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authorEric W. Biederman <ebiederm@xmission.com>2007-02-12 00:52:56 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-02-12 09:48:31 -0800
commit04a2e6a5cbf84e85fe86de0a18f6509b147e1d89 (patch)
tree67dd67d2c4c18e5c36654dfe569e3085bd262ba5 /drivers
parent8d42db189ca99703f0f4f91c477cb54808c8eaaa (diff)
downloadop-kernel-dev-04a2e6a5cbf84e85fe86de0a18f6509b147e1d89.zip
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[PATCH] pid: make session_of_pgrp use struct pid instead of pid_t
To properly implement a pid namespace I need to deal exclusively in terms of struct pid, because pid_t values become ambiguous. To this end session_of_pgrp is transformed to take and return a struct pid pointer. To avoid the need to worry about reference counting I now require my caller to hold the appropriate locks. Leaving callers repsonsible for increasing the reference count if they need access to the result outside of the locks. Since session_of_pgrp currently only has one caller and that caller simply uses only test the result for equality with another process group, the locking change means I don't actually have to acquire the tasklist_lock at all. tiocspgrp is also modified to take and release the lock. The logic there is a little more complicated but nothing I won't need when I convert pgrp of a tty to a struct pid pointer. 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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/char/tty_io.c24
1 files changed, 17 insertions, 7 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index abfe24d..95f3596 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -2990,7 +2990,8 @@ static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t
static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
{
- pid_t pgrp;
+ struct pid *pgrp;
+ pid_t pgrp_nr;
int retval = tty_check_change(real_tty);
if (retval == -EIO)
@@ -3001,14 +3002,23 @@ static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t
(current->signal->tty != real_tty) ||
(real_tty->session != process_session(current)))
return -ENOTTY;
- if (get_user(pgrp, p))
+ if (get_user(pgrp_nr, p))
return -EFAULT;
- if (pgrp < 0)
+ if (pgrp_nr < 0)
return -EINVAL;
- if (session_of_pgrp(pgrp) != process_session(current))
- return -EPERM;
- real_tty->pgrp = pgrp;
- return 0;
+ rcu_read_lock();
+ pgrp = find_pid(pgrp_nr);
+ retval = -ESRCH;
+ if (!pgrp)
+ goto out_unlock;
+ retval = -EPERM;
+ if (session_of_pgrp(pgrp) != task_session(current))
+ goto out_unlock;
+ retval = 0;
+ real_tty->pgrp = pgrp_nr;
+out_unlock:
+ rcu_read_unlock();
+ return retval;
}
/**
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