diff mbox series

[net-next] net: flush_backlog() small changes

Message ID 20250204144825.316785-1-edumazet@google.com (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series [net-next] net: flush_backlog() small changes | expand

Checks

Context Check Description
netdev/series_format success Single patches do not need cover letters
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 5 of 5 maintainers
netdev/build_clang success Errors and warnings before: 2 this patch: 2
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 5 this patch: 5
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 38 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 79 this patch: 79
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2025-02-05--00-00 (tests: 886)

Commit Message

Eric Dumazet Feb. 4, 2025, 2:48 p.m. UTC 
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>
---
 net/core/dev.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/net/core/dev.c b/net/core/dev.c
index c0021cbd28fc11e4c4eb6184d98a2505fa674871..cd31e78a7d8a2229e3dc17d08bb638f862148823 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6119,16 +6119,18 @@  EXPORT_SYMBOL(netif_receive_skb_list);
 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);
 		}
 	}
@@ -6136,14 +6138,16 @@  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)