linux-kernel - Re: [PATCH v2 3/3] asm-generic/io.h: Fix !CONFIG_GENERIC_IOMAP pci

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Message-ID: <BYAPR18MB2679E96E4FFF66F7520DD90DC53F0@BYAPR18MB2679.namprd18.prod.outlook.com>
Date:   Fri, 18 Sep 2020 11:06:40 +0000
From:   George Cherian <gcherian@...vell.com>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Catalin Marinas <catalin.marinas@....com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Arnd Bergmann" <arnd@...db.de>, Will Deacon <will@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Yang Yingliang <yangyingliang@...wei.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH v2 3/3] asm-generic/io.h: Fix !CONFIG_GENERIC_IOMAP
 pci_iounmap() implementation



> -----Original Message-----
> From: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Sent: Thursday, September 17, 2020 3:00 PM
> To: Catalin Marinas <catalin.marinas@....com>
> Cc: linux-kernel@...r.kernel.org; George Cherian <gcherian@...vell.com>;
> Arnd Bergmann <arnd@...db.de>; Will Deacon <will@...nel.org>; Bjorn
> Helgaas <bhelgaas@...gle.com>; Yang Yingliang
> <yangyingliang@...wei.com>; linux-pci@...r.kernel.org; linux-
> arch@...r.kernel.org; linux-arm-kernel@...ts.infradead.org; David S. Miller
> <davem@...emloft.net>
> Subject: Re: [PATCH v2 3/3] asm-generic/io.h: Fix
> !CONFIG_GENERIC_IOMAP pci_iounmap() implementation
> 
> 
> ----------------------------------------------------------------------
> On Wed, Sep 16, 2020 at 03:51:11PM +0100, Catalin Marinas wrote:
> > On Wed, Sep 16, 2020 at 12:06:58PM +0100, Lorenzo Pieralisi wrote:
> > > For arches that do not select CONFIG_GENERIC_IOMAP, the current
> > > pci_iounmap() function does nothing causing obvious memory leaks for
> > > mapped regions that are backed by MMIO physical space.
> > >
> > > In order to detect if a mapped pointer is IO vs MMIO, a check must
> > > made available to the pci_iounmap() function so that it can actually
> > > detect whether the pointer has to be unmapped.
> > >
> > > In configurations where CONFIG_HAS_IOPORT_MAP &&
> > > !CONFIG_GENERIC_IOMAP, a mapped port is detected using an
> > > ioport_map() stub defined in asm-generic/io.h.
> > >
> > > Use the same logic to implement a stub (ie __pci_ioport_unmap())
> > > that detects if the passed in pointer in pci_iounmap() is IO vs MMIO
> > > to iounmap conditionally and call it in pci_iounmap() fixing the issue.
> > >
> > > Leave __pci_ioport_unmap() as a NOP for all other config options.
> > >
> > > Reported-by: George Cherian <george.cherian@...vell.com>
> > > Link:
> > > https://urldefense.proofpoint.com/v2/url?u=https-3A__lore.kernel.org
> > > _lkml_20200905024811.74701-2D1-2Dyangyingliang-
> 40huawei.com&d=DwIBAg
> > >
> &c=nKjWec2b6R0mOyPaz7xtfQ&r=TjMsEFPc7dirkF6u2D3eSIS0cA8FeYpzRkk
> Mzr4a
> > > Cbk&m=UO5qU5LtNtCn6_gnT0rCkBxIm-w8jCaxHO6v7oK-U-
> I&s=CSGHQpKoVdNiqb1e
> > > DFuRUhka_Xv5o2PosWZ1rR8oOD4&e=
> > > Link:
> > > https://urldefense.proofpoint.com/v2/url?u=https-3A__lore.kernel.org
> > > _lkml_20200824132046.3114383-2D1-2Dgeorge.cherian-
> 40marvell.com&d=Dw
> > >
> IBAg&c=nKjWec2b6R0mOyPaz7xtfQ&r=TjMsEFPc7dirkF6u2D3eSIS0cA8FeYpz
> RkkM
> > > zr4aCbk&m=UO5qU5LtNtCn6_gnT0rCkBxIm-w8jCaxHO6v7oK-U-
> I&s=3B83oan7i1g3
> > > KaPgQmFK6PudR9GzvAPk33Z5Yyv-CMI&e=
> > > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> > > Cc: Arnd Bergmann <arnd@...db.de>
> > > Cc: George Cherian <george.cherian@...vell.com>
> > > Cc: Will Deacon <will@...nel.org>
> > > Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> > > Cc: Catalin Marinas <catalin.marinas@....com>
> > > Cc: Yang Yingliang <yangyingliang@...wei.com>
> > > ---
> > >  include/asm-generic/io.h | 39
> > > +++++++++++++++++++++++++++------------
> > >  1 file changed, 27 insertions(+), 12 deletions(-)
> >
> > This works for me. The only question I have is whether pci_iomap.h is
> > better than io.h for __pci_ioport_unmap(). These headers are really
> > confusing.
> 
> Yes they are, in total honesty there is much more to do to make them sane,
> this patch is just a band-aid.
> 
> I thought about moving this stuff into pci_iomap.h, though that file is
> included _independently_ from io.h from some arches so I tried to keep
> everything in io.h to minimize disruption.
> 
> We can merge this patch - since it is a fix after all - and then I can try to
> improve the whole pci_iounmap() includes.
> 
> > Either way:
> >
> > Reviewed-by: Catalin Marinas <catalin.marinas@....com>
> 
> Thanks a lot. I'd appreciate a tested-by from the George as he is the one who
> reported the problem.

Verified this patch and it works as expected.
Tested-by: George Cherian <george.cherian@...vell.com>
 
> Lorenzo