bpf: Simplify task_file_seq_get_next()

Simplify task_file_seq_get_next() by removing two in/out arguments: task
and fstruct. Use info->task and info->files instead.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20201120002833.2481110-1-songliubraving@fb.com

diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
index 1fdb2fc..0458a40 100644 (file)
--- a/kernel/bpf/task_iter.c
+++ b/kernel/bpf/task_iter.c
@@ -136,8 +136,7 @@ struct bpf_iter_seq_task_file_info {
 };
 
 static struct file *
-task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info,
-                      struct task_struct **task, struct files_struct **fstruct)
+task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info)
 {
        struct pid_namespace *ns = info->common.ns;
        u32 curr_tid = info->tid, max_fds;
@@ -150,14 +149,17 @@ task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info,
         * Otherwise, it does not hold any reference.
         */
 again:
-       if (*task) {
-               curr_task = *task;
-               curr_files = *fstruct;
+       if (info->task) {
+               curr_task = info->task;
+               curr_files = info->files;
                curr_fd = info->fd;
        } else {
                curr_task = task_seq_get_next(ns, &curr_tid, true);
-               if (!curr_task)
+               if (!curr_task) {
+                       info->task = NULL;
+                       info->files = NULL;
                        return NULL;
+               }
 
                curr_files = get_files_struct(curr_task);
                if (!curr_files) {
@@ -167,9 +169,8 @@ again:
                        goto again;
                }
 
-               /* set *fstruct, *task and info->tid */
-               *fstruct = curr_files;
-               *task = curr_task;
+               info->files = curr_files;
+               info->task = curr_task;
                if (curr_tid == info->tid) {
                        curr_fd = info->fd;
                } else {
@@ -199,8 +200,8 @@ again:
        rcu_read_unlock();
        put_files_struct(curr_files);
        put_task_struct(curr_task);
-       *task = NULL;
-       *fstruct = NULL;
+       info->task = NULL;
+       info->files = NULL;
        info->fd = 0;
        curr_tid = ++(info->tid);
        goto again;
@@ -209,21 +210,13 @@ again:
 static void *task_file_seq_start(struct seq_file *seq, loff_t *pos)
 {
        struct bpf_iter_seq_task_file_info *info = seq->private;
-       struct files_struct *files = NULL;
-       struct task_struct *task = NULL;
        struct file *file;
 
-       file = task_file_seq_get_next(info, &task, &files);
-       if (!file) {
-               info->files = NULL;
-               info->task = NULL;
-               return NULL;
-       }
-
-       if (*pos == 0)
+       info->task = NULL;
+       info->files = NULL;
+       file = task_file_seq_get_next(info);
+       if (file && *pos == 0)
                ++*pos;
-       info->task = task;
-       info->files = files;
 
        return file;
 }
@@ -231,24 +224,11 @@ static void *task_file_seq_start(struct seq_file *seq, loff_t *pos)
 static void *task_file_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
        struct bpf_iter_seq_task_file_info *info = seq->private;
-       struct files_struct *files = info->files;
-       struct task_struct *task = info->task;
-       struct file *file;
 
        ++*pos;
        ++info->fd;
        fput((struct file *)v);
-       file = task_file_seq_get_next(info, &task, &files);
-       if (!file) {
-               info->files = NULL;
-               info->task = NULL;
-               return NULL;
-       }
-
-       info->task = task;
-       info->files = files;
-
-       return file;
+       return task_file_seq_get_next(info);
 }
 
 struct bpf_iter__task_file {