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Date: Sat, 4 Apr 2020 17:50:40 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Taehee Yoo <ap420073@...il.com>
Cc: davem@...emloft.net, kuba@...nel.org, rafael@...nel.org,
j.vosburgh@...il.com, vfalico@...il.com, andy@...yhouse.net,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
mitch.a.williams@...el.com
Subject: Re: [PATCH net v2 1/3] class: add class_has_file_ns() helper function
On Sat, Apr 04, 2020 at 02:18:27PM +0000, Taehee Yoo wrote:
> The new helper function is to check whether the class file is existing
> or not. This function will be used by networking stack to
> check "/sys/class/net/*" file.
>
> Reported-by: syzbot+830c6dbfc71edc4f0b8f@...kaller.appspotmail.com
> Fixes: b76cdba9cdb2 ("[PATCH] bonding: add sysfs functionality to bonding (large)")
> Signed-off-by: Taehee Yoo <ap420073@...il.com>
> ---
>
> v1 -> v2:
> - Implement class_has_file_ns() instead of class_find_and_get_file_ns().
> - Change headline.
> - Add kernel documentation comment.
>
> drivers/base/class.c | 22 ++++++++++++++++++++++
> include/linux/device/class.h | 3 ++-
> 2 files changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/class.c b/drivers/base/class.c
> index bcd410e6d70a..a2f2787f6aa7 100644
> --- a/drivers/base/class.c
> +++ b/drivers/base/class.c
> @@ -105,6 +105,28 @@ void class_remove_file_ns(struct class *cls, const struct class_attribute *attr,
> sysfs_remove_file_ns(&cls->p->subsys.kobj, &attr->attr, ns);
> }
>
> +/**
> + * class_has_file_ns - check whether file is existing or not
> + * @cls: the compatibility class
> + * @name: name to look for
> + * @ns: the namespace tag to use
> + */
> +bool class_has_file_ns(struct class *cls, const char *name,
> + const void *ns)
Why would you use this? And what happens if the file shows up, or goes
away, instantly after this call is made?
This feels very broken.
greg k-h
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