Re: [PATCH bpf-next v2 4/8] bpf: Introduce cgroup iter

kernel test robot
2022-06-11T06:23:39Z

Hi Yosry,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on bpf-next/master]

url: https://github.com/intel-lab-lkp/linux/commits/Yosry-Ahmed/bpf-rstat-cgroup-hierarchical-stats/20220611-034720
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: m68k-defconfig (https://download.01.org/0day-ci/archive/20220611/202206111453.xWWh2wMK-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 11.3.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/619857fd1ec4f351376ffcaaec20acc9aae9486f
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Yosry-Ahmed/bpf-rstat-cgroup-hierarchical-stats/20220611-034720
git checkout 619857fd1ec4f351376ffcaaec20acc9aae9486f
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash kernel/bpf/ kernel/cgroup/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

In file included from kernel/bpf/cgroup_iter.c:9:
kernel/bpf/../cgroup/cgroup-internal.h:78:41: error: field 'iter' has incomplete type
78 | struct css_task_iter iter;
| ^~~~
kernel/bpf/../cgroup/cgroup-internal.h: In function 'cgroup_is_dead':
kernel/bpf/../cgroup/cgroup-internal.h:188:22: error: invalid use of undefined type 'const struct cgroup'
188 | return !(cgrp->self.flags & CSS_ONLINE);
| ^~
kernel/bpf/../cgroup/cgroup-internal.h:188:37: error: 'CSS_ONLINE' undeclared (first use in this function); did you mean 'N_ONLINE'?
188 | return !(cgrp->self.flags & CSS_ONLINE);
| ^~~~~~~~~~
| N_ONLINE
kernel/bpf/../cgroup/cgroup-internal.h:188:37: note: each undeclared identifier is reported only once for each function it appears in
kernel/bpf/../cgroup/cgroup-internal.h: In function 'notify_on_release':
kernel/bpf/../cgroup/cgroup-internal.h:193:25: error: 'CGRP_NOTIFY_ON_RELEASE' undeclared (first use in this function)
193 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
| ^~~~~~~~~~~~~~~~~~~~~~
kernel/bpf/../cgroup/cgroup-internal.h:193:54: error: invalid use of undefined type 'const struct cgroup'
193 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
| ^~
kernel/bpf/../cgroup/cgroup-internal.h: In function 'put_css_set':
kernel/bpf/../cgroup/cgroup-internal.h:207:39: error: invalid use of undefined type 'struct css_set'
207 | if (refcount_dec_not_one(&cset->refcount))
| ^~
kernel/bpf/../cgroup/cgroup-internal.h: In function 'get_css_set':
kernel/bpf/../cgroup/cgroup-internal.h:220:27: error: invalid use of undefined type 'struct css_set'
220 | refcount_inc(&cset->refcount);
| ^~
kernel/bpf/../cgroup/cgroup-internal.h: At top level:
kernel/bpf/../cgroup/cgroup-internal.h:284:22: error: array type has incomplete element type 'struct cftype'
284 | extern struct cftype cgroup1_base_files[];
| ^~~~~~~~~~~~~~~~~~
kernel/bpf/cgroup_iter.c: In function 'cgroup_iter_seq_start':
kernel/bpf/cgroup_iter.c:55:24: error: implicit declaration of function 'css_next_descendant_pre' [-Werror=implicit-function-declaration]
55 | return css_next_descendant_pre(NULL, p->start_css);
| ^~~~~~~~~~~~~~~~~~~~~~~
>> kernel/bpf/cgroup_iter.c:55:24: warning: returning 'int' from a function with return type 'void *' makes pointer from integer without a cast [-Wint-conversion]
