diff mbox series

[v2,net-next,3/8] net: enqueue_to_backlog() change vs not running device

Message ID 20240329154225.349288-4-edumazet@google.com (mailing list archive)
State Accepted
Delegated to: Netdev Maintainers
Headers show
Series net: rps: misc changes | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next, async
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: 950 this patch: 950
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 4 of 4 maintainers
netdev/build_clang success Errors and warnings before: 955 this patch: 955
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: 961 this patch: 961
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 27 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-03-31--03-00 (tests: 953)

Commit Message

Eric Dumazet March 29, 2024, 3:42 p.m. UTC
If the device attached to the packet given to enqueue_to_backlog()
is not running, we drop the packet.

But we accidentally increase sd->dropped, giving false signals
to admins: sd->dropped should be reserved to cpu backlog pressure,
not to temporary glitches at device dismantles.

While we are at it, perform the netif_running() test before
we get the rps lock, and use REASON_DEV_READY
drop reason instead of NOT_SPECIFIED.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/core/dev.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/net/core/dev.c b/net/core/dev.c
index c136e80dea6182faac153f0cc4149bf8698b6676..4ad7836365e68f700b26dba2c50515a8c18329cf 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4801,12 +4801,13 @@  static int enqueue_to_backlog(struct sk_buff *skb, int cpu,
 	unsigned long flags;
 	unsigned int qlen;
 
-	reason = SKB_DROP_REASON_NOT_SPECIFIED;
+	reason = SKB_DROP_REASON_DEV_READY;
+	if (!netif_running(skb->dev))
+		goto bad_dev;
+
 	sd = &per_cpu(softnet_data, cpu);
 
 	backlog_lock_irq_save(sd, &flags);
-	if (!netif_running(skb->dev))
-		goto drop;
 	qlen = skb_queue_len(&sd->input_pkt_queue);
 	if (qlen <= READ_ONCE(net_hotdata.max_backlog) &&
 	    !skb_flow_limit(skb, qlen)) {
@@ -4827,10 +4828,10 @@  static int enqueue_to_backlog(struct sk_buff *skb, int cpu,
 	}
 	reason = SKB_DROP_REASON_CPU_BACKLOG;
 
-drop:
 	sd->dropped++;
 	backlog_unlock_irq_restore(sd, &flags);
 
+bad_dev:
 	dev_core_stats_rx_dropped_inc(skb->dev);
 	kfree_skb_reason(skb, reason);
 	return NET_RX_DROP;