* Re: [PATCH net-next] net: spacemit: Make stats_lock softirq-safe
2025-09-19 12:04 ` [PATCH net-next] net: spacemit: Make stats_lock softirq-safe Vivian Wang
@ 2025-09-19 12:25 ` Marek Szyprowski
2025-09-22 19:00 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: Marek Szyprowski @ 2025-09-19 12:25 UTC (permalink / raw)
To: Vivian Wang, Andrew Lunn, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni, Yixun Lan, Maxime Chevallier,
Troy Mitchell, Vadim Fedorenko
Cc: netdev, linux-riscv, spacemit, linux-kernel, Vivian Wang
On 19.09.2025 14:04, Vivian Wang wrote:
> While most of the statistics functions (emac_get_stats64() and such) are
> called with softirqs enabled, emac_stats_timer() is, as its name
> suggests, also called from a timer, i.e. called in softirq context.
>
> All of these take stats_lock. Therefore, make stats_lock softirq-safe by
> changing spin_lock() into spin_lock_bh() for the functions that get
> statistics.
>
> Also, instead of directly calling emac_stats_timer() in emac_up() and
> emac_resume(), set the timer to trigger instead, so that
> emac_stats_timer() is only called from the timer. It will keep using
> spin_lock().
>
> This fixes a lockdep warning, and potential deadlock when stats_timer is
> triggered in the middle of getting statistics.
>
> Fixes: bfec6d7f2001 ("net: spacemit: Add K1 Ethernet MAC")
> Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Closes: https://lore.kernel.org/all/a52c0cf5-0444-41aa-b061-a0a1d72b02fe@samsung.com/
> Signed-off-by: Vivian Wang <wangruikang@iscas.ac.cn>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
> Thanks a lot for catching this, Marek!
> ---
> drivers/net/ethernet/spacemit/k1_emac.c | 30 +++++++++++++++---------------
> 1 file changed, 15 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/net/ethernet/spacemit/k1_emac.c b/drivers/net/ethernet/spacemit/k1_emac.c
> index 928fea02198c3754f63a7b33fc25c5dd8c2b59f9..e1c5faff3b71c7d4ceba2ea194d9c888f0e71b70 100644
> --- a/drivers/net/ethernet/spacemit/k1_emac.c
> +++ b/drivers/net/ethernet/spacemit/k1_emac.c
> @@ -135,7 +135,7 @@ struct emac_priv {
> bool flow_control_autoneg;
> u8 flow_control;
>
> - /* Hold while touching hardware statistics */
> + /* Softirq-safe, hold while touching hardware statistics */
> spinlock_t stats_lock;
> };
>
> @@ -1239,7 +1239,7 @@ static void emac_get_stats64(struct net_device *dev,
> /* This is the only software counter */
> storage->tx_dropped = emac_get_stat_tx_drops(priv);
>
> - spin_lock(&priv->stats_lock);
> + spin_lock_bh(&priv->stats_lock);
>
> emac_stats_update(priv);
>
> @@ -1261,7 +1261,7 @@ static void emac_get_stats64(struct net_device *dev,
> storage->rx_missed_errors = rx_stats->stats.rx_drp_fifo_full_pkts;
> storage->rx_missed_errors += rx_stats->stats.rx_truncate_fifo_full_pkts;
>
> - spin_unlock(&priv->stats_lock);
> + spin_unlock_bh(&priv->stats_lock);
> }
>
> static void emac_get_rmon_stats(struct net_device *dev,
> @@ -1275,7 +1275,7 @@ static void emac_get_rmon_stats(struct net_device *dev,
>
> *ranges = emac_rmon_hist_ranges;
>
> - spin_lock(&priv->stats_lock);
> + spin_lock_bh(&priv->stats_lock);
>
> emac_stats_update(priv);
>
> @@ -1294,7 +1294,7 @@ static void emac_get_rmon_stats(struct net_device *dev,
> rmon_stats->hist[5] = rx_stats->stats.rx_1024_1518_pkts;
> rmon_stats->hist[6] = rx_stats->stats.rx_1519_plus_pkts;
>
> - spin_unlock(&priv->stats_lock);
> + spin_unlock_bh(&priv->stats_lock);
> }
>
> static void emac_get_eth_mac_stats(struct net_device *dev,
> @@ -1307,7 +1307,7 @@ static void emac_get_eth_mac_stats(struct net_device *dev,
> tx_stats = &priv->tx_stats;
> rx_stats = &priv->rx_stats;
>
> - spin_lock(&priv->stats_lock);
> + spin_lock_bh(&priv->stats_lock);
