ww-mutex: clarify help text for DEBUG_WW_MUTEX_SLOWPATH

We really don't want distro's enabling this in their kernels.  Try and
make that more clear.

Signed-off-by: Rob Clark <robdclark@gmail.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 07c28323f88fe99d08900d82e3eacec6ca88fb91..1b233fc6746616beb56ff6d1be6ade998db4af24 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -892,6 +892,10 @@ config DEBUG_WW_MUTEX_SLOWPATH
         the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
         will test all possible w/w mutex interface abuse with the
         exception of simply not acquiring all the required locks.
+        Note that this feature can introduce significant overhead, so
+        it really should not be enabled in a production or distro kernel,
+        even a debug kernel.  If you are a driver writer, enable it.  If
+        you are a distro, do not.
 
 config DEBUG_LOCK_ALLOC
        bool "Lock debugging: detect incorrect freeing of live locks"