From: Arseny Maslennikov <ar@cs.msu.ru>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.com>,
linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Arseny Maslennikov <ar@cs.msu.ru>, Rob Landley <rob@landley.net>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Pavel Machek <pavel@ucw.cz>,
linux-api@vger.kernel.org,
"Vladimir D. Seleznev" <vseleznv@altlinux.org>
Subject: [PATCH v3 6/7] n_tty: ->ops->write: Cut core logic out to a separate function
Date: Thu, 30 Apr 2020 09:43:00 +0300 [thread overview]
Message-ID: <20200430064301.1099452-7-ar@cs.msu.ru> (raw)
In-Reply-To: <20200430064301.1099452-1-ar@cs.msu.ru>
To simplify internal re-use of the line discipline's write method,
we isolate the work it does to its own function.
Since in-kernel callers might not refer to the tty through a file,
the struct file* argument might make no sense, so we also stop
tty_io_nonblock() from dereferencing file too early, allowing
to pass NULL as the referring file here.
Signed-off-by: Arseny Maslennikov <ar@cs.msu.ru>
---
drivers/tty/n_tty.c | 33 ++++++++++++++++++++++-----------
include/linux/tty.h | 2 +-
2 files changed, 23 insertions(+), 12 deletions(-)
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 10d6b60a5..f72a3fd4b 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2309,22 +2309,15 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
* lock themselves)
*/
-static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
- const unsigned char *buf, size_t nr)
+static ssize_t do_n_tty_write(struct tty_struct *tty, struct file *file,
+ const unsigned char *buf, size_t nr)
{
const unsigned char *b = buf;
DEFINE_WAIT_FUNC(wait, woken_wake_function);
int c;
ssize_t retval = 0;
- /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
- if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
- retval = tty_check_change(tty);
- if (retval)
- return retval;
- }
-
- down_read(&tty->termios_rwsem);
+ lockdep_assert_held_read(&tty->termios_rwsem);
/* Write out any echoed characters that are still pending */
process_echoes(tty);
@@ -2392,10 +2385,28 @@ static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
remove_wait_queue(&tty->write_wait, &wait);
if (nr && tty->fasync)
set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
- up_read(&tty->termios_rwsem);
return (b - buf) ? b - buf : retval;
}
+static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
+ const unsigned char *buf, size_t nr)
+{
+ ssize_t retval = 0;
+
+ /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
+ if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
+ retval = tty_check_change(tty);
+ if (retval)
+ return retval;
+ }
+
+ down_read(&tty->termios_rwsem);
+ retval = do_n_tty_write(tty, file, buf, nr);
+ up_read(&tty->termios_rwsem);
+
+ return retval;
+}
+
/**
* n_tty_poll - poll method for N_TTY
* @tty: terminal device
diff --git a/include/linux/tty.h b/include/linux/tty.h
index cafb9b7f7..3499845ab 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -390,7 +390,7 @@ static inline void tty_set_flow_change(struct tty_struct *tty, int val)
static inline bool tty_io_nonblock(struct tty_struct *tty, struct file *file)
{
- return file->f_flags & O_NONBLOCK ||
+ return (file && file->f_flags & O_NONBLOCK) ||
test_bit(TTY_LDISC_CHANGING, &tty->flags);
}
--
2.26.2
next prev parent reply other threads:[~2020-04-30 7:17 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-30 6:42 [PATCH v3 0/7] TTY Keyboard Status Request Arseny Maslennikov
2020-04-30 6:42 ` [PATCH v3 1/7] signal.h: Define SIGINFO on all architectures Arseny Maslennikov
2020-04-30 6:42 ` [PATCH v3 2/7] tty: termios: Reserve space for VSTATUS in .c_cc Arseny Maslennikov
2020-04-30 6:42 ` [PATCH v3 3/7] n_tty: Send SIGINFO to fg pgrp on status request character Arseny Maslennikov
2020-04-30 6:42 ` [PATCH v3 4/7] linux/signal.h: Ignore SIGINFO by default in new tasks Arseny Maslennikov
2020-04-30 6:53 ` Jiri Slaby
2020-04-30 7:14 ` Christian Brauner
2020-04-30 7:19 ` Greg Kroah-Hartman
2020-04-30 7:37 ` Aleksa Sarai
2020-04-30 8:00 ` Christian Brauner
2020-04-30 6:42 ` [PATCH v3 5/7] tty: Add NOKERNINFO lflag to termios Arseny Maslennikov
2020-04-30 6:55 ` Jiri Slaby
2020-04-30 7:20 ` Arseny Maslennikov
2020-04-30 6:43 ` Arseny Maslennikov [this message]
2020-04-30 6:43 ` [PATCH v3 7/7] n_tty: Provide an informational line on VSTATUS receipt Arseny Maslennikov
2020-04-30 7:29 ` Jiri Slaby
2020-04-30 9:08 ` Arseny Maslennikov
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