path: root/net/core/netpoll.c
diff options
authorDebabrata Banerjee <dbanerje@akamai.com>2018-10-18 11:18:26 -0400
committerDavid S. Miller <davem@davemloft.net>2018-10-19 17:01:43 -0700
commitc9fbd71f73094311b31ee703a918e9e0df502cef (patch)
tree1f3d85463e83f066e5aa7e335d70382f0fc23dba /net/core/netpoll.c
parentMerge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net (diff)
netpoll: allow cleanup to be synchronous
This fixes a problem introduced by: commit 2cde6acd49da ("netpoll: Fix __netpoll_rcu_free so that it can hold the rtnl lock") When using netconsole on a bond, __netpoll_cleanup can asynchronously recurse multiple times, each __netpoll_free_async call can result in more __netpoll_free_async's. This means there is now a race between cleanup_work queues on multiple netpoll_info's on multiple devices and the configuration of a new netpoll. For example if a netconsole is set to enable 0, reconfigured, and enable 1 immediately, this netconsole will likely not work. Given the reason for __netpoll_free_async is it can be called when rtnl is not locked, if it is locked, we should be able to execute synchronously. It appears to be locked everywhere it's called from. Generalize the design pattern from the teaming driver for current callers of __netpoll_free_async. CC: Neil Horman <nhorman@tuxdriver.com> CC: "David S. Miller" <davem@davemloft.net> Signed-off-by: Debabrata Banerjee <dbanerje@akamai.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/netpoll.c')
1 files changed, 5 insertions, 16 deletions
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 3ae899805f8b..5da9552b186b 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -57,7 +57,6 @@ DEFINE_STATIC_SRCU(netpoll_srcu);
static void zap_completion_queue(void);
-static void netpoll_async_cleanup(struct work_struct *work);
static unsigned int carrier_timeout = 4;
module_param(carrier_timeout, uint, 0644);
@@ -589,7 +588,6 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev)
np->dev = ndev;
strlcpy(np->dev_name, ndev->name, IFNAMSIZ);
- INIT_WORK(&np->cleanup_work, netpoll_async_cleanup);
if (ndev->priv_flags & IFF_DISABLE_NETPOLL) {
np_err(np, "%s doesn't support polling, aborting\n",
@@ -788,10 +786,6 @@ void __netpoll_cleanup(struct netpoll *np)
struct netpoll_info *npinfo;
- /* rtnl_dereference would be preferable here but
- * rcu_cleanup_netpoll path can put us in here safely without
- * holding the rtnl, so plain rcu_dereference it is
- */
npinfo = rtnl_dereference(np->dev->npinfo);
if (!npinfo)
@@ -812,21 +806,16 @@ void __netpoll_cleanup(struct netpoll *np)
-static void netpoll_async_cleanup(struct work_struct *work)
+void __netpoll_free(struct netpoll *np)
- struct netpoll *np = container_of(work, struct netpoll, cleanup_work);
- rtnl_lock();
+ /* Wait for transmitting packets to finish before freeing. */
+ synchronize_rcu_bh();
- rtnl_unlock();
-void __netpoll_free_async(struct netpoll *np)
- schedule_work(&np->cleanup_work);
void netpoll_cleanup(struct netpoll *np)