Messages in this thread Patch in this message | | | Date | Sat, 6 Feb 2010 22:31:30 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: [2.6.33-rc5] tty: possible irq lock inversion dependency in tty_fasync |
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On Sun, 7 Feb 2010, Tetsuo Handa wrote: > > Below problem (which was introduced between 2.6.33-rc4 and 2.6.33-rc5) is > not yet fixed as of 2.6.33-rc7. > "git bisect start v2.6.33-rc5 v2.6.33-rc4" reported that > 703625118069f9f8960d356676662d3db5a9d116 tty: fix race in tty_fasync > is first bad commit.
Yeah. I think we need to just revert that commit.
Or maybe we could just do the following, rather than revert it outright: just get a ref to the 'struct pid' while holding the spinlock, and then releasing it after doing the __f_setown() call.
That way we know 'pid' isn't going away.
What? Untested, of course.
Linus
--- drivers/char/tty_io.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index c6f3b48..dcb9083 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -1951,8 +1951,10 @@ static int tty_fasync(int fd, struct file *filp, int on) pid = task_pid(current); type = PIDTYPE_PID; } - retval = __f_setown(filp, pid, type, 0); + get_pid(pid); spin_unlock_irqrestore(&tty->ctrl_lock, flags); + retval = __f_setown(filp, pid, type, 0); + put_pid(pid); if (retval) goto out; } else {
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