Re: [PATCH 11/17] bpf/task_iter: In task_file_seq_get_next use fnext_task

kernel test robot
2020-08-18T05:51:11Z

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Hi "Eric,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on bpf/master]
[also build test WARNING on linus/master v5.9-rc1 next-20200817]
[cannot apply to bpf-next/master linux/master]
[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]

url: https://github.com/0day-ci/linux/commits/Eric-W-Biederman/exec-Move-unshare_files-to-fix-posix-file-locking-during-exec/20200818-061552
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git master
config: i386-randconfig-m021-20200818 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0

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

smatch warnings:
kernel/bpf/task_iter.c:162 task_file_seq_get_next() warn: ignoring unreachable code.

# https://github.com/0day-ci/linux/commit/66f80aa453b17f8932b42e18265dba5fdb32490e
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Eric-W-Biederman/exec-Move-unshare_files-to-fix-posix-file-locking-during-exec/20200818-061552
git checkout 66f80aa453b17f8932b42e18265dba5fdb32490e
vim +162 kernel/bpf/task_iter.c

128
129 static struct file *
130 task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info,
131 struct task_struct **task)
132 {
133 struct pid_namespace *ns = info->common.ns;
134 u32 curr_tid = info->tid;
135 struct task_struct *curr_task;
136 unsigned int curr_fd = info->fd;
137
138 /* If this function returns a non-NULL file object,
139 * it held a reference to the task/file.
140 * Otherwise, it does not hold any reference.
141 */
142 again:
143 if (*task) {
144 curr_task = *task;
145 curr_fd = info->fd;
146 } else {
147 curr_task = task_seq_get_next(ns, &curr_tid);
148 if (!curr_task)
149 return NULL;
150
151 /* set *task and info->tid */
152 *task = curr_task;
153 if (curr_tid == info->tid) {
154 curr_fd = info->fd;
155 } else {
156 info->tid = curr_tid;
157 curr_fd = 0;
158 }
159 }
160
161 rcu_read_lock();
> 162 for (;; curr_fd++) {
163 struct file *f;
164
165 f = fnext_task(curr_task, &curr_fd);
166 if (!f)
167 break;
168
169 /* set info->fd */
170 info->fd = curr_fd;
171 get_file(f);
172 rcu_read_unlock();
173 return f;
174 }
175
176 /* the current task is done, go to the next task */
177 rcu_read_unlock();
178 put_task_struct(curr_task);
179 *task = NULL;
180 info->fd = 0;
181 curr_tid = ++(info->tid);
182 goto again;
183 }
184

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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