linux-kernel - Re: [PATCH 1/2] drivers: md: dm-log.c: Remove unused variable 'sz'

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Message-ID: <20191202173909.GA15687@redhat.com>
Date:   Mon, 2 Dec 2019 12:39:10 -0500
From:   Mike Snitzer <snitzer@...hat.com>
To:     Jieun Kim <jieun.kim4758@...il.com>
Cc:     Alasdair Kergon <agk@...hat.com>, dm-devel@...hat.com,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 1/2] drivers: md: dm-log.c: Remove unused variable 'sz'

As you can see below: your patches to remove the seemingly unused sz
variables won't even compile.  The sz variable is used by the DMEMIT()
macro.

Nacked-by: Mike Snitzer <snitzer@...hat.com>

On Sun, Dec 01 2019 at  2:46am -0500,
kbuild test robot <lkp@...el.com> wrote:

> Hi Jieun,
> 
> Thank you for the patch! Yet something to improve:
> 
> [auto build test ERROR on dm/for-next]
> [also build test ERROR on v5.4 next-20191129]
> [if your patch is applied to the wrong git tree, please drop us a note to help
> improve the system. BTW, we also suggest to use '--base' option to specify the
> base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
> 
> url:    https://github.com/0day-ci/linux/commits/Jieun-Kim/drivers-md-dm-log-c-Remove-unused-variable-sz/20191201-134548
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git for-next
> config: i386-defconfig (attached as .config)
> compiler: gcc-7 (Debian 7.5.0-1) 7.5.0
> reproduce:
>         # save the attached .config to linux build tree
>         make ARCH=i386 
> 
> If you fix the issue, kindly add following tag
> Reported-by: kbuild test robot <lkp@...el.com>
> 
> All error/warnings (new ones prefixed by >>):
> 
>    In file included from include/linux/dm-dirty-log.h:16:0,
>                     from drivers/md/dm-log.c:13:
>    drivers/md/dm-log.c: In function 'core_status':
> >> include/linux/device-mapper.h:551:22: error: 'sz' undeclared (first use in this function); did you mean 's8'?
>     #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
>                          ^
> >> drivers/md/dm-log.c:788:3: note: in expansion of macro 'DMEMIT'
>       DMEMIT("1 %s", log->type->name);
>       ^~~~~~
>    include/linux/device-mapper.h:551:22: note: each undeclared identifier is reported only once for each function it appears in
>     #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
>                          ^
> >> drivers/md/dm-log.c:788:3: note: in expansion of macro 'DMEMIT'
>       DMEMIT("1 %s", log->type->name);
>       ^~~~~~
> --
>    In file included from include/linux/dm-dirty-log.h:16:0,
>                     from drivers//md/dm-log.c:13:
>    drivers//md/dm-log.c: In function 'core_status':
> >> include/linux/device-mapper.h:551:22: error: 'sz' undeclared (first use in this function); did you mean 's8'?
>     #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
>                          ^
>    drivers//md/dm-log.c:788:3: note: in expansion of macro 'DMEMIT'
>       DMEMIT("1 %s", log->type->name);
>       ^~~~~~
>    include/linux/device-mapper.h:551:22: note: each undeclared identifier is reported only once for each function it appears in
>     #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
>                          ^
>    drivers//md/dm-log.c:788:3: note: in expansion of macro 'DMEMIT'
>       DMEMIT("1 %s", log->type->name);
>       ^~~~~~
> 
> vim +/DMEMIT +788 drivers/md/dm-log.c
> 
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  776  
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  777  #define	DMEMIT_SYNC \
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  778  	if (lc->sync != DEFAULTSYNC) \
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  779  		DMEMIT("%ssync ", lc->sync == NOSYNC ? "no" : "")
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  780  
> 416cd17b198221 Heinz Mauelshagen  2008-04-24  781  static int core_status(struct dm_dirty_log *log, status_type_t status,
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  782  		       char *result, unsigned int maxlen)
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  783  {
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  784  	struct log_c *lc = log->context;
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  785  
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  786  	switch(status) {
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  787  	case STATUSTYPE_INFO:
> 315dcc226f066c Jonathan E Brassow 2007-05-09 @788  		DMEMIT("1 %s", log->type->name);
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  789  		break;
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  790  
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  791  	case STATUSTYPE_TABLE:
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  792  		DMEMIT("%s %u %u ", log->type->name,
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  793  		       lc->sync == DEFAULTSYNC ? 1 : 2, lc->region_size);
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  794  		DMEMIT_SYNC;
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  795  	}
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  796  
> 2a79ee10b97355 Jieun Kim          2019-12-01  797  	return 0;
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  798  }
> ^1da177e4c3f41 Linus Torvalds     2005-04-16  799  
> 
> :::::: The code at line 788 was first introduced by commit
> :::::: 315dcc226f066c1d3cef79283dcde807fe0e32d1 dm log: report fault status
> 
> :::::: TO: Jonathan E Brassow <jbrassow@...hat.com>
> :::::: CC: Linus Torvalds <torvalds@...dy.linux-foundation.org>
> 
> ---
> 0-DAY kernel test infrastructure                 Open Source Technology Center
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org Intel Corporation