>
> emac_stats_update(priv);
>
> @@ -1325,7 +1325,7 @@ static void emac_get_eth_mac_stats(struct net_device *dev,
> mac_stats->FramesAbortedDueToXSColls =
> tx_stats->stats.tx_excessclsn_pkts;
>
> - spin_unlock(&priv->stats_lock);
> + spin_unlock_bh(&priv->stats_lock);
> }
>
> static void emac_get_pause_stats(struct net_device *dev,
> @@ -1338,14 +1338,14 @@ static void emac_get_pause_stats(struct net_device *dev,
> tx_stats = &priv->tx_stats;
> rx_stats = &priv->rx_stats;
>
> - spin_lock(&priv->stats_lock);
> + spin_lock_bh(&priv->stats_lock);
>
> emac_stats_update(priv);
>
> pause_stats->tx_pause_frames = tx_stats->stats.tx_pause_pkts;
> pause_stats->rx_pause_frames = rx_stats->stats.rx_pause_pkts;
>
> - spin_unlock(&priv->stats_lock);
> + spin_unlock_bh(&priv->stats_lock);
> }
>
> /* Other statistics that are not derivable from standard statistics */
> @@ -1393,14 +1393,14 @@ static void emac_get_ethtool_stats(struct net_device *dev,
> u64 *rx_stats = (u64 *)&priv->rx_stats;
> int i;
>
> - spin_lock(&priv->stats_lock);
> + spin_lock_bh(&priv->stats_lock);
>
> emac_stats_update(priv);
>
> for (i = 0; i < ARRAY_SIZE(emac_ethtool_rx_stats); i++)
> data[i] = rx_stats[emac_ethtool_rx_stats[i].offset];
>
> - spin_unlock(&priv->stats_lock);
> + spin_unlock_bh(&priv->stats_lock);
> }
>
> static int emac_ethtool_get_regs_len(struct net_device *dev)
> @@ -1769,7 +1769,7 @@ static int emac_up(struct emac_priv *priv)
>
> netif_start_queue(ndev);
>
> - emac_stats_timer(&priv->stats_timer);
> + mod_timer(&priv->stats_timer, jiffies);
>
> return 0;
>
> @@ -1807,14 +1807,14 @@ static int emac_down(struct emac_priv *priv)
>
> /* Update and save current stats, see emac_stats_update() for usage */
>
> - spin_lock(&priv->stats_lock);
> + spin_lock_bh(&priv->stats_lock);
>
> emac_stats_update(priv);
>
> priv->tx_stats_off = priv->tx_stats;
> priv->rx_stats_off = priv->rx_stats;
>
> - spin_unlock(&priv->stats_lock);
> + spin_unlock_bh(&priv->stats_lock);
>
> pm_runtime_put_sync(&pdev->dev);
> return 0;
> @@ -2111,7 +2111,7 @@ static int emac_resume(struct device *dev)
>
> netif_device_attach(ndev);
>
> - emac_stats_timer(&priv->stats_timer);
> + mod_timer(&priv->stats_timer, jiffies);
>
> return 0;
> }
>
> ---
> base-commit: 315f423be0d1ebe720d8fd4fa6bed68586b13d34
> change-id: 20250919-k1-ethernet-fix-lock-c99681a9aa5d
>
> Best regards,
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH net-next] net: spacemit: Make stats_lock softirq-safe
2025-09-19 12:04 ` [PATCH net-next] net: spacemit: Make stats_lock softirq-safe Vivian Wang
2025-09-19 12:25 ` Marek Szyprowski
@ 2025-09-22 19:00 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: patchwork-bot+netdevbpf @ 2025-09-22 19:00 UTC (permalink / raw)
To: Vivian Wang
Cc: andrew+netdev, davem, edumazet, kuba, pabeni, dlan,
maxime.chevallier, troy.mitchell, vadim.fedorenko, netdev,
linux-riscv, spacemit, linux-kernel, uwu, m.szyprowski
Hello:
This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:
On Fri, 19 Sep 2025 20:04:33 +0800 you wrote:
> While most of the statistics functions (emac_get_stats64() and such) are
> called with softirqs enabled, emac_stats_timer() is, as its name
> suggests, also called from a timer, i.e. called in softirq context.
>
> All of these take stats_lock. Therefore, make stats_lock softirq-safe by
> changing spin_lock() into spin_lock_bh() for the functions that get
> statistics.
>
> [...]
Here is the summary with links:
- [net-next] net: spacemit: Make stats_lock softirq-safe
https://git.kernel.org/netdev/net-next/c/35626012877b
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
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^ permalink raw reply [flat|nested] 3+ messages in thread