Re: [PATCH v1] NFSD: Don't start nfsd threads from a pool_threads write

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

Hi Chuck,

kernel test robot noticed the following build errors:

[auto build test ERROR on brauner-vfs/vfs.all]
[also build test ERROR on linus/master v7.3-rc6 next-20261008]
[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/Chuck-Lever/NFSD-Don-t-start-nfsd-threads-from-a-pool_threads-write/20261009-104017
base:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git vfs.all
patch link:    https://lore.kernel.org/r/20261009144017.1284586-1-cel%40kernel.org
patch subject: [PATCH v1] NFSD: Don't start nfsd threads from a pool_threads write
config: parisc64-defconfig (https://download.01.org/0day-ci/archive/20261010/202610101235.HaenlCPb-lkp@intel.com/config)
compiler: hppa64-linux-gcc (GCC) 16.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20261010/202610101235.HaenlCPb-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/202610101235.HaenlCPb-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from include/linux/log2.h:12,
                    from include/asm-generic/div64.h:55,
                    from ./arch/parisc/include/generated/asm/div64.h:1,
                    from include/linux/math.h:6,
                    from include/linux/math64.h:6,
                    from include/linux/time64.h:5,
                    from include/linux/restart_block.h:9,
                    from include/linux/thread_info.h:14,
                    from include/asm-generic/preempt.h:5,
                    from ./arch/parisc/include/generated/asm/preempt.h:1,
                    from include/linux/preempt.h:107,
                    from include/linux/spinlock.h:56,
                    from include/linux/mmzone.h:8,
                    from include/linux/gfp.h:7,
                    from include/linux/slab.h:17,
                    from fs/nfsd/nfsctl.c:8:
   fs/nfsd/nfsctl.c: In function 'write_pool_threads':
>> fs/nfsd/nfsctl.c:504:48: error: 'nn' undeclared (first use in this function)
     504 |         if (size > 0 && test_bit(NFSD_NET_UP, &nn->flags)) {
         |                                                ^~
   include/linux/bitops.h:44:44: note: in definition of macro 'bitop'
      44 |           __builtin_constant_p((uintptr_t)(addr) != (uintptr_t)NULL) && \
         |                                            ^~~~
   fs/nfsd/nfsctl.c:504:25: note: in expansion of macro 'test_bit'
     504 |         if (size > 0 && test_bit(NFSD_NET_UP, &nn->flags)) {
         |                         ^~~~~~~~
   fs/nfsd/nfsctl.c:504:48: note: each undeclared identifier is reported only once for each function it appears in
   include/linux/bitops.h:44:44: note: in definition of macro 'bitop'
      44 |           __builtin_constant_p((uintptr_t)(addr) != (uintptr_t)NULL) && \
         |                                            ^~~~
   fs/nfsd/nfsctl.c:504:25: note: in expansion of macro 'test_bit'
     504 |         if (size > 0 && test_bit(NFSD_NET_UP, &nn->flags)) {
         |                         ^~~~~~~~


vim +/nn +504 fs/nfsd/nfsctl.c

   449	
   450	/*
   451	 * write_pool_threads - Set or report the configured number of threads per pool
   452	 *
   453	 * Input:
   454	 *			buf:		ignored
   455	 *			size:		zero
   456	 *
   457	 * OR
   458	 *
   459	 * Input:
   460	 *			buf:		C string containing whitespace-
   461	 *					separated unsigned integer values
   462	 *					representing the number of NFSD
   463	 *					threads to start in each pool
   464	 *			size:		non-zero length of C string in @buf
   465	 * Output:
   466	 *	On success:	passed-in buffer filled with '\n'-terminated C
   467	 *			string containing integer values representing the
   468	 *			configured number of NFSD threads in each pool;
   469	 *			return code is the size in bytes of the string
   470	 *	On error:	return code is zero or a negative errno value
   471	 */
   472	static ssize_t write_pool_threads(struct file *file, char *buf, size_t size)
   473	{
   474		/* if size > 0, look for an array of number of threads per node
   475		 * and apply them  then write out number of threads per node as reply
   476		 */
   477		char *mesg = buf;
   478		int i;
   479		int rv;
   480		int len;
   481		int npools;
   482		int *nthreads;
   483		struct net *net = netns(file);
   484	
   485		mutex_lock(&nfsd_mutex);
   486		npools = nfsd_nrpools(net);
   487		if (npools == 0) {
   488			/*
   489			 * NFS is shut down.  The admin can start it by
   490			 * writing to the threads file but NOT the pool_threads
   491			 * file, sorry.  Report zero threads.
   492			 */
   493			mutex_unlock(&nfsd_mutex);
   494			strcpy(buf, "0\n");
   495			return strlen(buf);
   496		}
   497	
   498		nthreads = kzalloc_objs(int, npools);
   499		rv = -ENOMEM;
   500		if (nthreads == NULL)
   501			goto out_free;
   502	
   503		/* Threads started now would run without NFSv4 state. */
 > 504		if (size > 0 && test_bit(NFSD_NET_UP, &nn->flags)) {
   505			for (i = 0; i < npools; i++) {
   506				rv = get_int(&mesg, &nthreads[i]);
   507				if (rv == -ENOENT)
   508					break;		/* fewer numbers than pools */
   509				if (rv)
   510					goto out_free;	/* syntax error */
   511				rv = -EINVAL;
   512				if (nthreads[i] < 0)
   513					goto out_free;
   514				trace_nfsd_ctl_pool_threads(net, i, nthreads[i]);
   515			}
   516	
   517			/*
   518			 * There must always be a thread in pool 0; the admin
   519			 * can't shut down NFS completely using pool_threads.
   520			 */
   521			if (nthreads[0] == 0)
   522				nthreads[0] = 1;
   523	
   524			rv = nfsd_set_nrthreads(i, nthreads, net);
   525			if (rv)
   526				goto out_free;
   527		}
   528	
   529		rv = nfsd_get_nrthreads(npools, nthreads, net);
   530		if (rv)
   531			goto out_free;
   532	
   533		mesg = buf;
   534		size = SIMPLE_TRANSACTION_LIMIT;
   535		for (i = 0; i < npools && size > 0; i++) {
   536			snprintf(mesg, size, "%d%c", nthreads[i], (i == npools-1 ? '\n' : ' '));
   537			len = strlen(mesg);
   538			size -= len;
   539			mesg += len;
   540		}
   541		rv = mesg - buf;
   542	out_free:
   543		kfree(nthreads);
   544		mutex_unlock(&nfsd_mutex);
   545		return rv;
   546	}
   547	

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