Re: [PATCH 1/1] scsi: storvsc: Fix a build issue reported by kbuild test robot

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Fri, 2016-02-26 at 23:22 +0000, KY Srinivasan wrote:
> 
> > -----Original Message-----
> > From: James Bottomley [mailto:James.Bottomley@HansenPartnership.com
> > ]
> > Sent: Friday, February 26, 2016 2:25 PM
> > To: KY Srinivasan <kys@microsoft.com>; linux-kernel@vger.kernel.org
> > ;
> > devel@linuxdriverproject.org; ohering@suse.com;
> > jbottomley@parallels.com; hch@infradead.org; 
> > linux-scsi@vger.kernel.org;
> > apw@canonical.com; vkuznets@redhat.com; jasowang@redhat.com;
> > martin.petersen@oracle.com; hare@suse.de
> > Subject: Re: [PATCH 1/1] scsi: storvsc: Fix a build issue reported
> > by kbuild test
> > robot
> > 
> > On Fri, 2016-02-26 at 15:45 -0800, K. Y. Srinivasan wrote:
> > > tree:   
> > > https://na01.safelinks.protection.outlook.com/?url=https%3a%2
> > > f%2fgit.kernel.org%2fpub%2fscm%2flinux%2fkernel%2fgit%2ftorvalds%
> > > 2fli
> > > 
> > nux.git&data=01%7c01%7ckys%40microsoft.com%7ce2e0622715844b79ad71
> > 08d3
> > > 
> > 2796ec3c%7c72f988bf86f141af91ab2d7cd011db47%7c1&sdata=ubr4GbBaNS
> > %2ftO
> > > z%2buJBk0CL9N0UNG9x2TidLgy6Yovg4%3d master
> > > head:   03c21cb775a313f1ff19be59c5d02df3e3526471
> > > commit: dac582417bc449b1f7f572d3f1dd9d23eec15cc9 storvsc:
> > > Properly
> > > support Fibre Channel devices
> > > date:   3 weeks ago
> > > config: x86_64-randconfig-s3-01281016 (attached as .config)
> > > reproduce:
> > >         git checkout dac582417bc449b1f7f572d3f1dd9d23eec15cc9
> > >         # save the attached .config to linux build tree
> > >         make ARCH=x86_64
> > > 
> > > All errors (new ones prefixed by >>):
> > > 
> > >    drivers/built-in.o: In function `storvsc_remove':
> > > > > storvsc_drv.c:(.text+0x213af7): undefined reference to
> > > > > `fc_remove_host'
> > >    drivers/built-in.o: In function `storvsc_drv_init':
> > > > > storvsc_drv.c:(.init.text+0xcbcc): undefined reference to
> > > > > `fc_attach_transport'
> > > > > storvsc_drv.c:(.init.text+0xcc06): undefined reference to
> > > > > `fc_release_transport'
> > >    drivers/built-in.o: In function `storvsc_drv_exit':
> > > > > storvsc_drv.c:(.exit.text+0x123c): undefined reference to
> > > > > `fc_release_transport'
> > > 
> > > With this commit, the storvsc driver depends on FC atttributes.
> > > Make
> > > this
> > > dependency explicit.
> > > 
> > > Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
> > > Reported-by: Fengguang Wu <fengguang.wu@intel.com>
> > > ---
> > >  drivers/scsi/Kconfig |    1 +
> > >  1 files changed, 1 insertions(+), 0 deletions(-)
> > > 
> > > diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig
> > > index 64eed87..24365c3 100644
> > > --- a/drivers/scsi/Kconfig
> > > +++ b/drivers/scsi/Kconfig
> > > @@ -594,6 +594,7 @@ config XEN_SCSI_FRONTEND
> > >  config HYPERV_STORAGE
> > >  	tristate "Microsoft Hyper-V virtual storage driver"
> > >  	depends on SCSI && HYPERV
> > > +	depends on SCSI_FC_ATTRS
> > 
> > Well, I suppose continually sending the wrong patch until I get
> > annoyed
> > enough to send the right one is one way of doing it.  This patch is
> > wrong. what you want is below.
> 
> James, that was not my intent; although it is a tempting strategy!
> Here is an excerpt of your comments on v2 of this patch:
> (dated Jan 29 of this year):
> 
> "No ... if you want to depend on the FC_ATTRS then a simple depend
> works.  If you want to be able to build without them or with them,
> then
> that line must read
> 
> depends on m || SCSI_FC_ATTRS != m"
> 
> Since all I wanted was to depend on FC_ATTRS I chose to go with your
> recommendation -
> which also happened to be what I had initially sent (v1 of this
> patch).

If you're going to depend on the FC_ATTRS then you don't need all of
the 

#if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)

In the driver, because you're never building without it.  I thought
those were put in to satisfy Hannes' request that the driver be
buildable without the attributes?

> > You want HYPERV_STORAGE to be built in if the FC attributes are,
> > otherwise you don't care because if they're N the FC code will be
> > compiled out.
> 
> If FC attributes are built in, I have no issue - I want to be able to 
> build the storvsc driver both as a module as well as built in. 
> However, if storvsc is built as part of the kernel, I want to make 
> sure that FC attributes are also built as part of the kernel. The 
> build test failure that was reported was this case. With this patch, 
> the build issue reported by kbuild cannot happen since if the 
> FC_ATTRS are built as a module, storvsc cannot be builtin.

Oh, right, the line should read

depends on m || SCSI_FC_ATTRS != m

for that case.

James