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net: dsa: mt7530: fix .get_stats64 sleeping in atomic context

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The .get_stats64 callback runs in atomic context, but on
MDIO-connected switches every register read acquires the MDIO bus
mutex, which can sleep:
[   12.645973] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:609
[   12.654442] in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 759, name: grep
[   12.663377] preempt_count: 0, expected: 0
[   12.667410] RCU nest depth: 1, expected: 0
[   12.671511] INFO: lockdep is turned off.
[   12.675441] CPU: 0 UID: 0 PID: 759 Comm: grep Tainted: G S      W           7.0.0+ #0 PREEMPT
[   12.675453] Tainted: [S]=CPU_OUT_OF_SPEC, [W]=WARN
[   12.675456] Hardware name: Bananapi BPI-R64 (DT)
[   12.675459] Call trace:
[   12.675462]  show_stack+0x14/0x1c (C)
[   12.675477]  dump_stack_lvl+0x68/0x8c
[   12.675487]  dump_stack+0x14/0x1c
[   12.675495]  __might_resched+0x14c/0x220
[   12.675504]  __might_sleep+0x44/0x80
[   12.675511]  __mutex_lock+0x50/0xb10
[   12.675523]  mutex_lock_nested+0x20/0x30
[   12.675532]  mt7530_get_stats64+0x40/0x2ac
[   12.675542]  dsa_user_get_stats64+0x2c/0x40
[   12.675553]  dev_get_stats+0x44/0x1e0
[   12.675564]  dev_seq_printf_stats+0x24/0xe0
[   12.675575]  dev_seq_show+0x14/0x3c
[   12.675583]  seq_read_iter+0x37c/0x480
[   12.675595]  seq_read+0xd0/0xec
[   12.675605]  proc_reg_read+0x94/0xe4
[   12.675615]  vfs_read+0x98/0x29c
[   12.675625]  ksys_read+0x54/0xdc
[   12.675633]  __arm64_sys_read+0x18/0x20
[   12.675642]  invoke_syscall.constprop.0+0x54/0xec
[   12.675653]  do_el0_svc+0x3c/0xb4
[   12.675662]  el0_svc+0x38/0x200
[   12.675670]  el0t_64_sync_handler+0x98/0xdc
[   12.675679]  el0t_64_sync+0x158/0x15c

For MDIO-connected switches, poll MIB counters asynchronously using a
delayed workqueue every second and let .get_stats64 return the cached
values under a spinlock. A mod_delayed_work() call on each read
triggers an immediate refresh so counters stay responsive when queried
more frequently.

MMIO-connected switches (MT7988, EN7581, AN7583) are not affected
because their regmap does not sleep, so they continue to read MIB
counters directly in .get_stats64.

Fixes: 88c810f35e ("net: dsa: mt7530: implement .get_stats64")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Acked-by: Chester A. Unal <chester.a.unal@arinc9.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/6940b913da2c29156f0feff74b678d3c526ee84c.1777719253.git.daniel@makrotopia.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Daniel Golle
2026-05-02 11:55:02 +01:00
committed by Jakub Kicinski
parent a6039776c7
commit 07d9958739
2 changed files with 80 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

