diff options
| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2024-06-20 15:22:00 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2024-06-24 16:41:23 -0700 |
| commit | b22800f9d3b142bf2550dd47ff738b9feedc1093 (patch) | |
| tree | db9356395ad16645c87889b4bb2cd6a4509e3a88 /net/core | |
| parent | a8760d0d1497878d01f901ef2038c7389187a8af (diff) | |
dev: Use nested-BH locking for softnet_data.process_queue.
softnet_data::process_queue 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.
softnet_data::input_queue_head can be updated lockless. This is fine
because this value is only update CPU local by the local backlog_napi
thread.
Add a local_lock_t to softnet_data and use local_lock_nested_bh() for locking
of process_queue. This change adds only lockdep coverage and does not
alter the functional behaviour for !PREEMPT_RT.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-11-bigeasy@linutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/dev.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 73c4d14e4feb..8ef727c2ae2b 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -449,7 +449,9 @@ static RAW_NOTIFIER_HEAD(netdev_chain); * queue in the local softnet handler. */ -DEFINE_PER_CPU_ALIGNED(struct softnet_data, softnet_data); +DEFINE_PER_CPU_ALIGNED(struct softnet_data, softnet_data) = { + .process_queue_bh_lock = INIT_LOCAL_LOCK(process_queue_bh_lock), +}; EXPORT_PER_CPU_SYMBOL(softnet_data); /* Page_pool has a lockless array/stack to alloc/recycle pages. @@ -5949,6 +5951,7 @@ static void flush_backlog(struct work_struct *work) } backlog_unlock_irq_enable(sd); + local_lock_nested_bh(&softnet_data.process_queue_bh_lock); skb_queue_walk_safe(&sd->process_queue, skb, tmp) { if (skb->dev->reg_state == NETREG_UNREGISTERING) { __skb_unlink(skb, &sd->process_queue); @@ -5956,6 +5959,7 @@ static void flush_backlog(struct work_struct *work) rps_input_queue_head_incr(sd); } } + local_unlock_nested_bh(&softnet_data.process_queue_bh_lock); local_bh_enable(); } @@ -6077,7 +6081,9 @@ static int process_backlog(struct napi_struct *napi, int quota) while (again) { struct sk_buff *skb; + local_lock_nested_bh(&softnet_data.process_queue_bh_lock); while ((skb = __skb_dequeue(&sd->process_queue))) { + local_unlock_nested_bh(&softnet_data.process_queue_bh_lock); rcu_read_lock(); __netif_receive_skb(skb); rcu_read_unlock(); @@ -6086,7 +6092,9 @@ static int process_backlog(struct napi_struct *napi, int quota) return work; } + local_lock_nested_bh(&softnet_data.process_queue_bh_lock); } + local_unlock_nested_bh(&softnet_data.process_queue_bh_lock); backlog_lock_irq_disable(sd); if (skb_queue_empty(&sd->input_pkt_queue)) { @@ -6101,8 +6109,10 @@ static int process_backlog(struct napi_struct *napi, int quota) napi->state &= NAPIF_STATE_THREADED; again = false; } else { + local_lock_nested_bh(&softnet_data.process_queue_bh_lock); skb_queue_splice_tail_init(&sd->input_pkt_queue, &sd->process_queue); + local_unlock_nested_bh(&softnet_data.process_queue_bh_lock); } backlog_unlock_irq_enable(sd); } |