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net: flush_backlog() small changes

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[ Upstream commit cbe08724c18078564abefbf6591078a7c98e5e0f ]

Add READ_ONCE() around reads of skb->dev->reg_state, because
this field can be changed from other threads/cpus.

Instead of calling dev_kfree_skb_irq() and kfree_skb()
while interrupts are masked and locks held,
use a temporary list and use __skb_queue_purge_reason()

Use SKB_DROP_REASON_DEV_READY drop reason to better
describe why these skbs are dropped.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Link: https://patch.msgid.link/20250204144825.316785-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Eric Dumazet
2025-02-04 14:48:25 +00:00
committed by Greg Kroah-Hartman
parent ba59747562
commit 76e56dbe50
1 changed files with 8 additions and 4 deletions
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12
net/core/dev.c
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@@ -6034,16 +6034,18 @@ static DEFINE_PER_CPU(struct work_struct, flush_works);
static void flush_backlog(struct work_struct *work)
{
struct sk_buff *skb, *tmp;
struct sk_buff_head list;
struct softnet_data *sd;
__skb_queue_head_init(&list);
local_bh_disable();
sd = this_cpu_ptr(&softnet_data);
backlog_lock_irq_disable(sd);
skb_queue_walk_safe(&sd->input_pkt_queue, skb, tmp) {
if (skb->dev->reg_state == NETREG_UNREGISTERING) {
if (READ_ONCE(skb->dev->reg_state) == NETREG_UNREGISTERING) {
__skb_unlink(skb, &sd->input_pkt_queue);
dev_kfree_skb_irq(skb);
__skb_queue_tail(&list, skb);
rps_input_queue_head_incr(sd);
}
}
@@ -6051,14 +6053,16 @@ static void flush_backlog(struct work_struct *work)
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) {
if (READ_ONCE(skb->dev->reg_state) == NETREG_UNREGISTERING) {
__skb_unlink(skb, &sd->process_queue);
kfree_skb(skb);
__skb_queue_tail(&list, skb);
rps_input_queue_head_incr(sd);
}
}
local_unlock_nested_bh(&softnet_data.process_queue_bh_lock);
local_bh_enable();
__skb_queue_purge_reason(&list, SKB_DROP_REASON_DEV_READY);
}
static bool flush_required(int cpu)