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Date: Wed, 15 Nov 2023 14:06:24 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>, Dave Jiang <dave.jiang@intel.com>,
	linux-cxl@vger.kernel.org, Jonathan.Cameron@huawei.com,
	dave@stgolabs.net, alison.schofield@intel.com,
	vishal.l.verma@intel.com
Subject: Re: [PATCH] cxl: Add cxl_region_rwsem around commit_end write during
 decoder enumeration
Message-ID: <20231115130624.GK4779@noisy.programming.kicks-ass.net>
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In-Reply-To: <20231115130113.GG3818@noisy.programming.kicks-ass.net>

On Wed, Nov 15, 2023 at 02:01:14PM +0100, Peter Zijlstra wrote:
> On Fri, Nov 10, 2023 at 12:21:56PM -0800, Dan Williams wrote:
> 
> >         /* decoders are enabled if committed */
> > -       if (committed) {
> > +       if (committed) scoped_guard(rwsem_write, &cxl_region_rwsem) {
> >                 cxld->flags |= CXL_DECODER_F_ENABLE;
> >                 if (ctrl & CXL_HDM_DECODER0_CTRL_LOCK)
> >                         cxld->flags |= CXL_DECODER_F_LOCK;
> > 
> > 
> > The alternative is a much more violent re-ident of the code to turn:
> > 
> >     if (...) scoped_guard(...) {
> > 	...
> >     } else {
> >         ...
> >     }
> > 
> > ...into:
> > 
> >     if (...) {
> >         scoped_guard(...) {
> > 	    ...
> >         }
> >     } else {
> >         ...
> >     }
> > 
> 
> What's wrong with:
> 
> 	if (...) {
> 		guard(rwsem_write, &cxl_region_rwsem);

Uh, that is:
		guard(rwsem_write)(&ctl_region_rwsem);

> 		...
> 	} else {
> 		...
> 	}
> 
> ?