From: Marc Zyngier maz@kernel.org
[ Upstream commit 0a66d6f90cf7d704c6a0f663f7058099eb8c97b0 ]
Running a lockedp-enabled kernel on a vim3l board (Amlogic SM1) leads to the following splat:
[ 13.557138] WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected [ 13.587485] ip/456 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: [ 13.625922] ffff000059908cf0 (&irq_desc_lock_class){-.-.}-{2:2}, at: __setup_irq+0xf8/0x8d8 [ 13.632273] which would create a new lock dependency: [ 13.637272] (&irq_desc_lock_class){-.-.}-{2:2} -> (&ctl->lock){+.+.}-{2:2} [ 13.644209] [ 13.644209] but this new dependency connects a HARDIRQ-irq-safe lock: [ 13.654122] (&irq_desc_lock_class){-.-.}-{2:2} [ 13.654125] [ 13.654125] ... which became HARDIRQ-irq-safe at: [ 13.664759] lock_acquire+0xec/0x368 [ 13.666926] _raw_spin_lock+0x60/0x88 [ 13.669979] handle_fasteoi_irq+0x30/0x178 [ 13.674082] generic_handle_irq+0x38/0x50 [ 13.678098] __handle_domain_irq+0x6c/0xc8 [ 13.682209] gic_handle_irq+0x5c/0xb0 [ 13.685872] el1_irq+0xd0/0x180 [ 13.689010] arch_cpu_idle+0x40/0x220 [ 13.692732] default_idle_call+0x54/0x60 [ 13.696677] do_idle+0x23c/0x2e8 [ 13.699903] cpu_startup_entry+0x30/0x50 [ 13.703852] rest_init+0x1e0/0x2b4 [ 13.707301] arch_call_rest_init+0x18/0x24 [ 13.711449] start_kernel+0x4ec/0x51c [ 13.715167] [ 13.715167] to a HARDIRQ-irq-unsafe lock: [ 13.722426] (&ctl->lock){+.+.}-{2:2} [ 13.722430] [ 13.722430] ... which became HARDIRQ-irq-unsafe at: [ 13.732319] ... [ 13.732324] lock_acquire+0xec/0x368 [ 13.735985] _raw_spin_lock+0x60/0x88 [ 13.739452] meson_gpio_irq_domain_alloc+0xcc/0x290 [ 13.744392] irq_domain_alloc_irqs_hierarchy+0x24/0x60 [ 13.749586] __irq_domain_alloc_irqs+0x160/0x2f0 [ 13.754254] irq_create_fwspec_mapping+0x118/0x320 [ 13.759073] irq_create_of_mapping+0x78/0xa0 [ 13.763360] of_irq_get+0x6c/0x80 [ 13.766701] of_mdiobus_register_phy+0x10c/0x238 [of_mdio] [ 13.772227] of_mdiobus_register+0x158/0x380 [of_mdio] [ 13.777388] mdio_mux_init+0x180/0x2e8 [mdio_mux] [ 13.782128] g12a_mdio_mux_probe+0x290/0x398 [mdio_mux_meson_g12a] [ 13.788349] platform_drv_probe+0x5c/0xb0 [ 13.792379] really_probe+0xe4/0x448 [ 13.795979] driver_probe_device+0xe8/0x140 [ 13.800189] __device_attach_driver+0x94/0x120 [ 13.804639] bus_for_each_drv+0x84/0xd8 [ 13.808474] __device_attach+0xe4/0x168 [ 13.812361] device_initial_probe+0x1c/0x28 [ 13.816592] bus_probe_device+0xa4/0xb0 [ 13.820430] deferred_probe_work_func+0xa8/0x100 [ 13.825064] process_one_work+0x264/0x688 [ 13.829088] worker_thread+0x4c/0x458 [ 13.832768] kthread+0x154/0x158 [ 13.836018] ret_from_fork+0x10/0x18 [ 13.839612] [ 13.839612] other info that might help us debug this: [ 13.839612] [ 13.850354] Possible interrupt unsafe locking scenario: [ 13.850354] [ 13.855720] CPU0 CPU1 [ 13.858774] ---- ---- [ 13.863242] lock(&ctl->lock); [ 13.866330] local_irq_disable(); [ 13.872233] lock(&irq_desc_lock_class); [ 13.878705] lock(&ctl->lock); [ 13.884297] <Interrupt> [ 13.886857] lock(&irq_desc_lock_class); [ 13.891014] [ 13.891014] *** DEADLOCK ***
The issue can occur when CPU1 is doing something like irq_set_type() and CPU0 performing an interrupt allocation, for example. Taking an interrupt (like the one being reconfigured) would lead to a deadlock.
