From: Jonathan Lemon <jonathan.lemon@gmail.com>
Date: Tue, 3 Dec 2019 14:01:14 -0800
Subject: xdp: obtain the mem_id mutex before trying to remove an entry.
Patch-mainline: v5.5-rc1
Git-commit: 86c76c09898332143be365c702cf8d586ed4ed21
References: bsc#1154353 bnc#1151927 5.3.18
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 <grygorii.strashko@ti.com>
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Tested-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
net/core/xdp.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -80,12 +80,8 @@ static void mem_xa_remove(struct xdp_mem
{
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(voi
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(voi
} while (xa == ERR_PTR(-EAGAIN));
rhashtable_walk_exit(&iter);
+
+ mutex_unlock(&mem_id_lock);
}
static void mem_id_disconnect(int id)