Re: [PATCH v4 2/2] kernfs: Replace per-fs global rwsem with per-fs hashed rwsem.
From: kernel test robot
Date: Wed Feb 02 2022 - 13:26:21 EST
Hi Imran,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on a70bf4a85b43cb952bd39dd948b103b1b3eb2cf8]
url: https://github.com/0day-ci/linux/commits/Imran-Khan/kernfs-use-hashed-mutex-and-spinlock-in-place-of-global-ones/20220202-225301
base: a70bf4a85b43cb952bd39dd948b103b1b3eb2cf8
config: um-i386_defconfig (https://download.01.org/0day-ci/archive/20220203/202202030237.zeUR5agU-lkp@xxxxxxxxx/config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
# https://github.com/0day-ci/linux/commit/e1946294e8a0e6eb1f9876e7521c92f92c8c4af9
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Imran-Khan/kernfs-use-hashed-mutex-and-spinlock-in-place-of-global-ones/20220202-225301
git checkout e1946294e8a0e6eb1f9876e7521c92f92c8c4af9
# save the config file to linux build tree
mkdir build_dir
make W=1 O=build_dir ARCH=um SUBARCH=i386 SHELL=/bin/bash fs/kernfs/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>
All warnings (new ones prefixed by >>):
fs/kernfs/dir.c: In function 'kernfs_dop_revalidate':
>> fs/kernfs/dir.c:1056:22: warning: variable 'root' set but not used [-Wunused-but-set-variable]
1056 | struct kernfs_root *root;
| ^~~~
fs/kernfs/dir.c: In function 'kernfs_iop_lookup':
fs/kernfs/dir.c:1126:22: warning: variable 'root' set but not used [-Wunused-but-set-variable]
1126 | struct kernfs_root *root;
| ^~~~
fs/kernfs/dir.c: In function 'kernfs_remove_by_name_ns':
fs/kernfs/dir.c:1572:11: warning: unused variable 'p_idx' [-Wunused-variable]
1572 | int idx, p_idx;
| ^~~~~
fs/kernfs/dir.c:1572:6: warning: unused variable 'idx' [-Wunused-variable]
1572 | int idx, p_idx;
| ^~~
fs/kernfs/dir.c:1571:22: warning: variable 'root' set but not used [-Wunused-but-set-variable]
1571 | struct kernfs_root *root;
| ^~~~
fs/kernfs/dir.c: In function 'kernfs_rename_ns':
fs/kernfs/dir.c:1607:22: warning: variable 'root' set but not used [-Wunused-but-set-variable]
1607 | struct kernfs_root *root;
| ^~~~
fs/kernfs/dir.c: In function 'kernfs_fop_readdir':
fs/kernfs/dir.c:1837:22: warning: variable 'root' set but not used [-Wunused-but-set-variable]
1837 | struct kernfs_root *root;
| ^~~~
vim +/root +1056 fs/kernfs/dir.c
ea015218f2f7ac Eric W. Biederman 2015-05-13 1052
d826e0365199cc Ian Kent 2021-06-15 1053 static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
d826e0365199cc Ian Kent 2021-06-15 1054 {
d826e0365199cc Ian Kent 2021-06-15 1055 struct kernfs_node *kn;
393c3714081a53 Minchan Kim 2021-11-18 @1056 struct kernfs_root *root;
d826e0365199cc Ian Kent 2021-06-15 1057
d826e0365199cc Ian Kent 2021-06-15 1058 if (flags & LOOKUP_RCU)
d826e0365199cc Ian Kent 2021-06-15 1059 return -ECHILD;
d826e0365199cc Ian Kent 2021-06-15 1060
c7e7c04274b13f Ian Kent 2021-07-16 1061 /* Negative hashed dentry? */
c7e7c04274b13f Ian Kent 2021-07-16 1062 if (d_really_is_negative(dentry)) {
c7e7c04274b13f Ian Kent 2021-07-16 1063 struct kernfs_node *parent;
c7e7c04274b13f Ian Kent 2021-07-16 1064
c7e7c04274b13f Ian Kent 2021-07-16 1065 /* If the kernfs parent node has changed discard and
c7e7c04274b13f Ian Kent 2021-07-16 1066 * proceed to ->lookup.
