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597781f3e5
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>
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|---|---|---|
| .. | ||
| agp.h | ||
| asm-offsets.h | ||
| asmregs.h | ||
| assembly.h | ||
| atomic.h | ||
| auxvec.h | ||
| bitops.h | ||
| bitsperlong.h | ||
| bug.h | ||
| bugs.h | ||
| byteorder.h | ||
| cache.h | ||
| cacheflush.h | ||
| checksum.h | ||
| compat_rt_sigframe.h | ||
| compat_signal.h | ||
| compat_ucontext.h | ||
| compat.h | ||
| cputime.h | ||
| current.h | ||
| delay.h | ||
| device.h | ||
| div64.h | ||
| dma-mapping.h | ||
| dma.h | ||
| eisa_bus.h | ||
| eisa_eeprom.h | ||
| elf.h | ||
| emergency-restart.h | ||
| errno.h | ||
| fb.h | ||
| fcntl.h | ||
| fixmap.h | ||
| floppy.h | ||
| ftrace.h | ||
| futex.h | ||
| grfioctl.h | ||
| hardirq.h | ||
| hardware.h | ||
| hw_irq.h | ||
| ide.h | ||
| io.h | ||
| ioctl.h | ||
| ioctls.h | ||
| ipcbuf.h | ||
| irq_regs.h | ||
| irq.h | ||
| Kbuild | ||
| kdebug.h | ||
| kmap_types.h | ||
| led.h | ||
| linkage.h | ||
| local.h | ||
| local64.h | ||
| machdep.h | ||
| mc146818rtc.h | ||
| mckinley.h | ||
| mman.h | ||
| mmu_context.h | ||
| mmu.h | ||
| mmzone.h | ||
| module.h | ||
| msgbuf.h | ||
| mutex.h | ||
| page.h | ||
| param.h | ||
| parisc-device.h | ||
| parport.h | ||
| pci.h | ||
| pdc_chassis.h | ||
| pdc.h | ||
| pdcpat.h | ||
| percpu.h | ||
| perf_event.h | ||
| perf.h | ||
| pgalloc.h | ||
| pgtable.h | ||
| poll.h | ||
| posix_types.h | ||
| prefetch.h | ||
| processor.h | ||
| psw.h | ||
| ptrace.h | ||
| real.h | ||
| resource.h | ||
| ropes.h | ||
| rt_sigframe.h | ||
| rtc.h | ||
| runway.h | ||
| scatterlist.h | ||
| sections.h | ||
| segment.h | ||
| sembuf.h | ||
| serial.h | ||
| setup.h | ||
| shmbuf.h | ||
| shmparam.h | ||
| sigcontext.h | ||
| siginfo.h | ||
| signal.h | ||
| smp.h | ||
| socket.h | ||
| sockios.h | ||
| spinlock_types.h | ||
| spinlock.h | ||
| stat.h | ||
| statfs.h | ||
| string.h | ||
| superio.h | ||
| swab.h | ||
| syscall.h | ||
| system.h | ||
| termbits.h | ||
| termios.h | ||
| thread_info.h | ||
| timex.h | ||
| tlb.h | ||
| tlbflush.h | ||
| topology.h | ||
| traps.h | ||
| types.h | ||
| uaccess.h | ||
| ucontext.h | ||
| unaligned.h | ||
| unistd.h | ||
| unwind.h | ||
| user.h | ||
| vga.h | ||
| xor.h | ||