linux-kernel - Re: [PATCH 2/2] binderfs: remove separate device

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Date:   Wed, 30 Jan 2019 18:01:02 +0100
From:   Christian Brauner <christian@...uner.io>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     tkjos@...roid.com, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org, arve@...roid.com, maco@...roid.com,
        joel@...lfernandes.org, tkjos@...gle.com
Subject: Re: [PATCH 2/2] binderfs: remove separate device_initcall()

On Wed, Jan 30, 2019 at 03:24:12PM +0100, Greg KH wrote:
> On Wed, Jan 23, 2019 at 12:41:16PM +0100, Christian Brauner wrote:
> > binderfs should not have a separate device_initcall(). When a kernel is
> > compiled with CONFIG_ANDROID_BINDERFS register the filesystem alongside
> > CONFIG_ANDROID_IPC. This use-case is especially sensible when users specify
> > CONFIG_ANDROID_IPC=y, CONFIG_ANDROID_BINDERFS=y and
> > ANDROID_BINDER_DEVICES="".
> > When CONFIG_ANDROID_BINDERFS=n then this always succeeds so there's no
> > regression potential for legacy workloads.
> > 
> > Signed-off-by: Christian Brauner <christian@...uner.io>
> > ---
> >  drivers/android/binder.c          | 4 ++++
> >  drivers/android/binder_internal.h | 9 +++++++++
> >  drivers/android/binderfs.c        | 4 +---
> >  3 files changed, 14 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> > index cdfc87629efb..751d76173f81 100644
> > --- a/drivers/android/binder.c
> > +++ b/drivers/android/binder.c
> > @@ -5915,6 +5915,10 @@ static int __init binder_init(void)
> >  			goto err_init_binder_device_failed;
> >  	}
> >  
> > +	ret = init_binderfs();
> > +	if (ret)
> > +		goto err_init_binder_device_failed;
> > +
> >  	return ret;
> >  
> >  err_init_binder_device_failed:
> > diff --git a/drivers/android/binder_internal.h b/drivers/android/binder_internal.h
> > index 7fb97f503ef2..045b3e42d98b 100644
> > --- a/drivers/android/binder_internal.h
> > +++ b/drivers/android/binder_internal.h
> > @@ -46,4 +46,13 @@ static inline bool is_binderfs_device(const struct inode *inode)
> >  }
> >  #endif
> >  
> > +#ifdef CONFIG_ANDROID_BINDERFS
> > +extern int __init init_binderfs(void);
> > +#else
> > +static inline int __init init_binderfs(void)
> > +{
> > +	return 0;
> > +}
> > +#endif
> > +
> >  #endif /* _LINUX_BINDER_INTERNAL_H */
> > diff --git a/drivers/android/binderfs.c b/drivers/android/binderfs.c
> > index 7a550104a722..e773f45d19d9 100644
> > --- a/drivers/android/binderfs.c
> > +++ b/drivers/android/binderfs.c
> > @@ -550,7 +550,7 @@ static struct file_system_type binder_fs_type = {
> >  	.fs_flags	= FS_USERNS_MOUNT,
> >  };
> >  
> > -static int __init init_binderfs(void)
> > +int __init init_binderfs(void)
> >  {
> >  	int ret;
> >  
> > @@ -568,5 +568,3 @@ static int __init init_binderfs(void)
> >  
> >  	return ret;
> >  }
> > -
> > -device_initcall(init_binderfs);
> 
> I get a build warning when applying this patch :(

Hm, I can't reproduce that build error with this patch applied to what
you currently have in char-misc-linus. :(
Any chance you can give me the config that produced this warning?
I tried with CONFIG_BINDERFS=y and CONFIG_BINDERFS=n.

Thanks!
Christian