Re: kmalloc without GFP_xxx?

[Manfred Spraul <manfred@colorfullife.com>]

Hi,

One question from Linux-Tag was about the lack of documentation about/in 
the kernel. I try to maintain docbook entries when I modify code, even 
though I think it's mostly wasted time: Virtually noone reads it anyway, 
instead armchair logic on lkml.

Steven wrote:

>Here we see that task 2 can spin with interrupts off, while the first task
>is servicing an interrupt, and God forbid if the IRQ handler sends some
>kind of SMP signal to the CPU running task 2 since that would be a
>deadlock.  Granted, this is a hypothetical situation, but makes using
>spin_lock with interrupts enabled a little scary.
>  
>
Not, it's not even a hypothetical situation. It's an explicitely 
forbidden situation: SMP signals are sent with smp_call_function and the 
documentation to that function clearly says:
 *
 * You must not call this function with disabled interrupts or from a
 * hardware interrupt handler or from a bottom half handler.
 */

--
    Manfred