[PATCH v2 00/10] uaccess: better might_sleep/might_fault behavior

From: Michael S. Tsirkin
Date: Thu May 16 2013 - 07:11:41 EST

This improves the might_fault annotations used
by uaccess routines:

1. The only reason uaccess routines might sleep
is if they fault. Make this explicit for
all architectures.
2. Accesses (e.g through socket ops) to kernel memory
with KERNEL_DS like net/sunrpc does will never sleep.
Remove an unconditinal might_sleep in the inline
might_fault in kernel.h
(used when PROVE_LOCKING is not set).
3. Accesses with pagefault_disable return EFAULT
but won't cause caller to sleep.
Check for that and avoid might_sleep when

I'd like these changes to go in for the benefit of
the vhost driver where we want to call socket ops
under a spinlock, and fall back on slower thread handler
on error.

Please review, and consider for 3.11.

If the changes look good, what's the best way to merge them?
Maybe core/locking makes sense?

Note on arch code updates:
I tested x86_64 code.
Other architectures were build-tested.
I don't have cross-build environment for arm64, tile, microblaze and
mn10300 architectures. The changes look safe enough
but would appreciate review/acks from arch maintainers.

Version 1 of this change was titled
x86: uaccess s/might_sleep/might_fault/

Changes from v1:
add more architectures
fix might_fault() scheduling differently depending
on CONFIG_PROVE_LOCKING, as suggested by Ingo

Michael S. Tsirkin (10):
asm-generic: uaccess s/might_sleep/might_fault/
arm64: uaccess s/might_sleep/might_fault/
frv: uaccess s/might_sleep/might_fault/
m32r: uaccess s/might_sleep/might_fault/
microblaze: uaccess s/might_sleep/might_fault/
mn10300: uaccess s/might_sleep/might_fault/
powerpc: uaccess s/might_sleep/might_fault/
tile: uaccess s/might_sleep/might_fault/
x86: uaccess s/might_sleep/might_fault/
kernel: might_fault does not imply might_sleep

arch/arm64/include/asm/uaccess.h | 4 ++--
arch/frv/include/asm/uaccess.h | 4 ++--
arch/m32r/include/asm/uaccess.h | 12 ++++++------
arch/microblaze/include/asm/uaccess.h | 6 +++---
arch/mn10300/include/asm/uaccess.h | 4 ++--
arch/powerpc/include/asm/uaccess.h | 16 ++++++++--------
arch/tile/include/asm/uaccess.h | 2 +-
arch/x86/include/asm/uaccess_64.h | 2 +-
include/asm-generic/uaccess.h | 10 +++++-----
include/linux/kernel.h | 1 -
mm/memory.c | 14 +++++++++-----
11 files changed, 39 insertions(+), 36 deletions(-)


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