[vfs:work.acl 8/9] fs/nfs/nfs3acl.c:43:2: note: in expansion of macro 'cmpxchg'

[kbuild test robot <fengguang.wu@xxxxxxxxx>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git work.acl
head:   016a469fef396cd7e7143c8692043f25fc3a0ae2
commit: 9582ceaf8b5fc27a82803f2e6db5edca751928a2 [8/9] posix_acl: Inode acl caching fixes
config: m68k-allmodconfig (attached as .config)
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        git checkout 9582ceaf8b5fc27a82803f2e6db5edca751928a2
        # save the attached .config to linux build tree
        make.cross ARCH=m68k 

All warnings (new ones prefixed by >>):

   In file included from arch/m68k/include/asm/atomic.h:6:0,
                    from include/linux/atomic.h:4,
                    from include/linux/spinlock.h:406,
                    from include/linux/wait.h:8,
                    from include/linux/fs.h:5,
                    from fs/nfs/nfs3acl.c:1:
   fs/nfs/nfs3acl.c: In function 'nfs3_abort_get_acl':
   arch/m68k/include/asm/cmpxchg.h:121:3: warning: value computed is not used [-Wunused-value]
     ((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o),     \
      ^
>> fs/nfs/nfs3acl.c:43:2: note: in expansion of macro 'cmpxchg'
     cmpxchg(p, sentinel, ACL_NOT_CACHED);
     ^
--
   In file included from arch/m68k/include/asm/atomic.h:6:0,
                    from include/linux/atomic.h:4,
                    from include/linux/spinlock.h:406,
                    from include/linux/mmzone.h:7,
                    from include/linux/gfp.h:5,
                    from include/linux/slab.h:14,
                    from fs/posix_acl.c:14:
   fs/posix_acl.c: In function 'get_acl':
   arch/m68k/include/asm/cmpxchg.h:121:3: warning: value computed is not used [-Wunused-value]
     ((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o),     \
      ^
>> fs/posix_acl.c:147:3: note: in expansion of macro 'cmpxchg'
      cmpxchg(p, sentinel, ACL_NOT_CACHED);
      ^

vim +/cmpxchg +43 fs/nfs/nfs3acl.c

   > 1	#include <linux/fs.h>
     2	#include <linux/gfp.h>
     3	#include <linux/nfs.h>
     4	#include <linux/nfs3.h>
     5	#include <linux/nfs_fs.h>
     6	#include <linux/posix_acl_xattr.h>
     7	#include <linux/nfsacl.h>
     8	
     9	#include "internal.h"
    10	#include "nfs3_fs.h"
    11	
    12	#define NFSDBG_FACILITY	NFSDBG_PROC
    13	
    14	/*
    15	 * nfs3_prepare_get_acl, nfs3_complete_get_acl, nfs3_abort_get_acl: Helpers for
    16	 * caching get_acl results in a race-free way.  See fs/posix_acl.c:get_acl()
    17	 * for explanations.
    18	 */
    19	static void nfs3_prepare_get_acl(struct posix_acl **p)
    20	{
    21		struct posix_acl *sentinel = uncached_acl_sentinel(current);
    22	
    23		if (cmpxchg(p, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED) {
    24			/* Not the first reader or sentinel already in place. */
    25		}
    26	}
    27	
    28	static void nfs3_complete_get_acl(struct posix_acl **p, struct posix_acl *acl)
    29	{
    30		struct posix_acl *sentinel = uncached_acl_sentinel(current);
    31	
    32		/* Only cache the ACL if our sentinel is still in place. */
    33		posix_acl_dup(acl);
    34		if (cmpxchg(p, sentinel, acl) != sentinel)
    35			posix_acl_release(acl);
    36	}
    37	
    38	static void nfs3_abort_get_acl(struct posix_acl **p)
    39	{
    40		struct posix_acl *sentinel = uncached_acl_sentinel(current);
    41	
    42		/* Remove our sentinel upon failure. */
  > 43		cmpxchg(p, sentinel, ACL_NOT_CACHED);
    44	}
    45	
    46	struct posix_acl *nfs3_get_acl(struct inode *inode, int type)

---
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