kernel: better document the use_mm/unuse_mm API contract

Switch the function documentation to kerneldoc comments, and add
WARN_ON_ONCE asserts that the calling thread is a kernel thread and does
not have ->mm set (or has ->mm set in the case of unuse_mm).

Also give the functions a kthread_ prefix to better document the use case.

[[email protected]: fix a comment typo, cover the newly merged use_mm/unuse_mm caller in vfio]
  Link: http://lkml.kernel.org/r/[email protected]
[[email protected]: powerpc/vas: fix up for {un}use_mm() rename]
  Link: http://lkml.kernel.org/r/[email protected]

Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Stephen Rothwell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Tested-by: Jens Axboe <[email protected]>
Reviewed-by: Jens Axboe <[email protected]>
Acked-by: Felix Kuehling <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]> [usb]
Acked-by: Haren Myneni <[email protected]>
Cc: Alex Deucher <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Felipe Balbi <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Zhenyu Wang <[email protected]>
Cc: Zhi Wang <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index c2d40c9672d6..12258ea077cf 100644
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -200,8 +200,8 @@ bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *work);
 
 void kthread_destroy_worker(struct kthread_worker *worker);
 
-void use_mm(struct mm_struct *mm);
-void unuse_mm(struct mm_struct *mm);
+void kthread_use_mm(struct mm_struct *mm);
+void kthread_unuse_mm(struct mm_struct *mm);
 
 struct cgroup_subsys_state;