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bpf: Avoid visit same object multiple times 

Currently when traversing all tasks, the next tid
is always increased by one. This may result in
visiting the same task multiple times in a
pid namespace.

This patch fixed the issue by seting the next
tid as pid_nr_ns(pid, ns) + 1, similar to
funciton next_tgid().

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Link: https://lore.kernel.org/bpf/20200818222310.2181500-1-yhs@fb.com
This commit is contained in:
Yonghong Song 2020-08-18 15:23:10 -07:00 committed by Alexei Starovoitov
parent e679654a70
commit e60572b8d4
1 changed files with 2 additions and 1 deletions
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3
kernel/bpf/task_iter.c
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@ -29,8 +29,9 @@ static struct task_struct *task_seq_get_next(struct pid_namespace *ns,
rcu_read_lock();
retry:
pid = idr_get_next(&ns->idr, tid);
pid = find_ge_pid(*tid, ns);
if (pid) {
*tid = pid_nr_ns(pid, ns);
task = get_pid_task(pid, PIDTYPE_PID);
if (!task) {
++*tid;