netdev - [RFC PATCH] bonding: use mutex lock in bond_get

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Date:   Fri, 15 Feb 2019 21:50:56 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     <netdev@...r.kernel.org>, Willem de Bruijn <willemb@...gle.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jay Vosburgh <j.vosburgh@...il.com>,
        Veaceslav Falico <vfalico@...il.com>,
        Eric Dumazet <edumazet@...gle.com>
CC:     <weiyongjun1@...wei.com>, Kefeng Wang <wangkefeng.wang@...wei.com>
Subject: [RFC PATCH] bonding: use mutex lock in bond_get_stats()

With CONFIG_DEBUG_SPINLOCK=y, we find following stack,

 BUG: spinlock wrong CPU on CPU#0, ip/16047
  lock: 0xffff803f5febc998, .magic: dead4ead, .owner: ip/16047, .owner_cpu: 0
 CPU: 1 PID: 16047 Comm: ip Kdump: loaded Tainted: G            E 4.19.12.aarch64 #1
 Hardware name: Huawei TaiShan 2280 V2/BC82AMDA, BIOS TA BIOS TaiShan 2280 V2 - B900 01/29/2019
 Call trace:
  dump_backtrace+0x0/0x1c0
  show_stack+0x24/0x30
  dump_stack+0x90/0xbc
  spin_dump+0x84/0xa8
  do_raw_spin_unlock+0xf8/0x100
  _raw_spin_unlock+0x20/0x30
  bond_get_stats+0x110/0x140 [bonding]
  rtnl_fill_stats+0x50/0x150
  rtnl_fill_ifinfo+0x4d4/0xd18
  rtnl_dump_ifinfo+0x200/0x3a8
  netlink_dump+0x100/0x2b0
  netlink_recvmsg+0x310/0x3e8
  sock_recvmsg+0x58/0x68
  ___sys_recvmsg+0xd0/0x278
  __sys_recvmsg+0x74/0xd0
  __arm64_sys_recvmsg+0x2c/0x38
  el0_svc_common+0x7c/0x118
  el0_svc_handler+0x30/0x40
  el0_svc+0x8/0xc

and then lead to softlockup issue, fix this by using mutex lock instead
of spin lock.

Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
---

Not sure if this is right fix, please correct me if I'm wrong.

 drivers/net/bonding/bond_main.c | 6 +++---
 include/net/bonding.h           | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 485462d3087f..3f7849525759 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3452,7 +3452,7 @@ static void bond_get_stats(struct net_device *bond_dev,
 	struct list_head *iter;
 	struct slave *slave;
 
-	spin_lock_nested(&bond->stats_lock, bond_get_nest_level(bond_dev));
+	mutex_lock_nested(&bond->stats_lock, bond_get_nest_level(bond_dev));
 	memcpy(stats, &bond->bond_stats, sizeof(*stats));
 
 	rcu_read_lock();
@@ -3468,7 +3468,7 @@ static void bond_get_stats(struct net_device *bond_dev,
 	rcu_read_unlock();
 
 	memcpy(&bond->bond_stats, stats, sizeof(*stats));
-	spin_unlock(&bond->stats_lock);
+	mutex_unlock(&bond->stats_lock);
 }
 
 static int bond_do_ioctl(struct net_device *bond_dev, struct ifreq *ifr, int cmd)
@@ -4284,7 +4284,7 @@ void bond_setup(struct net_device *bond_dev)
 	struct bonding *bond = netdev_priv(bond_dev);
 
 	spin_lock_init(&bond->mode_lock);
-	spin_lock_init(&bond->stats_lock);
+	mutex_init(&bond->stats_lock);
 	bond->params = bonding_defaults;
 
 	/* Initialize pointers */
diff --git a/include/net/bonding.h b/include/net/bonding.h
index b46d68acf701..3a6dbb2b376c 100644
--- a/include/net/bonding.h
+++ b/include/net/bonding.h
@@ -205,7 +205,7 @@ struct bonding {
 	 * ALB mode (6) - to sync the use and modifications of its hash table
 	 */
 	spinlock_t mode_lock;
-	spinlock_t stats_lock;
+	struct mutex	stats_lock;
 	u8	 send_peer_notif;
 	u8       igmp_retrans;
 #ifdef CONFIG_PROC_FS
-- 
2.20.1