[PATCH] pid: replace is_orphaned_pgrp with is_current_pgrp_orphaned
Every call to is_orphaned_pgrp passed in process_group(current) which is racy
with respect to another thread changing our process group. It didn't bite us
because we were dealing with integers and the worse we would get would be a
stale answer.
In switching the checks to use struct pid to be a little more efficient and
prepare the way for pid namespaces this race became apparent.
So I simplified the calls to the more specialized is_current_pgrp_orphaned so
I didn't have to worry about making logic changes to avoid the race.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c
index 2bdb014..c035c2f 100644
--- a/drivers/char/n_tty.c
+++ b/drivers/char/n_tty.c
@@ -1188,7 +1188,7 @@
printk("read_chan: tty->pgrp <= 0!\n");
else if (process_group(current) != tty->pgrp) {
if (is_ignored(SIGTTIN) ||
- is_orphaned_pgrp(process_group(current)))
+ is_current_pgrp_orphaned())
return -EIO;
kill_pg(process_group(current), SIGTTIN, 1);
return -ERESTARTSYS;
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 95f3596..94070f7 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1118,7 +1118,7 @@
return 0;
if (is_ignored(SIGTTOU))
return 0;
- if (is_orphaned_pgrp(process_group(current)))
+ if (is_current_pgrp_orphaned())
return -EIO;
(void) kill_pg(process_group(current), SIGTTOU, 1);
return -ERESTARTSYS;
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 0a10a4e..d0e03c4 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -303,7 +303,7 @@
int buflen);
extern void tty_write_message(struct tty_struct *tty, char *msg);
-extern int is_orphaned_pgrp(int pgrp);
+extern int is_current_pgrp_orphaned(void);
extern int is_ignored(int sig);
extern int tty_signal(int sig, struct tty_struct *tty);
extern void tty_hangup(struct tty_struct * tty);
diff --git a/kernel/exit.c b/kernel/exit.c
index 407b80a..f132349 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -229,12 +229,12 @@
return ret; /* (sighing) "Often!" */
}
-int is_orphaned_pgrp(int pgrp)
+int is_current_pgrp_orphaned(void)
{
int retval;
read_lock(&tasklist_lock);
- retval = will_become_orphaned_pgrp(find_pid(pgrp), NULL);
+ retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
read_unlock(&tasklist_lock);
return retval;
diff --git a/kernel/signal.c b/kernel/signal.c
index de66def..a9b679e 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1909,7 +1909,7 @@
/* signals can be posted during this window */
- if (is_orphaned_pgrp(process_group(current)))
+ if (is_current_pgrp_orphaned())
goto relock;
spin_lock_irq(¤t->sighand->siglock);
