Re: [PATCH 2/2 v3] cxl/region: Use cond_guard() in show_targetN()

From: Ira Weiny <ira.weiny@intel.com>
To: "Fabio M. De Francesco"
	<fabio.maria.de.francesco@linux.intel.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	Dan Williams <dan.j.williams@intel.com>
Cc: <linux-kernel@vger.kernel.org>, kernel test robot <lkp@intel.com>,
	<oe-kbuild-all@lists.linux.dev>, <linux-cxl@vger.kernel.org>,
	Dave Jiang <dave.jiang@intel.com>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	"Ingo Molnar" <mingo@kernel.org>, Ira Weiny <ira.weiny@intel.com>
Subject: Re: [PATCH 2/2 v3] cxl/region: Use cond_guard() in show_targetN()
Date: Wed, 7 Feb 2024 07:45:50 -0800	[thread overview]
Message-ID: <65c3a5aed6291_3aceba2947b@iweiny-mobl.notmuch> (raw)
In-Reply-To: <4546212.LvFx2qVVIh@fdefranc-mobl3>

Fabio M. De Francesco wrote:
> On Wednesday, 7 February 2024 02:54:34 CET kernel test robot wrote:
> > Hi Fabio,
> > 
> > kernel test robot noticed the following build warnings:
> > 
> > [auto build test WARNING on linus/master]
> > [also build test WARNING on v6.8-rc3 next-20240206]
> > [cannot apply to cxl/next cxl/pending]
> > [If your patch is applied to the wrong git tree, kindly drop us a note.
> > And when submitting patch, we suggest to use '--base' as documented in
> > https://git-scm.com/docs/git-format-patch#_base_tree_information]
> > 
> > url:   
> > https://github.com/intel-lab-lkp/linux/commits/Fabio-M-De-Francesco/cleanup
> > -Add-cond_guard-to-conditional-guards/20240206-203110 base:   linus/master
> > patch link:   
> > https://lore.kernel.org/r/20240206121301.7225-3-fabio.maria.de.francesco%40
> > linux.intel.com patch subject: [PATCH 2/2 v3] cxl/region: Use cond_guard()
> > in show_targetN() config: s390-allyesconfig
> > (https://download.01.org/0day-ci/archive/20240207/202402070919.0zuYCxMS-lkp
> > @intel.com/config) compiler: s390-linux-gcc (GCC) 13.2.0
> > reproduce (this is a W=1 build):
> > (https://download.01.org/0day-ci/archive/20240207/202402070919.0zuYCxMS-lkp
> > @intel.com/reproduce)
> > 
> > If you fix the issue in a separate patch/commit (i.e. not just a new version
> > of the same patch/commit), kindly add following tags
> > 
> > | Reported-by: kernel test robot <lkp@intel.com>
> > | Closes:
> > | https://lore.kernel.org/oe-kbuild-all/202402070919.0zuYCxMS-lkp@intel.com
> > | /
> > All warnings (new ones prefixed by >>):
> > 
> >    drivers/cxl/core/region.c: In function 'show_targetN':
> > >> drivers/cxl/core/region.c:670:70: warning: suggest braces around empty
> > >> body in an 'else' statement [-Wempty-body]
> >      670 |         cond_guard(rwsem_read_intr, return -EINTR,
> > &cxl_region_rwsem);
> >          |                                                                      
> ^
> 
> I think that this warning deserves attention and braces should be added around 
> the 'else' empty body. I'm going to send v4:
> 
> #define cond_guard(_name, _ret, args...) \
>         CLASS(_name, scope)(args); \
>         if (!__guard_ptr(_name)(&scope)) _ret; \
>         else { }
>

I think this is a good addition.  If the user forgets ';' at the end of
the cond_guard() we could have a hidden side effect similar to what Dan
was concerned about...  This guarantees that won't happen.

Score one for the bots!
Ira