bpf: remove unnecessary loop in task_file_seq_get_next()

[PATCH bpf-next] bpf: remove unnecessary loop in task_file_seq_get_next()

Posted by Dan Carpenter 1 year, 7 months ago

After commit 0ede61d8589c ("file: convert to SLAB_TYPESAFE_BY_RCU") this
loop always iterates exactly one time.  Delete the for statement and pull
the code in a tab.

Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
 kernel/bpf/task_iter.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
index ec4e97c61eef..02aa9db8d796 100644
--- a/kernel/bpf/task_iter.c
+++ b/kernel/bpf/task_iter.c
@@ -261,6 +261,7 @@ task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info)
 	u32 saved_tid = info->tid;
 	struct task_struct *curr_task;
 	unsigned int curr_fd = info->fd;
+	struct file *f;
 
 	/* If this function returns a non-NULL file object,
 	 * it held a reference to the task/file.
@@ -286,12 +287,8 @@ task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info)
 	}
 
 	rcu_read_lock();
-	for (;; curr_fd++) {
-		struct file *f;
-		f = task_lookup_next_fdget_rcu(curr_task, &curr_fd);
-		if (!f)
-			break;
-
+	f = task_lookup_next_fdget_rcu(curr_task, &curr_fd);
+	if (f) {
 		/* set info->fd */
 		info->fd = curr_fd;
 		rcu_read_unlock();
-- 
2.43.0

Re: [PATCH bpf-next] bpf: remove unnecessary loop in task_file_seq_get_next()

Posted by Yonghong Song 1 year, 7 months ago

On 7/4/24 8:19 AM, Dan Carpenter wrote:
> After commit 0ede61d8589c ("file: convert to SLAB_TYPESAFE_BY_RCU") this
> loop always iterates exactly one time.  Delete the for statement and pull
> the code in a tab.
>
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>

LGTM. Thanks for the cleanup.

Acked-by: Yonghong Song <yonghong.song@linux.dev>

Re: [PATCH bpf-next] bpf: remove unnecessary loop in task_file_seq_get_next()

Posted by Christian Brauner 1 year, 7 months ago

On Thu, Jul 04, 2024 at 10:19:19AM GMT, Dan Carpenter wrote:
> After commit 0ede61d8589c ("file: convert to SLAB_TYPESAFE_BY_RCU") this
> loop always iterates exactly one time.  Delete the for statement and pull
> the code in a tab.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> ---

Reviewed-by: Christian Brauner <brauner@kernel.org>

Re: [PATCH bpf-next] bpf: remove unnecessary loop in task_file_seq_get_next()

Posted by Jiri Olsa 1 year, 7 months ago

On Thu, Jul 04, 2024 at 10:19:19AM -0500, Dan Carpenter wrote:
> After commit 0ede61d8589c ("file: convert to SLAB_TYPESAFE_BY_RCU") this
> loop always iterates exactly one time.  Delete the for statement and pull
> the code in a tab.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>

lgtm

Acked-by: Jiri Olsa <jolsa@kernel.org>

jirka

> ---
>  kernel/bpf/task_iter.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
> index ec4e97c61eef..02aa9db8d796 100644
> --- a/kernel/bpf/task_iter.c
> +++ b/kernel/bpf/task_iter.c
> @@ -261,6 +261,7 @@ task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info)
>  	u32 saved_tid = info->tid;
>  	struct task_struct *curr_task;
>  	unsigned int curr_fd = info->fd;
> +	struct file *f;
>  
>  	/* If this function returns a non-NULL file object,
>  	 * it held a reference to the task/file.
> @@ -286,12 +287,8 @@ task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info)
>  	}
>  
>  	rcu_read_lock();
> -	for (;; curr_fd++) {
> -		struct file *f;
> -		f = task_lookup_next_fdget_rcu(curr_task, &curr_fd);
> -		if (!f)
> -			break;
> -
> +	f = task_lookup_next_fdget_rcu(curr_task, &curr_fd);
> +	if (f) {
>  		/* set info->fd */
>  		info->fd = curr_fd;
>  		rcu_read_unlock();
> -- 
> 2.43.0
>