55 | return css_next_descendant_pre(NULL, p->start_css);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/bpf/cgroup_iter.c:57:24: error: implicit declaration of function 'css_next_descendant_post' [-Werror=implicit-function-declaration]
57 | return css_next_descendant_post(NULL, p->start_css);
| ^~~~~~~~~~~~~~~~~~~~~~~~
kernel/bpf/cgroup_iter.c:57:24: warning: returning 'int' from a function with return type 'void *' makes pointer from integer without a cast [-Wint-conversion]
57 | return css_next_descendant_post(NULL, p->start_css);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/bpf/cgroup_iter.c: In function 'cgroup_iter_seq_next':
kernel/bpf/cgroup_iter.c:83:24: warning: returning 'int' from a function with return type 'void *' makes pointer from integer without a cast [-Wint-conversion]
83 | return css_next_descendant_pre(curr, p->start_css);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/bpf/cgroup_iter.c:85:24: warning: returning 'int' from a function with return type 'void *' makes pointer from integer without a cast [-Wint-conversion]
85 | return css_next_descendant_post(curr, p->start_css);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/bpf/cgroup_iter.c:87:28: error: invalid use of undefined type 'struct cgroup_subsys_state'
87 | return curr->parent;
| ^~
kernel/bpf/cgroup_iter.c: In function '__cgroup_iter_seq_show':
kernel/bpf/cgroup_iter.c:100:38: error: invalid use of undefined type 'struct cgroup_subsys_state'
100 | if (css && cgroup_is_dead(css->cgroup))
| ^~
kernel/bpf/cgroup_iter.c:104:31: error: invalid use of undefined type 'struct cgroup_subsys_state'
104 | ctx.cgroup = css ? css->cgroup : NULL;
| ^~
kernel/bpf/cgroup_iter.c: In function 'cgroup_iter_seq_init':
kernel/bpf/cgroup_iter.c:137:29: error: invalid use of undefined type 'struct cgroup'
137 | p->start_css = &cgrp->self;
| ^~
kernel/bpf/cgroup_iter.c: In function 'bpf_iter_attach_cgroup':
kernel/bpf/cgroup_iter.c:157:24: error: implicit declaration of function 'cgroup_get_from_fd'; did you mean 'cgroup_get_from_id'? [-Werror=implicit-function-declaration]
157 | cgrp = cgroup_get_from_fd(fd);
| ^~~~~~~~~~~~~~~~~~
| cgroup_get_from_id
>> kernel/bpf/cgroup_iter.c:157:22: warning: assignment to 'struct cgroup *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
157 | cgrp = cgroup_get_from_fd(fd);
| ^
kernel/bpf/cgroup_iter.c:159:24: error: implicit declaration of function 'cgroup_get_from_path'; did you mean 'cgroup_get_from_id'? [-Werror=implicit-function-declaration]
159 | cgrp = cgroup_get_from_path("/");
| ^~~~~~~~~~~~~~~~~~~~
| cgroup_get_from_id
kernel/bpf/cgroup_iter.c:159:22: warning: assignment to 'struct cgroup *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
159 | cgrp = cgroup_get_from_path("/");
| ^
kernel/bpf/cgroup_iter.c: In function 'bpf_iter_cgroup_show_fdinfo':
kernel/bpf/cgroup_iter.c:190:9: error: implicit declaration of function 'cgroup_path_ns'; did you mean 'cgroup_parent'? [-Werror=implicit-function-declaration]
190 | cgroup_path_ns(aux->cgroup.start, buf, PATH_MAX,
| ^~~~~~~~~~~~~~
| cgroup_parent
kernel/bpf/cgroup_iter.c: In function 'cgroup_iter_seq_next':
kernel/bpf/cgroup_iter.c:88:1: error: control reaches end of non-void function [-Werror=return-type]
88 | }
| ^
cc1: some warnings being treated as errors

