On Thu, Sep 21, 2017 at 04:29:01PM -0300, Guilherme G. Piccoli wrote: > In this specific portion of the write memory barriers description, > the documentation mentions sequential order of stores, which is > confusing since sequential ordering is not guaranteed. > > This patch tries to improve the doc in order to avoid any > mis-understanding. > > Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxxxxxxxxxx> Good catch, and you are quite correct, a write barrier orders only before and after itself, doing nothing to impose order on preceding writes among themselves. Applied, thank you! Thanx, Paul > --- > > v2: added Paul in CC. > > Documentation/memory-barriers.txt | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt > index b759a60624fd..a4bbbd1b63a0 100644 > --- a/Documentation/memory-barriers.txt > +++ b/Documentation/memory-barriers.txt > @@ -383,8 +383,8 @@ Memory barriers come in four basic varieties: > to have any effect on loads. > > A CPU can be viewed as committing a sequence of store operations to the > - memory system as time progresses. All stores before a write barrier will > - occur in the sequence _before_ all the stores after the write barrier. > + memory system as time progresses. All stores _before_ a write barrier > + will occur _before_ all the stores after the write barrier. > > [!] Note that write barriers should normally be paired with read or data > dependency barriers; see the "SMP barrier pairing" subsection. > -- > 2.14.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
