Hi Robert,
On Friday 26 April 2002 21:19, Robert Love wrote:
> On Fri, 2002-04-26 at 04:52, Emmanuel Michon wrote:
> > 2. What is the reality behind: ``things which sleep'', is it really a problem
> > to use copy_from_user/copy_to_user holding a spinlock?
>
> Yes, they sleep.
Well, I think he really wanted to know why it's bad. Emmanuel, suppose process A
takes spinlock S then sleeps. Process B is then scheduled and tries to acquire
S - bang, deadlock: Process A can't release the spinlock because it's sleeping.
Let alone the fact that another CPU trying to acquire S is going to end up
stalled potentially many milliseconds before process A wakes up again and
releases the spinlock.
-- Daniel - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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