Re: __sync_lock_test_and_set on ARM

[David Daney <ddaney at avtrex dot com>]

Andrew Haley wrote:
> Phil Endecott writes:
>  > Andrew Haley wrote:
>  > > this stuff really should be done by the compiler. 
>  > 
>  > Yes.  I've filed a bug asking for a __sync_lock_test_and_set builtin:
>  > 
>  > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33413
>
> Surer, but the problem is that for most of the things we want to do
> (lightweight locks, for example) __sync_lock_test_and_set() doesn't
> really do what we need: we need compare_and_swap().  That's why the
> kernel helper is so useful, because it's robust even if we are on
> pre-ARMv6 hardware.

Probably the enhancement request should be expanded to include *all* the 
__sync_* atomic memory primitives  which includes compare_and_swap.


David Daney