sunrpc: add a rcu_head to svc_rqst and use kfree_rcu to free it

...also make the manipulation of sp_all_threads list use RCU-friendly
functions.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Tested-by: Chris Worley <chris.worley@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index a06a891012e5..b90d1bca4349 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -616,7 +616,7 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node)
         serv->sv_nrthreads++;
         spin_lock_bh(&pool->sp_lock);
         pool->sp_nrthreads++;
-        list_add(&rqstp->rq_all, &pool->sp_all_threads);
+        list_add_rcu(&rqstp->rq_all, &pool->sp_all_threads);
         spin_unlock_bh(&pool->sp_lock);
         rqstp->rq_server = serv;
         rqstp->rq_pool = pool;
@@ -684,7 +684,8 @@ found_pool:
                  * so we don't try to kill it again.
                  */
                 rqstp = list_entry(pool->sp_all_threads.next, struct svc_rqst, rq_all);
-                list_del_init(&rqstp->rq_all);
+                set_bit(RQ_VICTIM, &rqstp->rq_flags);
+                list_del_rcu(&rqstp->rq_all);
                 task = rqstp->rq_task;
         }
         spin_unlock_bh(&pool->sp_lock);
@@ -782,10 +783,11 @@ svc_exit_thread(struct svc_rqst *rqstp)
 
         spin_lock_bh(&pool->sp_lock);
         pool->sp_nrthreads--;
-        list_del(&rqstp->rq_all);
+        if (!test_and_set_bit(RQ_VICTIM, &rqstp->rq_flags))
+                list_del_rcu(&rqstp->rq_all);
         spin_unlock_bh(&pool->sp_lock);
 
-        kfree(rqstp);
+        kfree_rcu(rqstp, rq_rcu_head);
 
         /* Release the server */
         if (serv)