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Date: Wed, 15 Nov 2023 14:01:13 +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: <20231115130113.GG3818@noisy.programming.kicks-ass.net>
References: <169948110840.509375.13862681045079385425.stgit@djiang5-mobl3>
 <654d5f7285171_af98d2949e@iweiny-mobl.notmuch>
 <654e90e4349f9_46f0294da@dwillia2-mobl3.amr.corp.intel.com.notmuch>
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In-Reply-To: <654e90e4349f9_46f0294da@dwillia2-mobl3.amr.corp.intel.com.notmuch>

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);
		...
	} else {
		...
	}

?