c7e7c04274b13f Ian Kent 2021-07-16 1067 */
c7e7c04274b13f Ian Kent 2021-07-16 1068 spin_lock(&dentry->d_lock);
c7e7c04274b13f Ian Kent 2021-07-16 1069 parent = kernfs_dentry_node(dentry->d_parent);
c7e7c04274b13f Ian Kent 2021-07-16 1070 if (parent) {
c7e7c04274b13f Ian Kent 2021-07-16 1071 spin_unlock(&dentry->d_lock);
393c3714081a53 Minchan Kim 2021-11-18 1072 root = kernfs_root(parent);
e1946294e8a0e6 Imran Khan 2022-02-03 1073 down_read_kernfs_rwsem(parent, LOCK_SELF, 0);
393c3714081a53 Minchan Kim 2021-11-18 1074 if (kernfs_dir_changed(parent, dentry)) {
e1946294e8a0e6 Imran Khan 2022-02-03 1075 up_read_kernfs_rwsem(parent);
c7e7c04274b13f Ian Kent 2021-07-16 1076 return 0;
c7e7c04274b13f Ian Kent 2021-07-16 1077 }
e1946294e8a0e6 Imran Khan 2022-02-03 1078 up_read_kernfs_rwsem(parent);
393c3714081a53 Minchan Kim 2021-11-18 1079 } else
c7e7c04274b13f Ian Kent 2021-07-16 1080 spin_unlock(&dentry->d_lock);
c7e7c04274b13f Ian Kent 2021-07-16 1081
c7e7c04274b13f Ian Kent 2021-07-16 1082 /* The kernfs parent node hasn't changed, leave the
c7e7c04274b13f Ian Kent 2021-07-16 1083 * dentry negative and return success.
c7e7c04274b13f Ian Kent 2021-07-16 1084 */
c7e7c04274b13f Ian Kent 2021-07-16 1085 return 1;
c7e7c04274b13f Ian Kent 2021-07-16 1086 }
d826e0365199cc Ian Kent 2021-06-15 1087
d826e0365199cc Ian Kent 2021-06-15 1088 kn = kernfs_dentry_node(dentry);
393c3714081a53 Minchan Kim 2021-11-18 1089 root = kernfs_root(kn);
e1946294e8a0e6 Imran Khan 2022-02-03 1090 down_read_kernfs_rwsem(kn, LOCK_SELF, 0);
d826e0365199cc Ian Kent 2021-06-15 1091
d826e0365199cc Ian Kent 2021-06-15 1092 /* The kernfs node has been deactivated */
d826e0365199cc Ian Kent 2021-06-15 1093 if (!kernfs_active(kn))
d826e0365199cc Ian Kent 2021-06-15 1094 goto out_bad;
d826e0365199cc Ian Kent 2021-06-15 1095
d826e0365199cc Ian Kent 2021-06-15 1096 /* The kernfs node has been moved? */
d826e0365199cc Ian Kent 2021-06-15 1097 if (kernfs_dentry_node(dentry->d_parent) != kn->parent)
d826e0365199cc Ian Kent 2021-06-15 1098 goto out_bad;
d826e0365199cc Ian Kent 2021-06-15 1099
d826e0365199cc Ian Kent 2021-06-15 1100 /* The kernfs node has been renamed */
d826e0365199cc Ian Kent 2021-06-15 1101 if (strcmp(dentry->d_name.name, kn->name) != 0)
d826e0365199cc Ian Kent 2021-06-15 1102 goto out_bad;
d826e0365199cc Ian Kent 2021-06-15 1103
d826e0365199cc Ian Kent 2021-06-15 1104 /* The kernfs node has been moved to a different namespace */
d826e0365199cc Ian Kent 2021-06-15 1105 if (kn->parent && kernfs_ns_enabled(kn->parent) &&
d826e0365199cc Ian Kent 2021-06-15 1106 kernfs_info(dentry->d_sb)->ns != kn->ns)
d826e0365199cc Ian Kent 2021-06-15 1107 goto out_bad;
d826e0365199cc Ian Kent 2021-06-15 1108
e1946294e8a0e6 Imran Khan 2022-02-03 1109 up_read_kernfs_rwsem(kn);
d826e0365199cc Ian Kent 2021-06-15 1110 return 1;
d826e0365199cc Ian Kent 2021-06-15 1111 out_bad:
e1946294e8a0e6 Imran Khan 2022-02-03 1112 up_read_kernfs_rwsem(kn);
d826e0365199cc Ian Kent 2021-06-15 1113 return 0;
d826e0365199cc Ian Kent 2021-06-15 1114 }
d826e0365199cc Ian Kent 2021-06-15 1115
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0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx