| Message ID | 20201218185032.2464558-4-jonathan.lemon@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | bpf: increment and use correct thread iterator | expand |
On Fri, Dec 18, 2020 at 12:47 PM Jonathan Lemon <jonathan.lemon@gmail.com> wrote: > > From: Jonathan Lemon <bsd@fb.com> > > Only obtain the task reference count at the end of the RCU section > instead of repeatedly obtaining/releasing it when iterating though > a thread group. > > Jump to the correct branch when it is known that the task is NULL. > > Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com> > --- Acked-by: Andrii Nakryiko <andrii@kernel.org> > kernel/bpf/task_iter.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c > index dc4007f1843b..598a8d7da5bf 100644 > --- a/kernel/bpf/task_iter.c > +++ b/kernel/bpf/task_iter.c > @@ -33,7 +33,7 @@ static struct task_struct *task_seq_get_next(struct pid_namespace *ns, > pid = find_ge_pid(*tid, ns); > if (pid) { > *tid = pid_nr_ns(pid, ns); > - task = get_pid_task(pid, PIDTYPE_PID); > + task = pid_task(pid, PIDTYPE_PID); > if (!task) { > ++*tid; > goto retry; > @@ -44,6 +44,7 @@ static struct task_struct *task_seq_get_next(struct pid_namespace *ns, > ++*tid; > goto retry; > } > + get_task_struct(task); > } > rcu_read_unlock(); > > @@ -148,12 +149,12 @@ task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info) > * it held a reference to the task/files_struct/file. > * Otherwise, it does not hold any reference. > */ > -again: > if (info->task) { > curr_task = info->task; > curr_files = info->files; > curr_fd = info->fd; > } else { > +again: > curr_task = task_seq_get_next(ns, &curr_tid, true); > if (!curr_task) { > info->task = NULL; > -- > 2.24.1 >
diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c index dc4007f1843b..598a8d7da5bf 100644 --- a/kernel/bpf/task_iter.c +++ b/kernel/bpf/task_iter.c @@ -33,7 +33,7 @@ static struct task_struct *task_seq_get_next(struct pid_namespace *ns, pid = find_ge_pid(*tid, ns); if (pid) { *tid = pid_nr_ns(pid, ns); - task = get_pid_task(pid, PIDTYPE_PID); + task = pid_task(pid, PIDTYPE_PID); if (!task) { ++*tid; goto retry; @@ -44,6 +44,7 @@ static struct task_struct *task_seq_get_next(struct pid_namespace *ns, ++*tid; goto retry; } + get_task_struct(task); } rcu_read_unlock(); @@ -148,12 +149,12 @@ task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info) * it held a reference to the task/files_struct/file. * Otherwise, it does not hold any reference. */ -again: if (info->task) { curr_task = info->task; curr_files = info->files; curr_fd = info->fd; } else { +again: curr_task = task_seq_get_next(ns, &curr_tid, true); if (!curr_task) { info->task = NULL;