Re: [PATCH] checkpatch: Make the memory barrier test noisier

2013-09-28 Thread Peter Zijlstra
On Sat, Sep 28, 2013 at 01:40:27AM +0200, Oliver Neukum wrote: > On Fri, 2013-09-27 at 16:50 +0200, Peter Zijlstra wrote: > > On Fri, Sep 27, 2013 at 07:34:55AM -0700, Joe Perches wrote: > > > That would make it seem as if all barriers are SMP no? > > > > I would think any memory barrier is orderi

Re: [PATCH] checkpatch: Make the memory barrier test noisier

2013-09-27 Thread Oliver Neukum
On Fri, 2013-09-27 at 16:50 +0200, Peter Zijlstra wrote: > On Fri, Sep 27, 2013 at 07:34:55AM -0700, Joe Perches wrote: > > That would make it seem as if all barriers are SMP no? > > I would think any memory barrier is ordering against someone else; if > not smp then a device/hardware -- like for

Re: [PATCH] checkpatch: Make the memory barrier test noisier

2013-09-27 Thread Paul E. McKenney
On Fri, Sep 27, 2013 at 05:34:34PM +0200, Peter Zijlstra wrote: > On Fri, Sep 27, 2013 at 08:17:50AM -0700, Paul E. McKenney wrote: > > > Barriers are fundamentally about order; and order only makes sense if > > > there's more than 1 party to the game. > > > > Oddly enough, there is one exception

Re: [PATCH] checkpatch: Make the memory barrier test noisier

2013-09-27 Thread Peter Zijlstra
On Fri, Sep 27, 2013 at 08:17:50AM -0700, Paul E. McKenney wrote: > > Barriers are fundamentally about order; and order only makes sense if > > there's more than 1 party to the game. > > Oddly enough, there is one exception that proves the rule... On Itanium, > suppose we have the following code,

Re: [PATCH] checkpatch: Make the memory barrier test noisier

2013-09-27 Thread Paul E. McKenney
On Fri, Sep 27, 2013 at 04:50:07PM +0200, Peter Zijlstra wrote: > On Fri, Sep 27, 2013 at 07:34:55AM -0700, Joe Perches wrote: > > That would make it seem as if all barriers are SMP no? > > I would think any memory barrier is ordering against someone else; if > not smp then a device/hardware -- li

Re: [PATCH] checkpatch: Make the memory barrier test noisier

2013-09-27 Thread Peter Zijlstra
On Fri, Sep 27, 2013 at 07:34:55AM -0700, Joe Perches wrote: > That would make it seem as if all barriers are SMP no? I would think any memory barrier is ordering against someone else; if not smp then a device/hardware -- like for instance the hardware page table walker. Barriers are fundamentall

Re: [PATCH] checkpatch: Make the memory barrier test noisier

2013-09-27 Thread Joe Perches
On Fri, 2013-09-27 at 16:26 +0200, Peter Zijlstra wrote: > On Fri, Sep 27, 2013 at 07:14:17AM -0700, Joe Perches wrote: > > Peter Zijlstra prefers that comments be required near uses > > of memory barriers. > > > > Change the message level for memory barrier uses from a > > --strict test only to a

Re: [PATCH] checkpatch: Make the memory barrier test noisier

2013-09-27 Thread Peter Zijlstra
On Fri, Sep 27, 2013 at 07:14:17AM -0700, Joe Perches wrote: > Peter Zijlstra prefers that comments be required near uses > of memory barriers. > > Change the message level for memory barrier uses from a > --strict test only to a normal WARN so it's always emitted. > > This might produce false po