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tty: simplify calling of put_pid.

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This patch should contain no functional changes.

At some point I got confused and thought put_pid could not be called while a
spin lock was held.  While it may be nice to avoid that to reduce lock hold
times put_pid can be safely called while we hold a spin lock.

This patch removes all of the complications from the code introduced by my
misunderstanding, making the code a little more readable.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Eric W. Biederman 2007-05-08 00:26:53 -07:00 committed by Linus Torvalds
parent f67c3627b4
commit 2a65f1d9fe
1 changed files with 6 additions and 17 deletions
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23
drivers/char/tty_io.c
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@ -153,8 +153,7 @@ int tty_ioctl(struct inode * inode, struct file * file,
unsigned int cmd, unsigned long arg);
static int tty_fasync(int fd, struct file * filp, int on);
static void release_tty(struct tty_struct *tty, int idx);
static struct pid *__proc_set_tty(struct task_struct *tsk,
struct tty_struct *tty);
static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
/**
* alloc_tty_struct - allocate a tty object
@ -1532,10 +1531,9 @@ void disassociate_ctty(int on_exit)
}
spin_lock_irq(&current->sighand->siglock);
tty_pgrp = current->signal->tty_old_pgrp;
put_pid(current->signal->tty_old_pgrp);
current->signal->tty_old_pgrp = NULL;
spin_unlock_irq(&current->sighand->siglock);
put_pid(tty_pgrp);
mutex_lock(&tty_mutex);
/* It is possible that do_tty_hangup has free'd this tty */
@ -2506,7 +2504,6 @@ static int tty_open(struct inode * inode, struct file * filp)
int index;
dev_t device = inode->i_rdev;
unsigned short saved_flags = filp->f_flags;
struct pid *old_pgrp;
nonseekable_open(inode, filp);
@ -2600,17 +2597,15 @@ got_driver:
goto retry_open;
}
old_pgrp = NULL;
mutex_lock(&tty_mutex);
spin_lock_irq(&current->sighand->siglock);
if (!noctty &&
current->signal->leader &&
!current->signal->tty &&
tty->session == NULL)
old_pgrp = __proc_set_tty(current, tty);
__proc_set_tty(current, tty);
spin_unlock_irq(&current->sighand->siglock);
mutex_unlock(&tty_mutex);
put_pid(old_pgrp);
return 0;
}
@ -3835,9 +3830,8 @@ void proc_clear_tty(struct task_struct *p)
spin_unlock_irq(&p->sighand->siglock);
}
static struct pid *__proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
{
struct pid *old_pgrp;
if (tty) {
/* We should not have a session or pgrp to here but.... */
put_pid(tty->session);
@ -3845,21 +3839,16 @@ static struct pid *__proc_set_tty(struct task_struct *tsk, struct tty_struct *tt
tty->session = get_pid(task_session(tsk));
tty->pgrp = get_pid(task_pgrp(tsk));
}
old_pgrp = tsk->signal->tty_old_pgrp;
put_pid(tsk->signal->tty_old_pgrp);
tsk->signal->tty = tty;
tsk->signal->tty_old_pgrp = NULL;
return old_pgrp;
}
void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
{
struct pid *old_pgrp;
spin_lock_irq(&tsk->sighand->siglock);
old_pgrp = __proc_set_tty(tsk, tty);
__proc_set_tty(tsk, tty);
spin_unlock_irq(&tsk->sighand->siglock);
put_pid(old_pgrp);
}
struct tty_struct *get_current_tty(void)