75
drivers/net/dsa/mt7530.c
View File

@@ -25,6 +25,9 @@
#include "mt7530.h"
#define MT7530_STATS_POLL_INTERVAL (1 * HZ)
#define MT7530_STATS_RATE_LIMIT (HZ / 10)
static struct mt753x_pcs *pcs_to_mt753x_pcs(struct phylink_pcs *pcs)
{
return container_of(pcs, struct mt753x_pcs, pcs);
@@ -906,10 +909,9 @@ static void mt7530_get_rmon_stats(struct dsa_switch *ds, int port,
*ranges = mt7530_rmon_ranges;
}
static void mt7530_get_stats64(struct dsa_switch *ds, int port,
struct rtnl_link_stats64 *storage)
static void mt7530_read_port_stats64(struct mt7530_priv *priv, int port,
struct rtnl_link_stats64 *storage)
{
struct mt7530_priv *priv = ds->priv;
uint64_t data;
/* MIB counter doesn't provide a FramesTransmittedOK but instead
@@ -951,6 +953,54 @@ static void mt7530_get_stats64(struct dsa_switch *ds, int port,
&storage->rx_crc_errors);
}
static void mt7530_stats_refresh(struct mt7530_priv *priv)
{
struct rtnl_link_stats64 stats = {};
struct dsa_port *dp;
int port;
dsa_switch_for_each_user_port(dp, priv->ds) {
port = dp->index;
mt7530_read_port_stats64(priv, port, &stats);
spin_lock_bh(&priv->stats_lock);
priv->ports[port].stats = stats;
priv->stats_last = jiffies;
spin_unlock_bh(&priv->stats_lock);
}
}
static void mt7530_stats_poll(struct work_struct *work)
{
struct mt7530_priv *priv = container_of(work, struct mt7530_priv,
stats_work.work);
mt7530_stats_refresh(priv);
schedule_delayed_work(&priv->stats_work,
MT7530_STATS_POLL_INTERVAL);
}
static void mt7530_get_stats64(struct dsa_switch *ds, int port,
struct rtnl_link_stats64 *storage)
{
struct mt7530_priv *priv = ds->priv;
bool refresh;
if (priv->bus) {
spin_lock_bh(&priv->stats_lock);
*storage = priv->ports[port].stats;
refresh = time_after(jiffies, priv->stats_last +
MT7530_STATS_RATE_LIMIT);
spin_unlock_bh(&priv->stats_lock);
if (refresh)
mod_delayed_work(system_percpu_wq,
&priv->stats_work, 0);
} else {
mt7530_read_port_stats64(priv, port, storage);
}
}
static void mt7530_get_eth_ctrl_stats(struct dsa_switch *ds, int port,
struct ethtool_eth_ctrl_stats *ctrl_stats)
{
@@ -3137,9 +3187,24 @@ mt753x_setup(struct dsa_switch *ds)
if (ret && priv->irq_domain)
mt7530_free_mdio_irq(priv);
if (!ret && priv->bus) {
mt7530_stats_refresh(priv);
schedule_delayed_work(&priv->stats_work,
MT7530_STATS_POLL_INTERVAL);
}
return ret;
}
static void
mt753x_teardown(struct dsa_switch *ds)
{
struct mt7530_priv *priv = ds->priv;
if (priv->bus)
cancel_delayed_work_sync(&priv->stats_work);
}
static int mt753x_set_mac_eee(struct dsa_switch *ds, int port,
struct ethtool_keee *e)
{
@@ -3257,6 +3322,7 @@ static int mt7988_setup(struct dsa_switch *ds)
static const struct dsa_switch_ops mt7530_switch_ops = {
.get_tag_protocol = mtk_get_tag_protocol,
.setup = mt753x_setup,
.teardown = mt753x_teardown,
.preferred_default_local_cpu_port = mt753x_preferred_default_local_cpu_port,
.get_strings = mt7530_get_strings,
.get_ethtool_stats = mt7530_get_ethtool_stats,
@@ -3395,6 +3461,9 @@ mt7530_probe_common(struct mt7530_priv *priv)
priv->ds->ops = &mt7530_switch_ops;
priv->ds->phylink_mac_ops = &mt753x_phylink_mac_ops;
mutex_init(&priv->reg_mutex);
spin_lock_init(&priv->stats_lock);
INIT_DELAYED_WORK(&priv->stats_work, mt7530_stats_poll);
dev_set_drvdata(dev, priv);
return 0;

8
drivers/net/dsa/mt7530.h
View File

@@ -796,6 +796,7 @@ struct mt7530_fdb {
* @pvid: The VLAN specified is to be considered a PVID at ingress. Any
* untagged frames will be assigned to the related VLAN.
* @sgmii_pcs: Pointer to PCS instance for SerDes ports
* @stats: Cached port statistics for MDIO-connected switches
*/
struct mt7530_port {
bool enable;
@@ -803,6 +804,7 @@ struct mt7530_port {
u32 pm;
u16 pvid;
struct phylink_pcs *sgmii_pcs;
struct rtnl_link_stats64 stats;
};
/* Port 5 mode definitions of the MT7530 switch */
@@ -875,6 +877,9 @@ struct mt753x_info {
* @create_sgmii: Pointer to function creating SGMII PCS instance(s)
* @active_cpu_ports: Holding the active CPU ports
* @mdiodev: The pointer to the MDIO device structure
* @stats_lock: Protects cached per-port stats from concurrent access
* @stats_work: Delayed work for polling MIB counters on MDIO switches
* @stats_last: Jiffies timestamp of last MIB counter poll
*/
struct mt7530_priv {
struct device *dev;
@@ -900,6 +905,9 @@ struct mt7530_priv {
int (*create_sgmii)(struct mt7530_priv *priv);
u8 active_cpu_ports;
struct mdio_device *mdiodev;
spinlock_t stats_lock; /* protects cached stats counters */
struct delayed_work stats_work;
unsigned long stats_last;
};
struct mt7530_hw_vlan_entry {