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tty: n_tty: use guard()s

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Use guards in the n_tty code. This improves readability, makes error
handling easier, and marks locked portions of code explicit. All that
while being sure the lock is unlocked.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://patch.msgid.link/20251119100140.830761-3-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby (SUSE)
2025-11-19 11:01:32 +01:00
committed by Greg Kroah-Hartman
parent 977e75909d
commit 2fc541e525
1 changed files with 47 additions and 60 deletions
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107
drivers/tty/n_tty.c
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@@ -324,12 +324,9 @@ static void reset_buffer_flags(struct n_tty_data *ldata)
static void n_tty_packet_mode_flush(struct tty_struct *tty)
{
unsigned long flags;
if (tty->link->ctrl.packet) {
spin_lock_irqsave(&tty->ctrl.lock, flags);
tty->ctrl.pktstatus |= TIOCPKT_FLUSHREAD;
spin_unlock_irqrestore(&tty->ctrl.lock, flags);
scoped_guard(spinlock_irqsave, &tty->ctrl.lock)
tty->ctrl.pktstatus |= TIOCPKT_FLUSHREAD;
wake_up_interruptible(&tty->link->read_wait);
}
}
@@ -349,13 +346,12 @@ static void n_tty_packet_mode_flush(struct tty_struct *tty)
*/
static void n_tty_flush_buffer(struct tty_struct *tty)
{
down_write(&tty->termios_rwsem);
guard(rwsem_write)(&tty->termios_rwsem);
reset_buffer_flags(tty->disc_data);
n_tty_kick_worker(tty);
if (tty->link)
n_tty_packet_mode_flush(tty);
up_write(&tty->termios_rwsem);
}
/**
@@ -737,25 +733,23 @@ static void commit_echoes(struct tty_struct *tty)
size_t nr, old, echoed;
size_t head;
mutex_lock(&ldata->output_lock);
head = ldata->echo_head;
ldata->echo_mark = head;
old = ldata->echo_commit - ldata->echo_tail;
scoped_guard(mutex, &ldata->output_lock) {
head = ldata->echo_head;
ldata->echo_mark = head;
old = ldata->echo_commit - ldata->echo_tail;
/* Process committed echoes if the accumulated # of bytes
* is over the threshold (and try again each time another
* block is accumulated) */
nr = head - ldata->echo_tail;
if (nr < ECHO_COMMIT_WATERMARK ||
(nr % ECHO_BLOCK > old % ECHO_BLOCK)) {
mutex_unlock(&ldata->output_lock);
return;
/*
* Process committed echoes if the accumulated # of bytes is over the threshold
* (and try again each time another block is accumulated)
*/
nr = head - ldata->echo_tail;
if (nr < ECHO_COMMIT_WATERMARK || (nr % ECHO_BLOCK > old % ECHO_BLOCK))
return;
ldata->echo_commit = head;
echoed = __process_echoes(tty);
}
ldata->echo_commit = head;
echoed = __process_echoes(tty);
mutex_unlock(&ldata->output_lock);
if (echoed && tty->ops->flush_chars)
tty->ops->flush_chars(tty);
}
@@ -768,10 +762,10 @@ static void process_echoes(struct tty_struct *tty)
if (ldata->echo_mark == ldata->echo_tail)
return;
mutex_lock(&ldata->output_lock);
ldata->echo_commit = ldata->echo_mark;
echoed = __process_echoes(tty);
mutex_unlock(&ldata->output_lock);
scoped_guard(mutex, &ldata->output_lock) {
ldata->echo_commit = ldata->echo_mark;
echoed = __process_echoes(tty);
}
if (echoed && tty->ops->flush_chars)
tty->ops->flush_chars(tty);
@@ -786,10 +780,9 @@ static void flush_echoes(struct tty_struct *tty)
ldata->echo_commit == ldata->echo_head)
return;
mutex_lock(&ldata->output_lock);
guard(mutex)(&ldata->output_lock);
ldata->echo_commit = ldata->echo_head;
