Re: SIGKILL

[Darshan Ghumare <darshan.ghumare@xxxxxxxxx>]

On Fri, Jan 20, 2012 at 12:32 PM, Dave Hylands <dhylands@xxxxxxxxx> wrote:

Hi Darshan,

HI Dave,
 

Replying to all this time....

Thanks.

On Thu, Jan 19, 2012 at 9:41 PM, Darshan Ghumare
<darshan.ghumare@xxxxxxxxx> wrote:

...snip...

> What if,
> spin_lock_irqsave(&lock, flags);
> for ( ; ; )
> {
>        ;
> }
> spin_lock_irqrestore(&lock, flags);

Since you're using spinlocks and disabling interrupts, this would be
running in kernel space.

On a single core machine - you'll have locked up your entire computer.

On a multi-core machine you'll have locked up one core.

You don't need to use the spinlock, just disabling interrupts is
sufficient. Even on a multicore machine, the spinlocks would just
prevent a second core from executing the code if it tried to acquire
the same spinlock.

I don't think that there is any convenient way to kill such a thread.

IMHO, signals are handled when process is about to switch back to user-mode.
If that is the case then what if, there are two threads(in user-mode) in the process where one is stuck
in the syscall which has infinite loop & other is executing some task in the user-mode, then still this process can not be killed?

--
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com

Regards
Darshan


-- 
Darshan®
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