Re: [PATCH nfsd-next] SQUASH sunrpc: allow svc threads to fail initialisation cleanly

[kernel test robot <lkp@intel.com>]

Hi NeilBrown,

kernel test robot noticed the following build errors:

[auto build test ERROR on next-20240913]
[cannot apply to trondmy-nfs/linux-next v6.11 v6.11-rc7 v6.11-rc6 linus/master v6.11]
[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/NeilBrown/SQUASH-sunrpc-allow-svc-threads-to-fail-initialisation-cleanly/20240916-074739
base:   next-20240913
patch link:    https://lore.kernel.org/r/172644394073.17050.16376953609629336068%40noble.neil.brown.name
patch subject: [PATCH nfsd-next] SQUASH sunrpc: allow svc threads to fail initialisation cleanly
config: x86_64-rhel-8.3-rust (https://download.01.org/0day-ci/archive/20240916/202409161022.FCpNdJMX-lkp@intel.com/config)
compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240916/202409161022.FCpNdJMX-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/202409161022.FCpNdJMX-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from fs/nfsd/trace.c:4:
   In file included from fs/nfsd/trace.h:18:
   In file included from fs/nfsd/nfsfh.h:12:
>> include/linux/sunrpc/svc.h:333:2: error: call to undeclared function 'smb_mb'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     333 |         smb_mb();
         |         ^
   1 error generated.
--
   In file included from fs/nfsd/export.c:19:
   In file included from include/linux/sunrpc/svc_xprt.h:11:
>> include/linux/sunrpc/svc.h:333:2: error: call to undeclared function 'smb_mb'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     333 |         smb_mb();
         |         ^
   fs/nfsd/export.c:1020:17: warning: variable 'inode' set but not used [-Wunused-but-set-variable]
    1020 |         struct inode            *inode;
         |                                  ^
   1 warning and 1 error generated.


vim +/smb_mb +333 include/linux/sunrpc/svc.h

   313	
   314	/**
   315	 * svc_thread_init_status - report whether thread has initialised successfully
   316	 * @rqstp: the thread in question
   317	 * @err: errno code
   318	 *
   319	 * After performing any initialisation that could fail, and before starting
   320	 * normal work, each sunrpc svc_thread must call svc_thread_init_status()
   321	 * with an appropriate error, or zero.
   322	 *
   323	 * If zero is passed, the thread is ready and must continue until
   324	 * svc_thread_should_stop() returns true.  If a non-zero error is passed
   325	 * the call will not return - the thread will exit.
   326	 */
   327	static inline void svc_thread_init_status(struct svc_rqst *rqstp, int err)
   328	{
   329		rqstp->rq_err = err;
   330		/* memory barrier ensures assignment to error above is visible before
   331		 * waitqueue_active() test below completes.
   332		 */
 > 333		smb_mb();
   334		wake_up_var(&rqstp->rq_err);
   335		if (err)
   336			kthread_exit(1);
   337	}
   338	

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