From dd52b3df25ed25a7a881d45d9fbfaa0ac7dec5d5 Mon Sep 17 00:00:00 2001 From: Daniel Golle Date: Tue, 4 Aug 2026 04:11:01 +0100 Subject: [PATCH] net: dsa: mt7530: serialize the regmap IRQ chip like every other user The switch register regmap is created with .disable_locking = true; every other user in this driver calls mt7530_mutex_lock()/unlock() around it, which takes priv->bus->mdio_lock, since the underlying mt7530_regmap_read()/write() issue raw, unserialized bus->read()/ write() MDIO transactions. mt7530_setup_irq() hands this same unlocked regmap straight to devm_regmap_add_irq_chip_fwnode(), whose threaded IRQ handler then calls regmap_read()/regmap_update_bits() on it without ever calling mt7530_mutex_lock(). An interrupt firing while another thread is mid-transaction on the same regmap (e.g. a paged register access, or an indirect PHY access) can interleave with the IRQ handler's own paged access and corrupt page selection on either side. Use struct regmap_irq_chip's handle_mask_sync hook to call mt7530_mutex_lock()/unlock() around the mask register write regmap-irq issues whenever a consumer of one of the mapped sub-IRQs enables, disables, requests or frees its line. This needs a per-device copy of mt7530_regmap_irq_chip, since devm_regmap_add_irq_chip_fwnode() keeps a pointer to it rather than copying it. handle_pre_irq/handle_post_irq, which would additionally cover the status read and ack write the threaded handler does directly, bracket the whole handler including its handle_nested_irq() calls. Lockdep caught this on hardware: those calls reach phy_interrupt() for the per-port PHY IRQ lines mapped through this chip, which takes phydev->lock, while phy_attach_direct() and this driver's own indirect PHY access already establish the opposite order (phydev->lock, then priv->bus->mdio_lock) elsewhere. Using them here would close that cycle, so they are not used. regmap_irq_sync_unlock() also has its own init_ack_masked path, used by this chip, which unconditionally does its own regmap_write() to ack currently-masked IRQs; that path has no per-driver hook. Together with the threaded handler's own status read and ack write, these stay unprotected -- a narrower, harder-to-hit gap than the recurring mask sync above -- and will be closed once the switch regmap moves to regmap's own locking in the driver-wide register access cleanup. Signed-off-by: Daniel Golle Reviewed-by: Andrew Lunn Link: https://patch.msgid.link/818840879e9cd20f8d568789da29b3474c8f3ab9.1785811140.git.daniel@makrotopia.org Signed-off-by: Jakub Kicinski --- drivers/net/dsa/mt7530.c | 26 +++++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c index d66d926a71e1..2b7be091c056 100644 --- a/drivers/net/dsa/mt7530.c +++ b/drivers/net/dsa/mt7530.c @@ -2319,6 +2319,21 @@ static const struct regmap_irq mt7530_irqs[] = { REGMAP_IRQ_REG_LINE(31, 32), /* ACL */ }; +/* Serialize regmap-irq's mask sync like every other regmap user */ +static int mt7530_irq_mask_sync(int index, unsigned int mask_buf_def, + unsigned int mask_buf, void *irq_drv_data) +{ + struct mt7530_priv *priv = irq_drv_data; + int ret; + + mt7530_mutex_lock(priv); + ret = regmap_update_bits(priv->regmap, MT7530_SYS_INT_EN, + mask_buf_def, ~mask_buf); + mt7530_mutex_unlock(priv); + + return ret; +} + static const struct regmap_irq_chip mt7530_regmap_irq_chip = { .name = KBUILD_MODNAME, .status_base = MT7530_SYS_INT_STS, @@ -2328,12 +2343,14 @@ static const struct regmap_irq_chip mt7530_regmap_irq_chip = { .irqs = mt7530_irqs, .num_irqs = ARRAY_SIZE(mt7530_irqs), .num_regs = 1, + .handle_mask_sync = mt7530_irq_mask_sync, }; static int mt7530_setup_irq(struct mt7530_priv *priv) { struct regmap_irq_chip_data *irq_data; + struct regmap_irq_chip *chip; struct device *dev = priv->dev; struct device_node *np = dev->of_node; int irq, ret; @@ -2353,10 +2370,17 @@ mt7530_setup_irq(struct mt7530_priv *priv) if (priv->id == ID_MT7530 || priv->id == ID_MT7621) mt7530_set(priv, MT7530_TOP_SIG_CTRL, TOP_SIG_CTRL_NORMAL); + chip = devm_kmemdup(dev, &mt7530_regmap_irq_chip, sizeof(*chip), + GFP_KERNEL); + if (!chip) + return -ENOMEM; + + chip->irq_drv_data = priv; + ret = devm_regmap_add_irq_chip_fwnode(dev, dev_fwnode(dev), priv->regmap, irq, IRQF_ONESHOT, - 0, &mt7530_regmap_irq_chip, + 0, chip, &irq_data); if (ret) return ret;