Messages in this thread | | | Date | Tue, 26 Jan 2010 14:11:28 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: [06/11] tty: fix race in tty_fasync |
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On Tue, 26 Jan 2010, Eric W. Biederman wrote:
> Greg KH <gregkh@suse.de> writes: > > > 2.6.27-stable review patch. If anyone has any objections, please let us know. > > Only that __f_setown by way of f_modown unconditionally enables interrupts. So > without touching f_modown as well in mainline we have nasty sounding lockdep warnings.
Hmm. That seems to be true in mainline too, isn't it?
So now we have: - tty_fasync() gets tty->ctrl_lock, with spin_lock_irqsave()
- it then calls __f_setown()
- which calls f_modown(),
- which does
write_lock_irq(&filp->f_owner.lock); .. write_unlock_irq(&filp->f_owner.lock);
which in turn enables interrupts while we still hold ctrl_lock.
so that whole commit 70362511806 was/is buggy in mainline too.
The minimal fix is likely to just make f_modown() use write_lock_irqsave/restore. Greg?
Linus
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