35] tty: remove tty_operations::chars_in_buffer for non-buffering Jiri Slaby
2021-05-05 11:51 ` Max Filippov
2021-05-06 5:47 ` Jiri Slaby
2021-05-06 5:56 ` Greg KH
2021-05-05 9:19 ` [PATCH 26/35] tty: make tty_operations::chars_in_buffer return uint Jiri Slaby
2021-05-05 10:34 ` Anton Ivanov
2021-05-05 10:43 ` David Sterba
2021-05-05 9:19 ` [PATCH 27/35] serial: make usb_serial_driver::chars_in_buffer " Jiri Slaby
2021-05-19 9:09 ` Johan Hovold
2021-05-05 9:19 ` [PATCH 28/35] nozomi: simplify ntty_chars_in_buffer Jiri Slaby
2021-05-05 9:19 ` [PATCH 29/35] USB: serial: digi_acceleport, simplify digi_chars_in_buffer Jiri Slaby
2021-05-19 9:11 ` Johan Hovold
2021-05-05 9:19 ` [PATCH 30/35] tty: remove empty tty_operations::flush_buffer Jiri Slaby
2021-05-05 9:19 ` [PATCH 31/35] tty: remove empty tty_operations::set_termios Jiri Slaby
2021-05-05 10:34 ` Anton Ivanov
2021-05-05 9:19 ` [PATCH 32/35] isdn: capi, remove optional tty ops Jiri Slaby
2021-05-05 9:19 ` [PATCH 33/35] isdn: capi, drop useless pr_debugs Jiri Slaby
2021-05-05 9:19 ` [PATCH 34/35] tty: make tty_get_byte_size available Jiri Slaby
2021-05-06 7:16 ` Joe Perches
2021-05-06 7:19 ` Jiri Slaby
[not found] ` <CAHp75Vfq6ABW7ukwaKmZOF2DszmuHD28S=wcLcFowvRdXTnWmg@mail.gmail.com>
2021-05-06 8:31 ` Jiri Slaby
2021-05-06 9:33 ` Andy Shevchenko
2021-05-06 8:35 ` Joe Perches
2021-05-10 7:00 ` [PATCH v2 " Jiri Slaby
2021-05-10 9:47 ` Johan Hovold
2021-05-13 7:24 ` Jiri Slaby
2021-05-13 9:41 ` Johan Hovold
2021-05-05 9:19 ` [PATCH 35/35] tty: make use of tty_get_byte_size Jiri Slaby
2021-05-10 9:59 ` Johan Hovold
2021-05-13 15:04 ` [PATCH 00/35] tty cleanup for 5.14 Greg KH
2021-05-13 16:20 ` Johan Hovold
2021-05-13 16:29 ` Greg KH
2021-05-14 8:11 ` Johan Hovold
2021-06-10 9:02 ` [PATCH v3 1/4] tty: make tty_get_{char,frame}_size available Jiri Slaby
2021-06-10 9:02 ` [PATCH v3 2/4] mxs-auart: redefine AUART_LINECTRL_WLEN to accept bits count Jiri Slaby
2021-06-10 9:02 ` [PATCH v3 3/4] cypress_m8: switch data_bits to real character bits Jiri Slaby
2021-06-10 9:02 ` [PATCH v3 4/4] tty: make use of tty_get_{char,frame}_size Jiri Slaby
2021-06-10 15:15 ` Alex Elder
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