linux/arch/mips/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
..
c-octeon.c MIPS: Give Octeon+ CPUs their own cputype. 2010-02-27 12:53:26 +01:00
c-r3k.c MIPS: Build fix - include <linux/smp.h> into all smp_processor_id() users. 2009-06-24 18:34:39 +01:00
c-r4k.c MIPS: Build fix - include <linux/smp.h> into all smp_processor_id() users. 2009-06-24 18:34:39 +01:00
c-tx39.c MIPS: Build fix - include <linux/smp.h> into all smp_processor_id() users. 2009-06-24 18:34:39 +01:00
cache.c MIPS: Fix __vmalloc() etc. on MIPS for non-GPL modules 2010-04-12 17:26:21 +01:00
cerr-sb1.c MIPS: Sibyte: Use hweight8 instead of counting bits 2009-12-17 01:57:16 +00:00
cex-gen.S
cex-oct.S MIPS: Add Cavium OCTEON processor support files to arch/mips/cavium-octeon. 2009-01-11 09:57:21 +00:00
cex-sb1.S [MIPS] Fix loads of section missmatches 2008-03-12 14:14:41 +00:00
dma-default.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
extable.c MIPS: Eleminate filenames from comments 2009-08-03 17:52:40 +01:00
fault.c MIPS: kprobe: Add support. 2010-08-05 13:26:29 +01:00
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
init.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
ioremap.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
Makefile MIPS: Add -Werror to arch/mips/Kbuild 2010-08-05 13:25:44 +01:00
page.c MIPS: Move arch/mips/mm/uasm.h to arch/mips/include/asm/uasm.h 2010-02-27 12:53:19 +01:00
pgtable-32.c
pgtable-64.c MIPS: Two-level pagetables for 64-bit kernels with 64KB pages. 2010-02-27 12:53:03 +01:00
sc-ip22.c MIPS: IP22: Make indy_sc_ops variable static 2008-11-20 19:42:33 +00:00
sc-mips.c MIPS: MIPSxx SC: Avoid destructive invalidation on partial L2 cachelines. 2009-09-30 21:47:00 +02:00
sc-r5k.c [MIPS] Fix loads of section missmatches 2008-03-12 14:14:41 +00:00
sc-rm7k.c MIPS: RM7000: Add support for tertiary cache 2010-08-05 13:26:06 +01:00
tlb-r3k.c MIPS: Build fix - include <linux/smp.h> into all smp_processor_id() users. 2009-06-24 18:34:39 +01:00
tlb-r4k.c MIPS: Implement Read Inhibit/eXecute Inhibit 2010-02-27 12:53:26 +01:00
tlb-r8k.c MIPS: Build fix - include <linux/smp.h> into all smp_processor_id() users. 2009-06-24 18:34:39 +01:00
tlbex-fault.S
tlbex.c MIPS: JZ4740: Add base support for Ingenic JZ4740 System-on-a-Chip 2010-08-05 13:26:12 +01:00
uasm.c MIPS: uasm: Add option to export uasm API. 2010-08-05 13:26:21 +01:00