vim +55 kernel/bpf/cgroup_iter.c

41
42 static void *cgroup_iter_seq_start(struct seq_file *seq, loff_t *pos)
43 {
44 struct cgroup_iter_priv *p = seq->private;
45
46 mutex_lock(&cgroup_mutex);
47
48 /* support only one session */
49 if (*pos > 0)
50 return NULL;
51
52 ++*pos;
53 p->terminate = false;
54 if (p->order == BPF_ITER_CGROUP_PRE)
> 55 return css_next_descendant_pre(NULL, p->start_css);
56 else if (p->order == BPF_ITER_CGROUP_POST)
57 return css_next_descendant_post(NULL, p->start_css);
58 else /* BPF_ITER_CGROUP_PARENT_UP */
59 return p->start_css;
60 }
61
62 static int __cgroup_iter_seq_show(struct seq_file *seq,
63 struct cgroup_subsys_state *css, int in_stop);
64
65 static void cgroup_iter_seq_stop(struct seq_file *seq, void *v)
66 {
67 /* pass NULL to the prog for post-processing */
68 if (!v)
69 __cgroup_iter_seq_show(seq, NULL, true);
70 mutex_unlock(&cgroup_mutex);
71 }
72
73 static void *cgroup_iter_seq_next(struct seq_file *seq, void *v, loff_t *pos)
74 {
75 struct cgroup_subsys_state *curr = (struct cgroup_subsys_state *)v;
76 struct cgroup_iter_priv *p = seq->private;
77
78 ++*pos;
79 if (p->terminate)
80 return NULL;
81
82 if (p->order == BPF_ITER_CGROUP_PRE)
83 return css_next_descendant_pre(curr, p->start_css);
84 else if (p->order == BPF_ITER_CGROUP_POST)
85 return css_next_descendant_post(curr, p->start_css);
86 else
87 return curr->parent;
88 }
89
90 static int __cgroup_iter_seq_show(struct seq_file *seq,
91 struct cgroup_subsys_state *css, int in_stop)
92 {
93 struct cgroup_iter_priv *p = seq->private;
94 struct bpf_iter__cgroup ctx;
95 struct bpf_iter_meta meta;
96 struct bpf_prog *prog;
97 int ret = 0;
98
99 /* cgroup is dead, skip this element */
100 if (css && cgroup_is_dead(css->cgroup))
101 return 0;
102
103 ctx.meta = &meta;
104 ctx.cgroup = css ? css->cgroup : NULL;
105 meta.seq = seq;
106 prog = bpf_iter_get_info(&meta, in_stop);
107 if (prog)
108 ret = bpf_iter_run_prog(prog, &ctx);
109
110 /* if prog returns > 0, terminate after this element. */
111 if (ret != 0)
112 p->terminate = true;
113
114 return 0;
115 }
116
117 static int cgroup_iter_seq_show(struct seq_file *seq, void *v)
118 {
119 return __cgroup_iter_seq_show(seq, (struct cgroup_subsys_state *)v,
120 false);
121 }
122
123 static const struct seq_operations cgroup_iter_seq_ops = {
124 .start = cgroup_iter_seq_start,
125 .next = cgroup_iter_seq_next,
126 .stop = cgroup_iter_seq_stop,
127 .show = cgroup_iter_seq_show,
128 };
129
130 BTF_ID_LIST_SINGLE(bpf_cgroup_btf_id, struct, cgroup)
131
132 static int cgroup_iter_seq_init(void *priv, struct bpf_iter_aux_info *aux)
133 {
134 struct cgroup_iter_priv *p = (struct cgroup_iter_priv *)priv;
135 struct cgroup *cgrp = aux->cgroup.start;
136
137 p->start_css = &cgrp->self;
138 p->terminate = false;
139 p->order = aux->cgroup.order;
140 return 0;
141 }
142
143 static const struct bpf_iter_seq_info cgroup_iter_seq_info = {
144 .seq_ops = &cgroup_iter_seq_ops,
145 .init_seq_private = cgroup_iter_seq_init,
146 .seq_priv_size = sizeof(struct cgroup_iter_priv),
147 };
148
149 static int bpf_iter_attach_cgroup(struct bpf_prog *prog,
150 union bpf_iter_link_info *linfo,
151 struct bpf_iter_aux_info *aux)
152 {
153 int fd = linfo->cgroup.cgroup_fd;
154 struct cgroup *cgrp;
155
156 if (fd)
> 157 cgrp = cgroup_get_from_fd(fd);
158 else /* walk the entire hierarchy by default. */
159 cgrp = cgroup_get_from_path("/");
160
161 if (IS_ERR(cgrp))
162 return PTR_ERR(cgrp);
163
164 aux->cgroup.start = cgrp;
165 aux->cgroup.order = linfo->cgroup.traversal_order;
166 return 0;
167 }
168

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