From 86c76c09898332143be365c702cf8d586ed4ed21 Mon Sep 17 00:00:00 2001 From: Jonathan Lemon Date: Tue, 3 Dec 2019 14:01:14 -0800 Subject: xdp: obtain the mem_id mutex before trying to remove an entry. A lockdep splat was observed when trying to remove an xdp memory model from the table since the mutex was obtained when trying to remove the entry, but not before the table walk started: Fix the splat by obtaining the lock before starting the table walk. Fixes: c3f812cea0d7 ("page_pool: do not release pool until inflight == 0.") Reported-by: Grygorii Strashko Signed-off-by: Jonathan Lemon Tested-by: Grygorii Strashko Acked-by: Jesper Dangaard Brouer Acked-by: Ilias Apalodimas Signed-off-by: David S. Miller --- net/core/xdp.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/net/core/xdp.c b/net/core/xdp.c index e334fad0a6b8..7c8390ad4dc6 100644 --- a/net/core/xdp.c +++ b/net/core/xdp.c @@ -80,12 +80,8 @@ static void mem_xa_remove(struct xdp_mem_allocator *xa) { trace_mem_disconnect(xa); - mutex_lock(&mem_id_lock); - if (!rhashtable_remove_fast(mem_id_ht, &xa->node, mem_id_rht_params)) call_rcu(&xa->rcu, __xdp_mem_allocator_rcu_free); - - mutex_unlock(&mem_id_lock); } static void mem_allocator_disconnect(void *allocator) @@ -93,6 +89,8 @@ static void mem_allocator_disconnect(void *allocator) struct xdp_mem_allocator *xa; struct rhashtable_iter iter; + mutex_lock(&mem_id_lock); + rhashtable_walk_enter(mem_id_ht, &iter); do { rhashtable_walk_start(&iter); @@ -106,6 +104,8 @@ static void mem_allocator_disconnect(void *allocator) } while (xa == ERR_PTR(-EAGAIN)); rhashtable_walk_exit(&iter); + + mutex_unlock(&mem_id_lock); } static void mem_id_disconnect(int id) -- cgit