Messages in this thread Patch in this message | | | Date | Thu, 14 May 2015 13:57:51 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH tip/core/rcu 2/3] documentation: Update rcu_dereference.txt based on WG21 discussions |
| |
On Wed, May 13, 2015 at 06:33:10PM +0000, Mathieu Desnoyers wrote: > ----- Original Message ----- > > From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> > > > > This commit provides another caveat for the care and feeding of pointers > > returned by rcu_dereference() that was pointed out in discussions within > > the C++ standards committee. > > > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Thank you, applied.
> BTW, reading through rcu_dereference.txt, I found a nit: > > operatiors -> operators
Hmmm... Almost like I was trying (and spectacularly failing) to write the document in French. ;-)
> Very interesting reading :)
Glad you liked it!
Thanx, Paul
> Thanks! > > Mathieu > > > --- > > Documentation/RCU/rcu_dereference.txt | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/Documentation/RCU/rcu_dereference.txt > > b/Documentation/RCU/rcu_dereference.txt > > index ceb05da5a5ac..2d05c9241a33 100644 > > --- a/Documentation/RCU/rcu_dereference.txt > > +++ b/Documentation/RCU/rcu_dereference.txt > > @@ -193,6 +193,11 @@ o Be very careful about comparing pointers obtained from > > pointer. Note that the volatile cast in rcu_dereference() > > will normally prevent the compiler from knowing too much. > > > > + However, please note that if the compiler knows that the > > + pointer takes on only one of two values, a not-equal > > + comparison will provide exactly the information that the > > + compiler needs to deduce the value of the pointer. > > + > > o Disable any value-speculation optimizations that your compiler > > might provide, especially if you are making use of feedback-based > > optimizations that take data collected from prior runs. Such > > -- > > 1.8.1.5 > > > > > > -- > Mathieu Desnoyers > EfficiOS Inc. > http://www.efficios.com >
| |