On Tue, Feb 20, 2018 at 01:58:26PM +0100, Christian KÃnig wrote:
amdgpu needs to verify if userspace sends us valid addresses and the simplestMuch thanks for Cc'ing the relevant maintainers :/
way of doing this is to check if the buffer object is locked with the ticket
of the current submission.
Clean up the access to the ww_mutex internals by providing a function
for this and extend the check to the thread owning the underlying mutex.
Signed-off-by: Christian KÃnig <christian.koenig@xxxxxxx>
---Much better than the previous version. If you want to bike-shed, you can
include/linux/ww_mutex.h | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/include/linux/ww_mutex.h b/include/linux/ww_mutex.h
index 39fda195bf78..14e4149d3d9d 100644
--- a/include/linux/ww_mutex.h
+++ b/include/linux/ww_mutex.h
@@ -358,4 +358,21 @@ static inline bool ww_mutex_is_locked(struct ww_mutex *lock)
return mutex_is_locked(&lock->base);
}
+/**
+ * ww_mutex_is_owned_by - is the w/w mutex locked by this task in that context
+ * @lock: the mutex to be queried
+ * @ctx: the w/w acquire context to test
+ *
+ * If @ctx is not NULL test if the mutex is owned by this context.
+ * If @ctx is NULL test if the mutex is owned by the current thread.
+ */
+static inline bool ww_mutex_is_owned_by(struct ww_mutex *lock,
+ struct ww_acquire_ctx *ctx)
+{
+ if (ctx)
+ return likely(READ_ONCE(lock->ctx) == ctx);
+ else
+ return likely(__mutex_owner(&lock->base) == current);
+}
leave out the 'else' and unindent the last line.
I do worry about potential users of .ctx = NULL, though. It makes it far
too easy to do recursive locking, which is something we should strongly
discourage.