linux-kernel - Re: [PATCH 1/5] ARM: add EXPORT_SYMBOL of hook_fault

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Message-ID: <2567476.SknW0BEsQJ@wuerfel>
Date:	Mon, 08 Feb 2016 10:53:10 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Paul Gortmaker <paul.gortmaker@...driver.com>
Cc:	linux-kernel@...r.kernel.org,
	Russell King <linux@....linux.org.uk>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Ley Foon Tan <lftan@...era.com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/5] ARM: add EXPORT_SYMBOL of hook_fault_code for PCI host modularization

On Sunday 07 February 2016 19:00:40 Paul Gortmaker wrote:
> In a discussion of a previous patch set[1], it was suggested that
> modularizing some of the PCI host support would be good to keep
> multi platform bzImage sizes smaller.
> 
> Two of the files that are candidates for conversion to tristate
> from bool are:
> 
> drivers/pci/host/pci-imx6.c
> drivers/pci/host/pci-keystone.c
> 
> However, doing the conversion reveals that they are going to fail
> at modpost time since hook_fault_code isn't currently exported.
> 
> Since we are now going to export it we also need to remove the
> __init tag, as the fcn needs to be present at insmod time.
> 
> [1] https://lkml.kernel.org/r/20160108203102.GH5354@localhost
> 

If we want to make hook_fault_code() visible, we at least also need
an unhook_fault_code() function that removes the fault handler
when unloading the module, and preferably does so in a safe way.

The usage of hook_fault_code() at least in the imx driver is also
problematic, as it just ignores all "imprecise external abort"
faults, whether they come from PCI or not.

	Arnd