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Date:   Fri, 22 Nov 2019 16:20:25 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Kusanagi Kouichi <slash@ac.auone-net.jp>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] debugfs: Fix !DEBUG_FS debugfs_create_automount
Message-ID: <20191122162025.GC26530@ZenIV.linux.org.uk>
References: <20191121102021787.MLMY.25002.ppp.dion.ne.jp@dmta0003.auone-net.jp>
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On Thu, Nov 21, 2019 at 07:20:21PM +0900, Kusanagi Kouichi wrote:
> If DEBUG_FS=n, compile fails with the following error:
> 
> kernel/trace/trace.c: In function 'tracing_init_dentry':
> kernel/trace/trace.c:8658:9: error: passing argument 3 of 'debugfs_create_automount' from incompatible pointer type [-Werror=incompatible-pointer-types]
>  8658 |         trace_automount, NULL);
>       |         ^~~~~~~~~~~~~~~
>       |         |
>       |         struct vfsmount * (*)(struct dentry *, void *)
> In file included from kernel/trace/trace.c:24:
> ./include/linux/debugfs.h:206:25: note: expected 'struct vfsmount * (*)(void *)' but argument is of type 'struct vfsmount * (*)(struct dentry *, void *)'
>   206 |      struct vfsmount *(*f)(void *),
>       |      ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~

ACK.  I'd probably add something along the lines of "the stub for
debugfs_create_automount() used in !DEBUG_FS configs is misdeclared -
its callback argument (unused by the stub) has the wrong type.
Get the stub in sync with the real debugfs_create_automount()."
to commit message.