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Message-ID: <f562cf52-6251-25cf-7b33-a2135cdcc313@bytedance.com>
Date:   Mon, 24 Jul 2023 20:46:44 +0800
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Subject: Re: [PATCH] kernfs: add stub helper for kernfs_generic_poll()
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To:     Arnd Bergmann <arnd@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Tejun Heo <tj@kernel.org>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Suren Baghdasaryan <surenb@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>
Cc:     Arnd Bergmann <arnd@arndb.de>, linux-kernel@vger.kernel.org
References: <20230724121823.1357562-1-arnd@kernel.org>
From:   Chengming Zhou <zhouchengming@bytedance.com>
In-Reply-To: <20230724121823.1357562-1-arnd@kernel.org>
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On 2023/7/24 20:18, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> In some randconfig builds, kernfs ends up being disabled, so there is no prototype
> for kernfs_generic_poll()
> 
> In file included from kernel/sched/build_utility.c:97:
> kernel/sched/psi.c:1479:3: error: implicit declaration of function 'kernfs_generic_poll' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
>                 kernfs_generic_poll(t->of, wait);
>                 ^
> 
> Add a stub helper for it, as we have it for other kernfs functions.
> 
> Fixes: aff037078ecae ("sched/psi: use kernfs polling functions for PSI trigger polling")
> Fixes: 147e1a97c4a0b ("fs: kernfs: add poll file operation")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> While the stub was always missing, this only caused problems now that sched/psi.c
> calls it unconditionally. The patch that caused it was already merged into v6.5-rc2
> ---
>  include/linux/kernfs.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
> index 73f5c120def88..2a36f3218b510 100644
> --- a/include/linux/kernfs.h
> +++ b/include/linux/kernfs.h
> @@ -550,6 +550,10 @@ static inline int kernfs_setattr(struct kernfs_node *kn,
>  				 const struct iattr *iattr)
>  { return -ENOSYS; }
>  
> +static inline __poll_t kernfs_generic_poll(struct kernfs_open_file *of,
> +					   struct poll_table_struct *pt)
> +{ return -ENOSYS; }
> +
>  static inline void kernfs_notify(struct kernfs_node *kn) { }
>  
>  static inline int kernfs_xattr_get(struct kernfs_node *kn, const char *name,

Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>

Thanks.