IB/uverbs: Rework the locking for cleaning up the ucontext

The locking here has always been a bit crazy and spread out, upon some
careful analysis we can simplify things.

Create a single function uverbs_destroy_ufile_hw() that internally handles
all locking. This pulls together pieces of this process that were
sprinkled all over the places into one place, and covers them with one
lock.

This eliminates several duplicate/confusing locks and makes the control
flow in ib_uverbs_close() and ib_uverbs_free_hw_resources() extremely
simple.

Unfortunately we have to keep an extra mutex, ucontext_lock.  This lock is
logically part of the rwsem and provides the 'down write, fail if write
locked, wait if read locked' semantic we require.

Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

1 files changed, 2 insertions, 4 deletions

diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
index 58b16e840e56..ca9b0450d3f9 100644
--- a/drivers/infiniband/core/uverbs.h
+++ b/drivers/infiniband/core/uverbs.h
@@ -136,9 +136,9 @@ struct ib_uverbs_completion_event_file {
 
 struct ib_uverbs_file {
 	struct kref				ref;
-	struct mutex				mutex;
-	struct mutex                            cleanup_mutex; /* protect cleanup */
 	struct ib_uverbs_device		       *device;
+	/* Protects writing to ucontext */
+	struct mutex				ucontext_lock;
 	struct ib_ucontext		       *ucontext;
 	struct ib_event_handler			event_handler;
 	struct ib_uverbs_async_event_file       *async_file;
@@ -155,8 +155,6 @@ struct ib_uverbs_file {
 	spinlock_t		uobjects_lock;
 	struct list_head	uobjects;
 
-	enum rdma_remove_reason cleanup_reason;
-
 	struct idr		idr;
 	/* spinlock protects write access to idr */
 	spinlock_t		idr_lock;