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From: Hans de Goede <hdegoede@redhat.com>
To: Randy Dunlap <rdunlap@infradead.org>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Linux-Next Mailing List <linux-next@vger.kernel.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: linux-next: Tree for Oct 31 (vboxguest)
Date: Wed, 31 Oct 2018 17:50:47 +0100	[thread overview]
Message-ID: <560c85c8-1ee2-31b0-3148-a08f56a25a2e@redhat.com> (raw)
In-Reply-To: <661e44c7-396a-6d58-efa7-ed292f2677c6@infradead.org>

Hi,

On 31-10-18 16:51, Randy Dunlap wrote:
> On 10/30/18 8:59 PM, Stephen Rothwell wrote:
>> Hi all,
>>
>> Please do not add any v4.21/v5.1 code to your linux-next included trees
>> until after the merge window closes.
>>
>> Changes since 20181030:
>>
> 
> 
> on i386:
> 
> ld: drivers/virt/vboxguest/vboxguest_core.o: in function `vbg_ioctl_hgcm_call':
> vboxguest_core.c:(.text+0x212b): undefined reference to `vbg_hgcm_call32'

Are you perhaps using weird compiler options?

This call should be optimized out on i386 (and we rely on calls being
removed be dead code elimination to avoid #ifdefs in various places,
iow this is a normal thing to rely on) :

First we have:

	bool f32bit = false;

...

         switch (req_no_size) {
#ifdef CONFIG_COMPAT
         case VBG_IOCTL_HGCM_CALL_32(0):
                 f32bit = true;
                 /* Fall through */
#endif
         case VBG_IOCTL_HGCM_CALL(0):
                 return vbg_ioctl_hgcm_call(gdev, session, f32bit, data);
	}

And then we also have:

static int vbg_ioctl_hgcm_call(struct vbg_dev *gdev,
                                struct vbg_session *session, bool f32bit,
                                struct vbg_ioctl_hgcm_call *call)
{
	...

         if (f32bit)
                 ret = vbg_hgcm_call32(gdev, client_id,
                                       call->function, call->timeout_ms,
                                       VBG_IOCTL_HGCM_CALL_PARMS32(call),
                                       call->parm_count, &call->hdr.rc);
         else
                 ret = vbg_hgcm_call(gdev, client_id,
                                     call->function, call->timeout_ms,
                                     VBG_IOCTL_HGCM_CALL_PARMS(call),
                                     call->parm_count, &call->hdr.rc);
}

So on i386 CONFIG_COMPAT is never set, this f32bit is a 0 const
and the compiler removes the if branch of the if ... else ...

This has been upstream like this since 4.16 without any problems sofar.

Regards,

Hans

  reply	other threads:[~2018-10-31 16:50 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-31  3:59 linux-next: Tree for Oct 31 Stephen Rothwell
2018-10-31 15:51 ` linux-next: Tree for Oct 31 (vboxguest) Randy Dunlap
2018-10-31 16:50   ` Hans de Goede [this message]
2018-10-31 19:06     ` Randy Dunlap
2018-10-31 21:41   ` Arnd Bergmann
2018-10-31 21:45     ` Randy Dunlap
2018-11-01  3:32     ` Masahiro Yamada
2018-11-01 14:29       ` Changbin Du
2018-11-02  8:25         ` Masahiro Yamada
2018-11-02 15:54           ` Arnd Bergmann
2018-11-02 23:59             ` Changbin Du
2018-11-04  2:43             ` Masahiro Yamada
2018-11-04 23:38               ` Changbin Du
2018-11-05  3:00                 ` Masahiro Yamada
2018-11-02 23:59           ` Changbin Du

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