lkml.org 
[lkml]   [2006]   [Mar]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRE: Fix unlock_buffer() to work the same way as bit_unlock()
Date
Nick Piggin wrote on Tuesday, March 28, 2006 12:11 AM
> OK, that's fair enough and I guess you do need a barrier there.
> However, should the mb__after barrier still remain? The comment
> in wake_up_bit suggests yes, and there is similar code in
> unlock_page.

Question on unlock_page:

void fastcall unlock_page(struct page *page)
{
smp_mb__before_clear_bit();
if (!TestClearPageLocked(page))
BUG();
smp_mb__after_clear_bit();
wake_up_page(page, PG_locked);
}

Assuming test_and_clear_bit() on all arch does what the API is
called for with full memory fence around the atomic op, why do
you need smp_mb__before_clear_bit and smp_mb__after_clear_bit?
Aren't they redundant?

- Ken
-
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/

\
 
 \ /
  Last update: 2006-03-29 08:52    [W:0.130 / U:0.200 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site