lkml.org 
[lkml]   [2014]   [Apr]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Subjectquestion on read_barrier_depends
From
Date
Hi,

I am looking at memory ordering and a question hit me.
I was looking at the kfifo code. kfifo_put() has a barrier:

)[__kfifo->in & __tmp->kfifo.mask] = \
(typeof(*__tmp->type))__val; \
smp_wmb(); \
__kfifo->in++; \

Looking at kfifo_get()

__ret = !kfifo_is_empty(__tmp); \
if (__ret) { \
*(typeof(__tmp->type))__val = \
(__is_kfifo_ptr(__tmp) ? \

A thought struck me. There is no corresponding barrier. I cannot
help myself, but I think there needs to be a smp_read_barrier_depends()
between reading kfifo->in (in kfifo_is empty) and reading val.
What do you think?

Regards
Oliver




\
 
 \ /
  Last update: 2014-04-16 11:01    [W:0.067 / U:0.104 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site