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SubjectRe: [PATCH] kprobes: no need to check return value of debugfs_create functions
On Tue, 22 Jan 2019 16:21:46 +0100
Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:

> When calling debugfs functions, there is no need to ever check the
> return value. The function can work or not, but the code logic should
> never do something different based on this.
>
> Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Masami Hiramatsu <mhiramat@kernel.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> kernel/kprobes.c | 25 ++++++-------------------
> 1 file changed, 6 insertions(+), 19 deletions(-)
>
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index f4ddfdd2d07e..7287e7de2350 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -2566,33 +2566,20 @@ static const struct file_operations fops_kp = {
>
> static int __init debugfs_kprobe_init(void)
> {
> - struct dentry *dir, *file;
> + struct dentry *dir;
> unsigned int value = 1;
>
> dir = debugfs_create_dir("kprobes", NULL);
> - if (!dir)
> - return -ENOMEM;

Here, I think IS_ERR(dir) is OK for debugfs_create_file(),
but dir == NULL has different meaning. I think we'd better
keep this check. (I see, -ENOMEM will be no good...)

Thank you,

>
> - file = debugfs_create_file("list", 0400, dir, NULL,
> - &debugfs_kprobes_operations);
> - if (!file)
> - goto error;
> + debugfs_create_file("list", 0400, dir, NULL,
> + &debugfs_kprobes_operations);
>
> - file = debugfs_create_file("enabled", 0600, dir,
> - &value, &fops_kp);
> - if (!file)
> - goto error;
> + debugfs_create_file("enabled", 0600, dir, &value, &fops_kp);
>
> - file = debugfs_create_file("blacklist", 0400, dir, NULL,
> - &debugfs_kprobe_blacklist_ops);
> - if (!file)
> - goto error;
> + debugfs_create_file("blacklist", 0400, dir, NULL,
> + &debugfs_kprobe_blacklist_ops);
>
> return 0;
> -
> -error:
> - debugfs_remove(dir);
> - return -ENOMEM;
> }
>
> late_initcall(debugfs_kprobe_init);
> --
> 2.20.1
>


--
Masami Hiramatsu <mhiramat@kernel.org>

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