On Wed, May 15, 2024 at 09:58:35AM +0200, Marco Elver wrote: > On Wed, 15 May 2024 at 01:47, Paul E. McKenney <paulmck@xxxxxxxxxx> wrote: > > On Mon, May 13, 2024 at 10:13:49AM +0200, Marco Elver wrote: > > +Use of volatile and __data_racy > > +------------------------------- > > + > > +Adding the volatile keyword to the declaration of a variable causes both > > +the compiler and KCSAN to treat all reads from that variable as if they > > +were protected by READ_ONCE() and all writes to that variable as if they > > +were protected by WRITE_ONCE(). > "volatile" isn't something we encourage, right? In which case, I think > to avoid confusion we should not mention volatile. After all we have > this: Documentation/process/volatile-considered-harmful.rst Since you mentioned this document, the other day I was reading volatile-considered-harmful.rst document, and I was surprised that there is no reference for READ_ONCE() primitive at all (same for WRITE_ONCE). # grep -c READ_ONCE Documentation/process/volatile-considered-harmful.rst 0 >From my perspective, READ_ONCE() is another way of doing real memory read (volatile) when you really need, at the same time keeping the compiler free to optimize and reuse the value that was read. Should volatile-considered-harmful.rst be also expanded to cover READ_ONCE()? Thanks! --breno
