linux/arch/mips
Cesar Eduardo Barros 597781f3e5 kmap_atomic: make kunmap_atomic() harder to misuse
kunmap_atomic() is currently at level -4 on Rusty's "Hard To Misuse"
list[1] ("Follow common convention and you'll get it wrong"), except in
some architectures when CONFIG_DEBUG_HIGHMEM is set[2][3].

kunmap() takes a pointer to a struct page; kunmap_atomic(), however, takes
takes a pointer to within the page itself.  This seems to once in a while
trip people up (the convention they are following is the one from
kunmap()).

Make it much harder to misuse, by moving it to level 9 on Rusty's list[4]
("The compiler/linker won't let you get it wrong").  This is done by
refusing to build if the type of its first argument is a pointer to a
struct page.

The real kunmap_atomic() is renamed to kunmap_atomic_notypecheck()
(which is what you would call in case for some strange reason calling it
with a pointer to a struct page is not incorrect in your code).

The previous version of this patch was compile tested on x86-64.

[1] http://ozlabs.org/~rusty/index.cgi/tech/2008-04-01.html
[2] In these cases, it is at level 5, "Do it right or it will always
    break at runtime."
[3] At least mips and powerpc look very similar, and sparc also seems to
    share a common ancestor with both; there seems to be quite some
    degree of copy-and-paste coding here. The include/asm/highmem.h file
    for these three archs mention x86 CPUs at its top.
[4] http://ozlabs.org/~rusty/index.cgi/tech/2008-03-30.html
[5] As an aside, could someone tell me why mn10300 uses unsigned long as
    the first parameter of kunmap_atomic() instead of void *?

Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Cc: Russell King <linux@arm.linux.org.uk> (arch/arm)
Cc: Ralf Baechle <ralf@linux-mips.org> (arch/mips)
Cc: David Howells <dhowells@redhat.com> (arch/frv, arch/mn10300)
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com> (arch/mn10300)
Cc: Kyle McMartin <kyle@mcmartin.ca> (arch/parisc)
Cc: Helge Deller <deller@gmx.de> (arch/parisc)
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> (arch/parisc)
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> (arch/powerpc)
Cc: Paul Mackerras <paulus@samba.org> (arch/powerpc)
Cc: "David S. Miller" <davem@davemloft.net> (arch/sparc)
Cc: Thomas Gleixner <tglx@linutronix.de> (arch/x86)
Cc: Ingo Molnar <mingo@redhat.com> (arch/x86)
Cc: "H. Peter Anvin" <hpa@zytor.com> (arch/x86)
Cc: Arnd Bergmann <arnd@arndb.de> (include/asm-generic)
Cc: Rusty Russell <rusty@rustcorp.com.au> ("Hard To Misuse" list)
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-08-09 20:44:54 -07:00
..
alchemy MIPS: Ritually kill stupid printk. 2010-08-05 13:26:27 +01:00
ar7 MIPS: AR7: rewrite of cpmac_get_mac() 2010-08-05 13:26:02 +01:00
bcm47xx MIPS: BCM47xx: Fix nvram_getenv return value. 2010-08-05 13:26:31 +01:00
bcm63xx MIPS: BCM63xx: Migrate to new platform makefile style. 2010-08-05 13:25:54 +01:00
boot MIPS: strip the un-needed sections of vmlinuz 2010-08-05 13:26:34 +01:00
cavium-octeon MIPS: Octeon: Allow more than 3.75GB of memory with PCIe 2010-08-05 13:26:31 +01:00
cobalt
configs MIPS: Alchemy: Add basic support for the GPR board 2010-08-05 13:26:09 +01:00
dec
emma MIPS: Ritually kill stupid printk. 2010-08-05 13:26:27 +01:00
fw
include/asm kmap_atomic: make kunmap_atomic() harder to misuse 2010-08-09 20:44:54 -07:00
jazz
jz4740 MIPS: JZ4740: Add qi_lb60 board support 2010-08-05 13:26:20 +01:00
kernel Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb 2010-08-05 15:59:48 -07:00
lasat MIPS: Lasat: Migrate to new platform makefile style. 2010-08-05 13:25:53 +01:00
lib
loongson MIPS: Loongson: Remove unused macro LOONGSON_PERFCNT_IRQ 2010-08-05 13:26:26 +01:00
math-emu
mipssim
mm kmap_atomic: make kunmap_atomic() harder to misuse 2010-08-09 20:44:54 -07:00
mti-malta
nxp/pnx8550/common MIPS: PNX8550: Move code one directory level up. 2010-08-05 13:25:56 +01:00
oprofile
pci MIPS: Octeon: Allow more than 3.75GB of memory with PCIe 2010-08-05 13:26:31 +01:00
pmc-sierra MIPS: PNX Removing dead CONFIG_PMCTWILED 2010-08-05 13:26:00 +01:00
pnx833x MIPS: PNX833x: Migrate to new platform makefile style. 2010-08-05 13:25:56 +01:00
pnx8550 MIPS: PNX8550: Migrate to new platform makefile style. 2010-08-05 13:25:57 +01:00
power
powertv MIPS: PowerTV: Separate PowerTV USB support from non-USB code 2010-08-05 13:26:34 +01:00
rb532
sgi-ip22
sgi-ip27
sgi-ip32
sibyte MIPS: Sibyte: Migrate to new platform makefile style. 2010-08-05 13:25:55 +01:00
sni
txx9 MIPS: TXx9: Migrate to new platform makefile style. 2010-08-05 13:25:55 +01:00
vr41xx
wrppmc MIPS: WRPPMC: Migrate to new platform makefile style. 2010-08-05 13:25:51 +01:00
Kbuild
Kbuild.platforms MIPS: JZ4740: Add Kbuild files 2010-08-05 13:26:17 +01:00
Kconfig Merge branch 'timers-timekeeping-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-08-06 13:18:29 -07:00
Kconfig.debug
Makefile Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6 2010-08-05 14:10:07 -07:00