__process_echoes(tty);
mutex_unlock(&ldata->output_lock);
}
/**
@@ -1078,18 +1071,19 @@ static void isig(int sig, struct tty_struct *tty)
if (L_NOFLSH(tty)) {
/* signal only */
__isig(sig, tty);
return;
}
} else { /* signal and flush */
up_read(&tty->termios_rwsem);
down_write(&tty->termios_rwsem);
/* signal and flush */
up_read(&tty->termios_rwsem);
scoped_guard(rwsem_write, &tty->termios_rwsem) {
__isig(sig, tty);
/* clear echo buffer */
mutex_lock(&ldata->output_lock);
ldata->echo_head = ldata->echo_tail = 0;
ldata->echo_mark = ldata->echo_commit = 0;
mutex_unlock(&ldata->output_lock);
scoped_guard(mutex, &ldata->output_lock) {
ldata->echo_head = ldata->echo_tail = 0;
ldata->echo_mark = ldata->echo_commit = 0;
}
/* clear output buffer */
tty_driver_flush_buffer(tty);
@@ -1100,10 +1094,8 @@ static void isig(int sig, struct tty_struct *tty)
/* notify pty master of flush */
if (tty->link)
n_tty_packet_mode_flush(tty);
up_write(&tty->termios_rwsem);
down_read(&tty->termios_rwsem);
}
down_read(&tty->termios_rwsem);
}
/**
@@ -1683,7 +1675,7 @@ n_tty_receive_buf_common(struct tty_struct *tty, const u8 *cp, const u8 *fp,
size_t n, rcvd = 0;
int room, overflow;
down_read(&tty->termios_rwsem);
guard(rwsem_read)(&tty->termios_rwsem);
do {
/*
@@ -1752,8 +1744,6 @@ n_tty_receive_buf_common(struct tty_struct *tty, const u8 *cp, const u8 *fp,
n_tty_kick_worker(tty);
}
up_read(&tty->termios_rwsem);
return rcvd;
}
@@ -1879,10 +1869,9 @@ static void n_tty_close(struct tty_struct *tty)
if (tty->link)
n_tty_packet_mode_flush(tty);
down_write(&tty->termios_rwsem);
guard(rwsem_write)(&tty->termios_rwsem);
vfree(ldata);
tty->disc_data = NULL;
up_write(&tty->termios_rwsem);
}
/**
@@ -2247,10 +2236,10 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, u8 *kbuf,
u8 cs;
if (kb != kbuf)
break;
spin_lock_irq(&tty->link->ctrl.lock);
cs = tty->link->ctrl.pktstatus;
tty->link->ctrl.pktstatus = 0;
spin_unlock_irq(&tty->link->ctrl.lock);
scoped_guard(spinlock_irq, &tty->link->ctrl.lock) {
cs = tty->link->ctrl.pktstatus;
tty->link->ctrl.pktstatus = 0;
}
*kb++ = cs;
nr--;
break;
@@ -2357,7 +2346,7 @@ static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
return retval;
}
down_read(&tty->termios_rwsem);
guard(rwsem_read)(&tty->termios_rwsem);
/* Write out any echoed characters that are still pending */
process_echoes(tty);
@@ -2395,9 +2384,8 @@ static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
struct n_tty_data *ldata = tty->disc_data;
while (nr > 0) {
mutex_lock(&ldata->output_lock);
num = tty->ops->write(tty, b, nr);
mutex_unlock(&ldata->output_lock);
scoped_guard(mutex, &ldata->output_lock)
num = tty->ops->write(tty, b, nr);
if (num < 0) {
retval = num;
goto break_out;
@@ -2424,7 +2412,7 @@ break_out:
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;
}
@@ -2498,12 +2486,11 @@ static int n_tty_ioctl(struct tty_struct *tty, unsigned int cmd,
case TIOCOUTQ:
return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
case TIOCINQ:
down_write(&tty->termios_rwsem);
if (L_ICANON(tty) && !L_EXTPROC(tty))
num = inq_canon(ldata);
else
num = read_cnt(ldata);
up_write(&tty->termios_rwsem);
scoped_guard(rwsem_write, &tty->termios_rwsem)
if (L_ICANON(tty) && !L_EXTPROC(tty))
num = inq_canon(ldata);
else
num = read_cnt(ldata);
return put_user(num, (unsigned int __user *) arg);
default:
return n_tty_ioctl_helper(tty, cmd, arg);