[PATCH net v2 2/2] netdevsim: psp: use atomic64 for psp stats counters
From: Daniel Zahka <daniel.zahka@gmail.com>
Date: 2026-05-29 13:15:33
Also in:
lkml
Subsystem:
netdevsim, networking drivers, the rest · Maintainers:
Jakub Kicinski, Andrew Lunn, "David S. Miller", Eric Dumazet, Paolo Abeni, Linus Torvalds
The existing u64_stats_t-based psp counters had two preexisting api
usage bugs: u64_stats_init() was never called on the syncp object, and
the writer side of the u64_stats_update_begin()/end() api was not
serialized. Switch the counters to atomic64_t instead. Atomics need
no initialization and are inherently safe against concurrent writers,
eliminating both bugs at once.
Use atomic64_t rather than atomic_long_t so byte counters don't wrap
at 4 GiB on 32-bit builds.
Fixes: 178f0763c5f3 ("netdevsim: implement psp device stats")
Assisted-by: Codex:gpt-5.5
Signed-off-by: Daniel Zahka <daniel.zahka@gmail.com>
---
drivers/net/netdevsim/netdevsim.h | 10 ++++------
drivers/net/netdevsim/psp.c | 24 ++++++++----------------
2 files changed, 12 insertions(+), 22 deletions(-)
diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
index d909c4160ea1..4c9cc96dcec3 100644
--- a/drivers/net/netdevsim/netdevsim.h
+++ b/drivers/net/netdevsim/netdevsim.h@@ -22,7 +22,6 @@ #include <linux/list.h> #include <linux/netdevice.h> #include <linux/ptp_mock.h> -#include <linux/u64_stats_sync.h> #include <net/devlink.h> #include <net/udp_tunnel.h> #include <net/xdp.h>
@@ -115,11 +114,10 @@ struct netdevsim { int rq_reset_mode; struct { - u64_stats_t rx_packets; - u64_stats_t rx_bytes; - u64_stats_t tx_packets; - u64_stats_t tx_bytes; - struct u64_stats_sync syncp; + atomic64_t rx_packets; + atomic64_t rx_bytes; + atomic64_t tx_packets; + atomic64_t tx_bytes; struct psp_dev __rcu *dev; struct dentry *rereg; struct mutex rereg_lock;
diff --git a/drivers/net/netdevsim/psp.c b/drivers/net/netdevsim/psp.c
index afe58b21041a..1c415b3d6f1a 100644
--- a/drivers/net/netdevsim/psp.c
+++ b/drivers/net/netdevsim/psp.c@@ -50,10 +50,8 @@ nsim_do_psp(struct sk_buff *skb, struct netdevsim *ns, } psp_len = skb->len - skb_inner_transport_offset(skb); - u64_stats_update_begin(&ns->psp.syncp); - u64_stats_inc(&ns->psp.tx_packets); - u64_stats_add(&ns->psp.tx_bytes, psp_len); - u64_stats_update_end(&ns->psp.syncp); + atomic64_inc(&ns->psp.tx_packets); + atomic64_add(psp_len, &ns->psp.tx_bytes); /* Now pretend we just received this frame */ peer_psd = rcu_dereference(peer_ns->psp.dev);
@@ -79,10 +77,8 @@ nsim_do_psp(struct sk_buff *skb, struct netdevsim *ns, refcount_inc(&(*psp_ext)->refcnt); skb->decrypted = 1; - u64_stats_update_begin(&peer_ns->psp.syncp); - u64_stats_inc(&peer_ns->psp.rx_packets); - u64_stats_add(&peer_ns->psp.rx_bytes, psp_len); - u64_stats_update_end(&peer_ns->psp.syncp); + atomic64_inc(&peer_ns->psp.rx_packets); + atomic64_add(psp_len, &peer_ns->psp.rx_bytes); } else { struct ipv6hdr *ip6h __maybe_unused; struct iphdr *iph;
@@ -180,20 +176,16 @@ static void nsim_assoc_del(struct psp_dev *psd, struct psp_assoc *pas) static void nsim_get_stats(struct psp_dev *psd, struct psp_dev_stats *stats) { struct netdevsim *ns = psd->drv_priv; - unsigned int start; /* WARNING: do *not* blindly zero stats in real drivers! * All required stats must be reported by the device! */ memset(stats, 0, sizeof(struct psp_dev_stats)); - do { - start = u64_stats_fetch_begin(&ns->psp.syncp); - stats->rx_bytes = u64_stats_read(&ns->psp.rx_bytes); - stats->rx_packets = u64_stats_read(&ns->psp.rx_packets); - stats->tx_bytes = u64_stats_read(&ns->psp.tx_bytes); - stats->tx_packets = u64_stats_read(&ns->psp.tx_packets); - } while (u64_stats_fetch_retry(&ns->psp.syncp, start)); + stats->rx_bytes = atomic64_read(&ns->psp.rx_bytes); + stats->rx_packets = atomic64_read(&ns->psp.rx_packets); + stats->tx_bytes = atomic64_read(&ns->psp.tx_bytes); + stats->tx_packets = atomic64_read(&ns->psp.tx_packets); } static struct psp_dev_ops nsim_psp_ops = {
--
2.52.0