Re: [PATCH] Documentation/preempt-locking.txt clarification

[Andrew Morton <akpm@osdl.org>]

Thomas Hood <jdthood@yahoo.co.uk> wrote:
>
> On Wed, 2004-11-10 at 09:57, Andrew Morton wrote:
>  > I guess it's saying ...
> 
>  Thanks for the explanation.  I include a new patch which incorporates
>  your example.  I am in no position to judge the _truth_ of the
>  statements in this document; I am only hoping to _understand_ them.  :)

I think the statement is in fact false.  Ingo, what's your take on this
paragraph, from preempt-locking.txt?


  An additional concern is proper usage of local_irq_disable and
  local_irq_save.  These may be used to protect from preemption, however,
  on exit, if preemption may be enabled, a test to see if preemption is
  required should be done.  If these are called from the spin_lock and
  read/write lock macros, the right thing is done.  They may also be called
  within a spin-lock protected region, however, if they are ever called
  outside of this context, a test for preemption should be made.  Do note
  that calls from interrupt context or bottom half/ tasklets are also
  protected by preemption locks and so may use the versions which do not
  check preemption.