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bpf: bpf_iter_task_next: use next_task(kit->task) rather than next_task(kit->pos) 

This looks more clear and simplifies the code. While at it, remove the
unnecessary initialization of pos/task at the start of bpf_iter_task_new().

Note that we can even kill kit->task, we can just use pos->group_leader,
but I don't understand the BUILD_BUG_ON() checks in bpf_iter_task_new().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20231114163239.GA903@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Oleg Nesterov 2023-11-14 17:32:39 +01:00 committed by Alexei Starovoitov
parent 5a34f9dabd
commit ac8148d957
1 changed files with 5 additions and 9 deletions
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14
kernel/bpf/task_iter.c
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@ -978,7 +978,6 @@ __bpf_kfunc int bpf_iter_task_new(struct bpf_iter_task *it,
BUILD_BUG_ON(__alignof__(struct bpf_iter_task_kern) !=
__alignof__(struct bpf_iter_task));
kit->task = kit->pos = NULL;
switch (flags) {
case BPF_TASK_ITER_ALL_THREADS:
case BPF_TASK_ITER_ALL_PROCS:
@ -1016,18 +1015,15 @@ __bpf_kfunc struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it)
goto get_next_task;
kit->pos = __next_thread(kit->pos);
if (!kit->pos) {
if (flags == BPF_TASK_ITER_PROC_THREADS)
return pos;
kit->pos = kit->task;
} else
if (kit->pos || flags == BPF_TASK_ITER_PROC_THREADS)
return pos;
get_next_task:
kit->pos = next_task(kit->pos);
kit->task = kit->pos;
if (kit->pos == &init_task)
kit->task = next_task(kit->task);
if (kit->task == &init_task)
kit->pos = NULL;
else
kit->pos = kit->task;
return pos;
}