From: Maor Gottlieb <maorg@nvidia.com>
Date: Wed, 1 Sep 2021 08:48:13 +0000 (+0300)
Subject: net/mlx5: Fix potential sleeping in atomic context
X-Git-Tag: v4.19.207~30
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=e68a11a4324dbf7e98eeda55c16501263ce2d00c;p=users%2Fdwmw2%2Flinux.git

net/mlx5: Fix potential sleeping in atomic context

commit ee27e330a953595903979ffdb84926843595a9fe upstream.

Fixes the below flow of sleeping in atomic context by releasing
the RCU lock before calling to free_match_list.

build_match_list() <- disables preempt
-> free_match_list()
   -> tree_put_node()
      -> down_write_ref_node() <- take write lock

Fixes: 693c6883bbc4 ("net/mlx5: Add hash table for flow groups in flow table")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
index 774f0a619a6da..f0aa7f0e54803 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
@@ -1558,9 +1558,9 @@ static int build_match_list(struct match_list_head *match_head,
 
 		curr_match = kmalloc(sizeof(*curr_match), GFP_ATOMIC);
 		if (!curr_match) {
+			rcu_read_unlock();
 			free_match_list(match_head);
-			err = -ENOMEM;
-			goto out;
+			return -ENOMEM;
 		}
 		if (!tree_get_node(&g->node)) {
 			kfree(curr_match);
@@ -1569,7 +1569,6 @@ static int build_match_list(struct match_list_head *match_head,
 		curr_match->g = g;
 		list_add_tail(&curr_match->list, &match_head->list);
 	}
-out:
 	rcu_read_unlock();
 	return err;
 }