nft_pcpu_tun_ctx is a per-CPU variable and relies on disabled BH for its locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT this data structure requires explicit locking. Make a struct with a nft_inner_tun_ctx member (original nft_pcpu_tun_ctx) and a local_lock_t and use local_lock_nested_bh() for locking. This change adds only lockdep coverage and does not alter the functional behaviour for !PREEMPT_RT. Cc: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> Cc: Jozsef Kadlecsik <kadlec@xxxxxxxxxxxxx> Cc: netfilter-devel@xxxxxxxxxxxxxxx Cc: coreteam@xxxxxxxxxxxxx Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> --- net/netfilter/nft_inner.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/net/netfilter/nft_inner.c b/net/netfilter/nft_inner.c index 817ab978d24a1..c4569d4b92285 100644 --- a/net/netfilter/nft_inner.c +++ b/net/netfilter/nft_inner.c @@ -23,7 +23,14 @@ #include <linux/ip.h> #include <linux/ipv6.h> -static DEFINE_PER_CPU(struct nft_inner_tun_ctx, nft_pcpu_tun_ctx); +struct nft_inner_tun_ctx_locked { + struct nft_inner_tun_ctx ctx; + local_lock_t bh_lock; +}; + +static DEFINE_PER_CPU(struct nft_inner_tun_ctx_locked, nft_pcpu_tun_ctx) = { + .bh_lock = INIT_LOCAL_LOCK(bh_lock), +}; /* Same layout as nft_expr but it embeds the private expression data area. */ struct __nft_expr { @@ -237,12 +244,15 @@ static bool nft_inner_restore_tun_ctx(const struct nft_pktinfo *pkt, struct nft_inner_tun_ctx *this_cpu_tun_ctx; local_bh_disable(); - this_cpu_tun_ctx = this_cpu_ptr(&nft_pcpu_tun_ctx); + local_lock_nested_bh(&nft_pcpu_tun_ctx.bh_lock); + this_cpu_tun_ctx = this_cpu_ptr(&nft_pcpu_tun_ctx.ctx); if (this_cpu_tun_ctx->cookie != (unsigned long)pkt->skb) { local_bh_enable(); + local_unlock_nested_bh(&nft_pcpu_tun_ctx.bh_lock); return false; } *tun_ctx = *this_cpu_tun_ctx; + local_unlock_nested_bh(&nft_pcpu_tun_ctx.bh_lock); local_bh_enable(); return true; @@ -254,9 +264,11 @@ static void nft_inner_save_tun_ctx(const struct nft_pktinfo *pkt, struct nft_inner_tun_ctx *this_cpu_tun_ctx; local_bh_disable(); - this_cpu_tun_ctx = this_cpu_ptr(&nft_pcpu_tun_ctx); + local_lock_nested_bh(&nft_pcpu_tun_ctx.bh_lock); + this_cpu_tun_ctx = this_cpu_ptr(&nft_pcpu_tun_ctx.ctx); if (this_cpu_tun_ctx->cookie != tun_ctx->cookie) *this_cpu_tun_ctx = *tun_ctx; + local_unlock_nested_bh(&nft_pcpu_tun_ctx.bh_lock); local_bh_enable(); } -- 2.47.2