linux/arch/sparc/mm
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
..
btfixup.c sparc: remove CONFIG_SUN4 2008-08-31 20:59:37 -07:00
extable.c module: trim exception table on init free. 2009-06-12 21:47:04 +09:30
fault_32.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next-2.6 2010-03-02 07:56:44 -08:00
fault_64.c sparc: Support show_unhandled_signals. 2010-03-01 00:02:23 -08:00
generic_32.c sparc: move EXPORT_SYMBOL to the symbols definition 2009-01-08 16:58:05 -08:00
generic_64.c sparc64: move EXPORT_SYMBOL to the symbols definition 2009-01-08 16:58:20 -08:00
highmem.c kmap_atomic: make kunmap_atomic() harder to misuse 2010-08-09 20:44:54 -07:00
hugetlbpage.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
hypersparc.S sparc: remove CVS keywords 2008-05-20 00:33:44 -07:00
init_32.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
init_64.c lmb: rename to memblock 2010-07-14 17:14:00 +10:00
init_64.h sparc64: Fix definition of VMEMMAP_SIZE. 2009-11-23 16:38:56 -08:00
io-unit.c sparc: remove references to of_device and to_of_device 2010-07-24 09:58:22 -06:00
iommu.c Merge branch 'next-devicetree' of git://git.secretlab.ca/git/linux-2.6 2010-08-05 15:57:35 -07:00
leon_mm.c sparc,leon: CONFIG_SPARC_LEON option and leon specific files. 2009-08-17 18:32:09 -07:00
loadmmu.c sparc,leon: Introduce the sparc-leon CPU type. 2009-08-17 18:32:10 -07:00
Makefile sparc,leon: Introduce the sparc-leon CPU type. 2009-08-17 18:32:10 -07:00
nosun4c.c MM: Pass a PTE pointer to update_mmu_cache() rather than the PTE itself 2010-02-20 16:41:46 +00:00
srmmu.c sparc32: Kill none_mask, it's bogus. 2010-05-25 23:36:31 -07:00
sun4c.c sparc32: Kill none_mask, it's bogus. 2010-05-25 23:36:31 -07:00
swift.S sparc: remove CVS keywords 2008-05-20 00:33:44 -07:00
tlb.c sparc,sparc64: unify mm/ 2008-12-04 09:16:59 -08:00
tsb.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
tsunami.S sparc/mm/: possible cleanups 2008-07-17 21:38:01 -07:00
ultra.S sparc64: Reschedule KGDB capture to a software interrupt. 2009-03-18 23:51:57 -07:00
viking.S sparc: remove CVS keywords 2008-05-20 00:33:44 -07:00