From 72cdc67e7fa74931b055df3a76852bab551f1a04 Mon Sep 17 00:00:00 2001 From: Qingfang Deng Date: Thu, 28 Aug 2025 09:20:16 +0800 Subject: pppoe: remove rwlock usage Like ppp_generic.c, convert the PPPoE socket hash table to use RCU for lookups and a spinlock for updates. This removes rwlock usage and allows lockless readers on the fast path. - Mark hash table and list pointers as __rcu. - Use spin_lock() to protect writers. - Readers use rcu_dereference() under rcu_read_lock(). All known callers of get_item() already hold the RCU read lock, so no additional locking is needed. - get_item() now uses refcount_inc_not_zero() instead of sock_hold() to safely take a reference. This prevents crashes if a socket is already in the process of being freed (sk_refcnt == 0). - Set SOCK_RCU_FREE to defer socket freeing until after an RCU grace period. - Move skb_queue_purge() into sk_destruct callback to ensure purge happens after an RCU grace period. Signed-off-by: Qingfang Deng Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250828012018.15922-1-dqfext@gmail.com Signed-off-by: Jakub Kicinski --- include/linux/if_pppox.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/if_pppox.h b/include/linux/if_pppox.h index ff3beda1312c..db45d6f1c4f4 100644 --- a/include/linux/if_pppox.h +++ b/include/linux/if_pppox.h @@ -43,7 +43,7 @@ struct pppox_sock { /* struct sock must be the first member of pppox_sock */ struct sock sk; struct ppp_channel chan; - struct pppox_sock *next; /* for hash table */ + struct pppox_sock __rcu *next; /* for hash table */ union { struct pppoe_opt pppoe; struct pptp_opt pptp; -- cgit v1.2.3