Re: [PATCH] unnecessary blocking interrupts in exit_notify()

From: Matthias Urlichs (smurf@noris.de)
Date: Sun Mar 19 2000 - 21:33:37 EST

Jun Sun:
> On Fri, 17 Mar 2000, Linus Torvalds wrote:
> > It can deadlock due to an interrupt doing a read_lock() on the
> > tasklist_lock while we hold the write lock.
> >
> On the other hand, why would an interrupt routine need to acquire
> the read lock on tasklist_lock at first place?

Hmmm. The task list is read-locked by a whole lot of procedures,
including do_SAK(). Or kill_fasync() by way of send_sigio().
A few other places come to mind, but kill_fasync() definitely is the
killer for your proposed patch.

I would say that forbidding to send signals from interrupt (or BH) context
is a Very Bad Thing. 

-- 
Matthias Urlichs  |  noris network GmbH   |   smurf@noris.de  |  ICQ: 20193661
The quote was selected randomly. Really.    |      http://www.noris.de/~smurf/
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