linux/arch/x86/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
..
kmemcheck kmemcheck: Test the full object in kmemcheck_is_obj_initialized() 2010-02-17 21:39:08 +02:00
dump_pagetables.c x86, mm: Create symbolic index into address_markers array 2010-07-20 16:56:19 -07:00
extable.c x86, 64-bit: Move K8 B step iret fixup to fault entry asm 2009-10-12 18:29:46 +02:00
fault.c Merge branch 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-12-05 15:33:27 -08:00
gup.c x86, doc: Fix minor spelling error in arch/x86/mm/gup.c 2010-02-02 16:00:44 -08:00
highmem_32.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
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 update email address 2010-07-19 10:56:54 +02:00
init.c Merge branch 'master' into export-slabh 2010-04-05 11:37:28 +09:00
iomap_32.c x86, pat: Add PAT reserve free to io_mapping* APIs 2009-08-26 15:41:16 -07:00
ioremap.c x86, iomap: Fix wrong page aligned size calculation in ioremapping code 2010-07-20 16:56:35 -07:00
k8topology_64.c x86: Move find_smp_config() earlier and avoid bootmem usage 2009-11-24 12:10:51 +01:00
kmmio.c x86, kmmio/mmiotrace: Fix double free of kmmio_fault_pages 2010-06-18 11:30:09 +02:00
Makefile x86, pat: Migrate to rbtree only backend for pat memtype management 2010-02-18 15:41:36 -08:00
memtest.c x86: memtest: use pointers of equal type for comparison 2009-06-11 16:26:35 +02:00
mmap.c x86: Use helpers for rlimits 2010-01-27 15:17:31 -08:00
mmio-mod.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
numa_32.c x86: Make 32bit support NO_BOOTMEM 2010-02-12 09:42:39 -08:00
numa_64.c numa: x86_64: use generic percpu var numa_node_id() implementation 2010-05-27 09:12:57 -07:00
numa.c x86/mm: Remove unused DBG() macro 2010-05-31 10:01:53 +02:00
pageattr-test.c x86: make sure the CPA test code's use of _PAGE_UNUSED1 is obvious 2008-09-05 17:09:57 +02:00
pageattr.c Merge branch 'drm-ttm-pool' into drm-core-next 2010-04-20 13:12:28 +10:00
pat_internal.h x86, pat: Fix memory leak in free_memtype 2010-05-26 11:26:04 -07:00
pat_rbtree.c rbtree: Undo augmented trees performance damage and regression 2010-07-05 14:43:50 +02:00
pat.c Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-08-06 10:17:52 -07:00
pf_in.c x86,mmiotrace: Add support for tracing STOS instruction 2010-08-02 01:32:01 +02:00
pf_in.h x86 mmiotrace: move files into arch/x86/mm/. 2008-05-24 11:25:37 +02:00
pgtable_32.c x86: remove last traces of quicklist usage 2010-05-24 13:33:31 -07:00
pgtable.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
physaddr.c x86: split __phys_addr out into separate file 2009-09-10 11:48:55 -07:00
physaddr.h x86: split __phys_addr out into separate file 2009-09-10 11:48:55 -07:00
setup_nx.c x86, mm: Report state of NX protections during boot 2009-11-16 13:44:59 -08:00
srat_32.c x86: Fix checking of SRAT when node 0 ram is not from 0 2009-12-16 16:43:37 -08:00
srat_64.c Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-05-18 09:17:50 -07:00
testmmiotrace.c x86, kmmio/mmiotrace: Fix double free of kmmio_fault_pages 2010-06-18 11:30:09 +02:00
tlb.c x86, tlb: Clean up and correct used type 2010-07-21 21:48:15 +02:00