On Sun, 2013-05-26 at 17:31 +0300, Michael S. Tsirkin wrote:
> The only reason uaccess routines might sleep
> is if they fault. Make this explicit.
>
> Arnd Bergmann suggested that the following code
> if (!is_kernel_addr((unsigned long)__pu_addr))
> might_fault();
> can be further simplified by adding a version of might_fault
> that includes the kernel addr check.
>
> Will be considered as a further optimization in future.
>
> Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
As long as Peter is happy with the general semantics of might_fault()
and you have at least build-tested it, then I'm happy.
Acked-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
> ---
> arch/powerpc/include/asm/uaccess.h | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/uaccess.h
> b/arch/powerpc/include/asm/uaccess.h
> index 4db4959..9485b43 100644
> --- a/arch/powerpc/include/asm/uaccess.h
> +++ b/arch/powerpc/include/asm/uaccess.h
> @@ -178,7 +178,7 @@ do {
> \
> long __pu_err; \
> __typeof__(*(ptr)) __user *__pu_addr = (ptr); \
> if (!is_kernel_addr((unsigned long)__pu_addr)) \
> - might_sleep(); \
> + might_fault(); \
> __chk_user_ptr(ptr); \
> __put_user_size((x), __pu_addr, (size), __pu_err); \
> __pu_err; \
> @@ -188,7 +188,7 @@ do {
> \
> ({ \
> long __pu_err = -EFAULT; \
> __typeof__(*(ptr)) __user *__pu_addr = (ptr); \
> - might_sleep(); \
> + might_fault(); \
> if (access_ok(VERIFY_WRITE, __pu_addr, size)) \
> __put_user_size((x), __pu_addr, (size), __pu_err); \
> __pu_err; \
> @@ -268,7 +268,7 @@ do {
> \
> const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \
> __chk_user_ptr(ptr); \
> if (!is_kernel_addr((unsigned long)__gu_addr)) \
> - might_sleep(); \
> + might_fault(); \
> __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
> (x) = (__typeof__(*(ptr)))__gu_val; \
> __gu_err; \
> @@ -282,7 +282,7 @@ do {
> \
> const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \
> __chk_user_ptr(ptr); \
> if (!is_kernel_addr((unsigned long)__gu_addr)) \
> - might_sleep(); \
> + might_fault(); \
> __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
> (x) = (__typeof__(*(ptr)))__gu_val; \
> __gu_err; \
> @@ -294,7 +294,7 @@ do {
> \
> long __gu_err = -EFAULT; \
> unsigned long __gu_val = 0; \
> const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \
> - might_sleep(); \
> + might_fault(); \
> if (access_ok(VERIFY_READ, __gu_addr, (size))) \
> __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
> (x) = (__typeof__(*(ptr)))__gu_val; \
> @@ -419,14 +419,14 @@ static inline unsigned long
> __copy_to_user_inatomic(void __user *to,
> static inline unsigned long __copy_from_user(void *to,
> const void __user *from, unsigned long size)
> {
> - might_sleep();
> + might_fault();
> return __copy_from_user_inatomic(to, from, size);
> }
>
> static inline unsigned long __copy_to_user(void __user *to,
> const void *from, unsigned long size)
> {
> - might_sleep();
> + might_fault();
> return __copy_to_user_inatomic(to, from, size);
> }
>
> @@ -434,7 +434,7 @@ extern unsigned long __clear_user(void __user *addr,
> unsigned long size);
>
> static inline unsigned long clear_user(void __user *addr, unsigned long size)
> {
> - might_sleep();
> + might_fault();
> if (likely(access_ok(VERIFY_WRITE, addr, size)))
> return __clear_user(addr, size);
> if ((unsigned long)addr < TASK_SIZE) {
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