[PATCH] might_sleep() checks for x86 usercopy functions

[PATCH] might_sleep() checks for x86 usercopy functions

From: Matt Mackall <mpm@selenic.com>

This only checks in the non-__ versions, as those are occassionally
called inside things like kmap_atomic pairs which take a spinlock in
with highmem. It's all conditional on CONFIG_DEBUG_SPINLOCK_SLEEP
(which isn't quite the right name) so there's no overhead for normal
builds.