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Subject[PATCH 1/3] tty: Combine SIGTTOU/SIGTTIN handling
Date
The job_control() check in n_tty_read() has nearly identical purpose
and results as tty_check_change(). Both functions' purpose is to
determine if the current task's pgrp is the foreground pgrp for the tty,
and if not, to signal the current pgrp.

Introduce __tty_check_change() which takes the signal to send
and performs the shared operations for job control() and
tty_check_change().

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
drivers/tty/n_tty.c | 26 ++------------------------
drivers/tty/tty_io.c | 46 ++++++++++++++++++++++++----------------------
include/linux/tty.h | 1 +
3 files changed, 27 insertions(+), 46 deletions(-)

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 20932cc..bd383c4 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2147,37 +2147,15 @@ extern ssize_t redirected_tty_write(struct file *, const char __user *,

static int job_control(struct tty_struct *tty, struct file *file)
{
- struct pid *pgrp;
-
/* Job control check -- must be done at start and after
every sleep (POSIX.1 7.1.1.4). */
/* NOTE: not yet done after every sleep pending a thorough
check of the logic of this change. -- jlc */
/* don't stop on /dev/console */
- if (file->f_op->write == redirected_tty_write ||
- current->signal->tty != tty)
+ if (file->f_op->write == redirected_tty_write)
return 0;

- rcu_read_lock();
- pgrp = task_pgrp(current);
-
- spin_lock_irq(&tty->ctrl_lock);
- if (!tty->pgrp)
- printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
- else if (pgrp != tty->pgrp) {
- spin_unlock_irq(&tty->ctrl_lock);
- if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned()) {
- rcu_read_unlock();
- return -EIO;
- }
- kill_pgrp(pgrp, SIGTTIN, 1);
- rcu_read_unlock();
- set_thread_flag(TIF_SIGPENDING);
- return -ERESTARTSYS;
- }
- spin_unlock_irq(&tty->ctrl_lock);
- rcu_read_unlock();
- return 0;
+ return __tty_check_change(tty, SIGTTIN);
}


diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 02785d8..eb210d7 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -390,10 +390,10 @@ EXPORT_SYMBOL_GPL(tty_find_polling_driver);
* Locking: ctrl_lock
*/

-int tty_check_change(struct tty_struct *tty)
+int __tty_check_change(struct tty_struct *tty, int sig)
{
unsigned long flags;
- struct pid *pgrp;
+ struct pid *pgrp, *tty_pgrp;
int ret = 0;

if (current->signal->tty != tty)
@@ -403,33 +403,35 @@ int tty_check_change(struct tty_struct *tty)
pgrp = task_pgrp(current);

spin_lock_irqsave(&tty->ctrl_lock, flags);
-
- if (!tty->pgrp) {
- printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
- goto out_unlock;
- }
- if (pgrp == tty->pgrp)
- goto out_unlock;
+ tty_pgrp = tty->pgrp;
spin_unlock_irqrestore(&tty->ctrl_lock, flags);

- if (is_ignored(SIGTTOU))
- goto out_rcuunlock;
- if (is_current_pgrp_orphaned()) {
- ret = -EIO;
- goto out_rcuunlock;
+ if (tty_pgrp && pgrp != tty->pgrp) {
+ if (is_ignored(sig)) {
+ if (sig == SIGTTIN)
+ ret = -EIO;
+ } else if (is_current_pgrp_orphaned())
+ ret = -EIO;
+ else {
+ kill_pgrp(pgrp, sig, 1);
+ set_thread_flag(TIF_SIGPENDING);
+ ret = -ERESTARTSYS;
+ }
}
- kill_pgrp(pgrp, SIGTTOU, 1);
- rcu_read_unlock();
- set_thread_flag(TIF_SIGPENDING);
- ret = -ERESTARTSYS;
- return ret;
-out_unlock:
- spin_unlock_irqrestore(&tty->ctrl_lock, flags);
-out_rcuunlock:
rcu_read_unlock();
+
+ if (!tty_pgrp) {
+ pr_warn("%s: tty_check_change: sig=%d, tty->pgrp == NULL!\n",
+ tty_name(tty), sig);
+ }
+
return ret;
}

+int tty_check_change(struct tty_struct *tty)
+{
+ return __tty_check_change(tty, SIGTTOU);
+}
EXPORT_SYMBOL(tty_check_change);

static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
diff --git a/include/linux/tty.h b/include/linux/tty.h
index c2889f4..533d7f6 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -423,6 +423,7 @@ extern int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
const char *routine);
extern const char *tty_name(const struct tty_struct *tty);
extern void tty_wait_until_sent(struct tty_struct *tty, long timeout);
+extern int __tty_check_change(struct tty_struct *tty, int sig);
extern int tty_check_change(struct tty_struct *tty);
extern void __stop_tty(struct tty_struct *tty);
extern void stop_tty(struct tty_struct *tty);
--
2.6.1


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