A solution to this is:
- Reorder the locking so that meson_gpio_irq_update_bits takes the lock itself at all times, instead of relying on the caller to lock or not, hence making the RMW sequence atomic,
- Rework the critical section in meson_gpio_irq_request_channel to only cover the allocation itself, and let the gpio_irq_sel_pin callback deal with its own locking if required,
- Take the private spin-lock with interrupts disabled at all times
Reviewed-by: Jerome Brunet jbrunet@baylibre.com Signed-off-by: Marc Zyngier maz@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/irqchip/irq-meson-gpio.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/drivers/irqchip/irq-meson-gpio.c b/drivers/irqchip/irq-meson-gpio.c index ccc7f823911bd..bc7aebcc96e9c 100644 --- a/drivers/irqchip/irq-meson-gpio.c +++ b/drivers/irqchip/irq-meson-gpio.c @@ -144,12 +144,17 @@ struct meson_gpio_irq_controller { static void meson_gpio_irq_update_bits(struct meson_gpio_irq_controller *ctl, unsigned int reg, u32 mask, u32 val) { + unsigned long flags; u32 tmp;
+ spin_lock_irqsave(&ctl->lock, flags); + tmp = readl_relaxed(ctl->base + reg); tmp &= ~mask; tmp |= val; writel_relaxed(tmp, ctl->base + reg); + + spin_unlock_irqrestore(&ctl->lock, flags); }
static void meson_gpio_irq_init_dummy(struct meson_gpio_irq_controller *ctl) @@ -196,14 +201,15 @@ meson_gpio_irq_request_channel(struct meson_gpio_irq_controller *ctl, unsigned long hwirq, u32 **channel_hwirq) { + unsigned long flags; unsigned int idx;
- spin_lock(&ctl->lock); + spin_lock_irqsave(&ctl->lock, flags);
/* Find a free channel */ idx = find_first_zero_bit(ctl->channel_map, NUM_CHANNEL); if (idx >= NUM_CHANNEL) { - spin_unlock(&ctl->lock); + spin_unlock_irqrestore(&ctl->lock, flags); pr_err("No channel available\n"); return -ENOSPC; } @@ -211,6 +217,8 @@ meson_gpio_irq_request_channel(struct meson_gpio_irq_controller *ctl, /* Mark the channel as used */ set_bit(idx, ctl->channel_map);
+ spin_unlock_irqrestore(&ctl->lock, flags); + /* * Setup the mux of the channel to route the signal of the pad * to the appropriate input of the GIC @@ -225,8 +233,6 @@ meson_gpio_irq_request_channel(struct meson_gpio_irq_controller *ctl, */ *channel_hwirq = &(ctl->channel_irqs[idx]);
- spin_unlock(&ctl->lock); - pr_debug("hwirq %lu assigned to channel %d - irq %u\n", hwirq, idx, **channel_hwirq);
@@ -287,13 +293,9 @@ static int meson_gpio_irq_type_setup(struct meson_gpio_irq_controller *ctl, val |= REG_EDGE_POL_LOW(params, idx); }
- spin_lock(&ctl->lock); - meson_gpio_irq_update_bits(ctl, REG_EDGE_POL, REG_EDGE_POL_MASK(params, idx), val);
- spin_unlock(&ctl->lock); - return 0; }