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authorMike Marciniszyn <mike.marciniszyn@intel.com>2015-11-02 12:13:25 -0500
committerDoug Ledford <dledford@redhat.com>2015-12-07 16:39:26 -0500
commitd144da8c6f51f48ec39d891ea9dff80169c45f3b (patch)
treeb2cc120f870989c2cb4cdd328d0cf7f8355eb012 /include
parent57ab2512138205fe7836332fb4742441e53907ff (diff)
downloadlinux-d144da8c6f51f48ec39d891ea9dff80169c45f3b.tar.gz
IB/core: use RCU for uverbs id lookup
The current implementation gets a spin_lock, and at any scale with
qib and hfi1 post send, the lock contention grows exponentially
with the number of QPs.

idr_find() is RCU compatibile, so read doesn't need the lock.

Change to use rcu_read_lock() and rcu_read_unlock() in
__idr_get_uobj().

kfree_rcu() is used to insure a grace period between the
idr removal and actual free.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Reviewed-By: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Diffstat (limited to 'include')
-rw-r--r--include/rdma/ib_verbs.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 9a68a19532ba..120da1d7f57e 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -1271,6 +1271,7 @@ struct ib_uobject {
 	int			id;		/* index into kernel idr */
 	struct kref		ref;
 	struct rw_semaphore	mutex;		/* protects .live */
+	struct rcu_head		rcu;		/* kfree_rcu() overhead */
 	int			live;
 };