[v3] PCI: Add pci_iounmap

In case if any architecture selects CONFIG_GENERIC_PCI_IOMAP and not
CONFIG_GENERIC_IOMAP, then the pci_iounmap function is reduced to a NULL
function. Due to this the managed release variants or even the explicit
pci_iounmap calls doesn't really remove the mappings.

This issue is seen on an arm64 based system. arm64 by default selects
only CONFIG_GENERIC_PCI_IOMAP and not CONFIG_GENERIC_IOMAP from this
'commit cb61f6769b88 ("ARM64: use GENERIC_PCI_IOMAP")'

Also '66eab4df288a ("lib: add GENERIC_PCI_IOMAP")' moved only  the iomap
functions to lib/pci_iomap.c. The pci_iounmap() was left in lib/iomap.c
as different achitectures has its own pci_iounmap implementation.
For architectures, which doesn't have pci_iounmap implemented, this
would lead to a potential leak. So provide a generic iounmap function in
lib/pci_iomap.c.

Simple bind/unbind test of any pci driver using pcim_iomap/pci_iomap,
would lead to the following error message after long hour tests

"allocation failed: out of vmalloc space - use vmalloc=<size> to
increase size."

Signed-off-by: George Cherian <george.cherian@marvell.com>
---
* Changes from v2
	- Get rid of the #ifdefs around pci_iounmap()
* Changes from v1
	- Fix the 0-day compilation error.
	- Mark the lib/iomap pci_iounmap call as weak incase
	if any architecture have there own implementation.
 include/asm-generic/io.h        | 4 ++++
 include/asm-generic/iomap.h     | 1 -
 include/asm-generic/pci_iomap.h | 1 +
 lib/pci_iomap.c                 | 6 ++++++
 4 files changed, 11 insertions(+), 1 deletion(-)

Hi George,

I love your patch! Yet something to improve:

[auto build test ERROR on pci/next]
[also build test ERROR on linux/master linus/master asm-generic/master v5.9-rc2 next-20200824]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/George-Cherian/PCI-Add-pci_iounmap/20200824-212149
base:   https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git next
config: powerpc-allyesconfig (attached as .config)
compiler: powerpc64-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=powerpc 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   powerpc64-linux-ld: lib/pci_iomap.o: in function `__crc_pci_iounmap':
>> (.rodata+0x10): multiple definition of `__crc_pci_iounmap'; lib/iomap.o:(.rodata+0x68): first defined here

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

On 2020/8/25 9:25, kernel test robot wrote:
> Hi George,
>
> I love your patch! Yet something to improve:
>
> [auto build test ERROR on pci/next]
> [also build test ERROR on linux/master linus/master asm-generic/master v5.9-rc2 next-20200824]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch]
>
> url:    https://github.com/0day-ci/linux/commits/George-Cherian/PCI-Add-pci_iounmap/20200824-212149
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git next
> config: powerpc-allyesconfig (attached as .config)
> compiler: powerpc64-linux-gcc (GCC) 9.3.0
> reproduce (this is a W=1 build):
>          wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>          chmod +x ~/bin/make.cross
>          # save the attached .config to linux build tree
>          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=powerpc
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
>
> All errors (new ones prefixed by >>):
>
>     powerpc64-linux-ld: lib/pci_iomap.o: in function `__crc_pci_iounmap':
>>> (.rodata+0x10): multiple definition of `__crc_pci_iounmap'; lib/iomap.o:(.rodata+0x68): first defined here
EXPORT_SYMBOL(pci_iounmap) in lib/iomap.c need be removed.
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org