Re: [PATCH] video: ep93xx-fb: add missing include of linux/module.h

On 11-08-22 07:48 PM, Ryan Mallon wrote:

On 23/08/11 02:40, H Hartley Sweeten wrote:

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On Sunday, August 21, 2011 5:31 PM, Ryan Mallon wrote:

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On 22/08/11 10:06, Axel Lin wrote:

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2011/8/22 Ryan Mallon[off-list ref]:

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On 22/08/11 09:41, Ryan Mallon wrote:

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On 22/08/11 00:39, Axel Lin wrote:

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ep93xx-fb.c uses interfaces from linux/module.h,
so it should include that file.  This patch fixes below build errors.

What actually changed to make these files broken? Did some other header
previously include module.h for us? How many other drivers are broken?

Anyway, the change is okay.

Acked-by: Ryan Mallon<redacted>

Actually, having a second look at this it does not look right.

drivers/video/ep93xx-fb.c includes linux/platform.h (as its first include),
which includes linux/driver.h, which includes linux/module.h.

For the record, this is exactly what we are trying to fix -- relying on
implicit and non-obvious include chaining.  If you are writing a modular
driver, you should include module.h explicitly.

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Just tested on Linus' latest tree and both this driver and the ep93xx
backlight driver build fine. What kernel version are you using?

~Ryan

hi Ryan,

The patch is against linux-next tree.
I got build error for ep93xx-fb.c and ep93xx_bl.c on linux-next tree.
( next-20110819 )

Ok, I see now. The change which caused the breakage is fdb697c:
"include: replace linux/module.h with "struct module" wherever
possible". How many other drivers got broken now that device.h does not
include module.h?

Probably a lot...  Which is one of the reasons linux-next exists.. . ;-)

Does anybody know how we can quickly determine which drivers are broken 
short of doing an allyesconfig? I tried to do some quick tricks by 
passing files which contain THIS_MODULE/MODULE_* through cpp, but I get 
loads of errors in headers files because I'm missing some config 
includes. Is there an easy way to get the kbuild arguments for the 
current .config so I can pass them to cpp?

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Actually, Paul Gortmaker caused this breakage with the commit.  He should
take a deeper look and see what it broke.  From his commit:

     Most of the implicit dependencies on module.h being present by
     these headers pulling it in have been now weeded out, so we can
     finally make this change with hopefully minimal breakage.

Quick glance:

ryanm@kiwi:linux-2.6$ grep -lR "^MODULE_" drivers/  | xargs grep -L 
"linux/module.h\|linux/moduleloader.h\|linux/miscdevice.h\|linux/regmap.h\|linux/irq.h"  
| wc -l
579

This can be misleading because subsystems may have a common header that
includes module.h, and then all the C files include that common header.
I think the e1000 network driver is one example.

ryanm@kiwi:linux-2.6$ grep -lR "THIS_MODULE" drivers/ | xargs grep -L 
"linux/module.h\|linux/moduleloader.h\|linux/miscdevice.h\|linux/regmap.h\|linux/irq.h\|linux/export.h\|acpi/platform/aclinux.h\|xen/xenbus.h"   
| wc -l
399

Not sure how many of those are really broken though since there may be a 
few other ways to include module.h/export.h. I would also think there 
would be a lot more build failure reports if all of those were broken :-).

Exactly.  I've done allyesconfig, allnoconfig, allmodconfig builds for all
the common arch and even half a dozen or so uncommon arch.  Plus in the case
of things like arm and powerpc with board specific config files that are in
arch/*/configs, I've built all those.  So a couple of odd cases like this
which don't get build coverage through any of the above was expected, and
hence the value of being in linux-next for a while.

Thanks all for the report, I'll make sure these files get the proper
include header they need.

Paul.

~Ryan