linux-kernel - Re: [PATCH v3 1/2] binder: Add default binder devices through binderfs when configured

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Message-ID: <20190809182216.5xzx6tss6fh42mso@wittgenstein>
Date:   Fri, 9 Aug 2019 20:22:17 +0200
From:   Christian Brauner <christian.brauner@...ntu.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Hridya Valsaraju <hridya@...gle.com>,
        Arve Hjønnevåg <arve@...roid.com>,
        Todd Kjos <tkjos@...roid.com>,
        Martijn Coenen <maco@...roid.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        kernel-team@...roid.com
Subject: Re: [PATCH v3 1/2] binder: Add default binder devices through
 binderfs when configured

On Fri, Aug 09, 2019 at 04:50:16PM +0200, Greg Kroah-Hartman wrote:
> On Thu, Aug 08, 2019 at 03:27:25PM -0700, Hridya Valsaraju wrote:
> > Currently, since each binderfs instance needs its own
> > private binder devices, every time a binderfs instance is
> > mounted, all the default binder devices need to be created
> > via the BINDER_CTL_ADD IOCTL.
> 
> Wasn't that a design goal of binderfs?

Sure, but if you solely rely binderfs to be used to provide binder
devices having them pre-created on each mount makes quite some sense,
imho.

> 
> > This patch aims to
> > add a solution to automatically create the default binder
> > devices for each binderfs instance that gets mounted.
> > To achieve this goal, when CONFIG_ANDROID_BINDERFS is set,
> > the default binder devices specified by CONFIG_ANDROID_BINDER_DEVICES
> > are created in each binderfs instance instead of global devices
> > being created by the binder driver.
> 
> This is going to change how things work today, what is going to break
> because of this change?
> 
> I don't object to this, except for the worry of changing the default
> behavior.

This is something that Hridya and Todd can speak better to given that
they suggested this change. :)
>From my perspective, binderfs binder devices and the regular binder
driver are mostly used mutually exclusive in practice atm so that this
change has little chance of breaking anyone.

Now I really need to go back to vacation time - which I suck at
apparently. :)

Christian