linux-kernel - Re: [PATCH] usb: musb: mark PM functions as __maybe

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Message-ID: <7174247.C7pj70tUDp@wuerfel>
Date:   Mon, 28 Nov 2016 11:54:54 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Bin Liu <b-liu@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Tony Lindgren <tony@...mide.com>,
        Felipe Balbi <balbi@...nel.org>,
        Johan Hovold <johan@...nel.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        USB list <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: musb: mark PM functions as __maybe_unused

On Monday, November 28, 2016 11:51:37 AM CET Geert Uytterhoeven wrote:
> On Tue, Nov 22, 2016 at 3:30 PM, Arnd Bergmann <arnd@...db.de> wrote:
> > Building without CONFIG_PM causes a harmless warning:
> >
> > drivers/usb/musb/musb_core.c:2041:12: error: ‘musb_run_resume_work’ defined but not used [-Werror=unused-function]
> >
> > Removing the #ifdef around the PM code and instead marking the suspend/resume
> > functions as __maybe_unused will do the right thing without warning.
> >
> > Fixes: ea2f35c01d5e ("usb: musb: Fix sleeping function called from invalid context for hdrc glue")
> > Signed-off-by: Arnd Bergmann <arnd@...db.de>
> 
> linux-m68k-allmodconfig$ bloat-o-meter drivers/usb/musb/musb_core.o{.orig,}
> add/remove: 8/0 grow/shrink: 0/0 up/down: 2344/0 (2344)
> function                                     old     new   delta
> musb_restore_context                           -     892    +892
> musb_save_context                              -     690    +690
> musb_run_resume_work                           -     190    +190
> musb_resume                                    -     182    +182
> musb_runtime_resume                            -     148    +148
> musb_suspend                                   -     114    +114
> musb_dev_pm_ops                                -      92     +92
> musb_runtime_suspend                           -      36     +36
> Total: Before=13091, After=15435, chg +17.91%

Well, in allmodconfig, you have CONFIG_PM enabled, so this is not
dead code but actually does what was intended (though possibly
not written as efficiently as it could have been).

In a configuration without CONFIG_PM, there should ideally be
no added code.

	Arnd