* Michael S. Tsirkin <m...@redhat.com> wrote:
> The only reason uaccess routines might sleep
> is if they fault. Make this explicit for
> __copy_from_user_nocache, and consistent with
> copy_from_user and friends.
>
> Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
> ---
>
> I've updated all other arches as well - still
> build-testing. Any objections to the x86 patch?
>
> arch/x86/include/asm/uaccess_64.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/uaccess_64.h
> b/arch/x86/include/asm/uaccess_64.h
> index 142810c..4f7923d 100644
> --- a/arch/x86/include/asm/uaccess_64.h
> +++ b/arch/x86/include/asm/uaccess_64.h
> @@ -235,7 +235,7 @@ extern long __copy_user_nocache(void *dst, const void
> __user *src,
> static inline int
> __copy_from_user_nocache(void *dst, const void __user *src, unsigned size)
> {
> - might_sleep();
> + might_fault();
> return __copy_user_nocache(dst, src, size, 1);
Looks good to me:
Acked-by: Ingo Molnar <mi...@kernel.org>
... but while reviewing the effects I noticed a bug in might_fault():
#ifdef CONFIG_PROVE_LOCKING
void might_fault(void)
{
/*
* Some code (nfs/sunrpc) uses socket ops on kernel memory while
* holding the mmap_sem, this is safe because kernel memory doesn't
* get paged out, therefore we'll never actually fault, and the
* below annotations will generate false positives.
*/
if (segment_eq(get_fs(), KERNEL_DS))
return;
might_sleep();
the might_sleep() call should come first. With the current code
might_fault() schedules differently depending on CONFIG_PROVE_LOCKING,
which is an undesired semantical side effect ...
So please fix that too while at it.
Thanks,
Ingo
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