Re: [RT PATCH 2/2] net: add a lock around icmp_sk()
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: 2016-09-01 08:11:53
Also in:
linux-rt-users, lkml
On 2016-08-31 09:37:43 [-0700], Eric Dumazet wrote:
quoted
--- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c@@ -216,12 +219,14 @@ static inline struct sock *icmp_xmit_lock(struct net *net) local_bh_disable(); + local_lock(icmp_sk_lock);Deadlock alert ? Please read the comment few lines after, explaining why we have to use spin_trylock(). Or maybe I should double check what is local_lock() in RT
On !RT local_lock() is preempt_disable().
On RT local_lock() is a per-CPU sleeping spinlock which can be taken
recursively by the owner.
On a "normal" ping reply we have
- icmp_reply()
- icmp_xmit_lock()
- local_lock()
- icmp_push_reply()
icmp_send()
- local_lock()
so that works. I didn't manage to resolve a possible dst_link_failure()
path but I would assume it is like the above (where the owner takes the
same local_lock() multiple times).
Sebastian