linux-kernel - Re: [PATCH 4/6] clocksource/drivers/exynos_mct: Fix uninitialized irq name warning

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Message-ID: <aFqmhDQnlUHh4vLY@mai.linaro.org>
Date: Tue, 24 Jun 2025 15:22:12 +0200
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Will McVicker <willmcvicker@...gle.com>
Cc: Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>, Thomas Gleixner <tglx@...utronix.de>,
	Krzysztof Kozlowski <krzk@...nel.org>,
	Alim Akhtar <alim.akhtar@...sung.com>,
	Rob Herring <robh@...nel.org>,
	Saravana Kannan <saravanak@...gle.com>,
	Donghoon Yu <hoony.yu@...sung.com>,
	Hosung Kim <hosung0.kim@...sung.com>, kernel-team@...roid.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	John Stultz <jstultz@...gle.com>,
	Youngmin Nam <youngmin.nam@...sung.com>,
	Peter Griffin <peter.griffin@...aro.org>,
	Tudor Ambarus <tudor.ambarus@...aro.org>,
	André Draszik <andre.draszik@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>,
	linux-samsung-soc@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 4/6] clocksource/drivers/exynos_mct: Fix uninitialized
 irq name warning

On Wed, Jun 18, 2025 at 02:08:41PM -0700, Will McVicker wrote:
> The Exynos MCT driver doesn't set the clocksource name until the CPU
> hotplug state is setup which happens after the IRQs are requested. This
> results in an empty IRQ name which leads to the below warning at
> proc_create() time. When this happens, the userdata partition fails to
> mount and the device gets stuck in an endless loop printing the error:
> 
>   root '/dev/disk/by-partlabel/userdata' doesn't exist or does not contain a /dev.
> 
> To fix this, we just need to initialize the name before requesting the
> IRQs.
> 
> Warning from Pixel 6 kernel log:
> 
> [  T430] name len 0
> [  T430] WARNING: CPU: 6 PID: 430 at fs/proc/generic.c:407 __proc_create+0x258/0x2b4
> [  T430] Modules linked in: dwc3_exynos(E+)
> [  T430]  ufs_exynos(E+) phy_exynos_ufs(E)
> [  T430]  phy_exynos5_usbdrd(E) exynos_usi(E+) exynos_mct(E+) s3c2410_wdt(E)
> [  T430]  arm_dsu_pmu(E) simplefb(E)
> [  T430] CPU: 6 UID: 0 PID: 430 Comm: (udev-worker) Tainted:
>          ... 6.14.0-next-20250331-4k-00008-g59adf909e40e #1 ...
> [  T430] Tainted: [W]=WARN, [E]=UNSIGNED_MODULE
> [  T430] Hardware name: Raven (DT)
> [...]
> [  T430] Call trace:
> [  T430]  __proc_create+0x258/0x2b4 (P)
> [  T430]  proc_mkdir+0x40/0xa0
> [  T430]  register_handler_proc+0x118/0x140
> [  T430]  __setup_irq+0x460/0x6d0
> [  T430]  request_threaded_irq+0xcc/0x1b0
> [  T430]  mct_init_dt+0x244/0x604 [exynos_mct ...]
> [  T430]  mct_init_spi+0x18/0x34 [exynos_mct ...]
> [  T430]  exynos4_mct_probe+0x30/0x4c [exynos_mct ...]
> [  T430]  platform_probe+0x6c/0xe4
> [  T430]  really_probe+0xf4/0x38c
> [...]
> [  T430]  driver_register+0x6c/0x140
> [  T430]  __platform_driver_register+0x28/0x38
> [  T430]  exynos4_mct_driver_init+0x24/0xfe8 [exynos_mct ...]
> [  T430]  do_one_initcall+0x84/0x3c0
> [  T430]  do_init_module+0x58/0x208
> [  T430]  load_module+0x1de0/0x2500
> [  T430]  init_module_from_file+0x8c/0xdc
> 
> Reviewed-by: Peter Griffin <peter.griffin@...aro.org>
> Reviewed-by: Youngmin Nam <youngmin.nam@...sung.com>
> Tested-by: Youngmin Nam <youngmin.nam@...sung.com>
> Signed-off-by: Will McVicker <willmcvicker@...gle.com>
> ---
>  drivers/clocksource/exynos_mct.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
> index a5ef7d64b1c2..62febeb4e1de 100644
> --- a/drivers/clocksource/exynos_mct.c
> +++ b/drivers/clocksource/exynos_mct.c
> @@ -465,8 +465,6 @@ static int exynos4_mct_starting_cpu(unsigned int cpu)
>  		per_cpu_ptr(&percpu_mct_tick, cpu);
>  	struct clock_event_device *evt = &mevt->evt;
>  
> -	snprintf(mevt->name, sizeof(mevt->name), "mct_tick%d", cpu);
> -
>  	evt->name = mevt->name;
>  	evt->cpumask = cpumask_of(cpu);
>  	evt->set_next_event = exynos4_tick_set_next_event;
> @@ -567,6 +565,14 @@ static int __init exynos4_timer_interrupts(struct device_node *np,
>  	for (i = MCT_L0_IRQ; i < nr_irqs; i++)
>  		mct_irqs[i] = irq_of_parse_and_map(np, i);
>  
> +	for_each_possible_cpu(cpu) {
> +		struct mct_clock_event_device *mevt =
> +		    per_cpu_ptr(&percpu_mct_tick, cpu);
> +
> +		snprintf(mevt->name, sizeof(mevt->name), "mct_tick%d",
> +			 cpu);
> +	}
> +
>  	if (mct_int_type == MCT_INT_PPI) {
>  
>  		err = request_percpu_irq(mct_irqs[MCT_L0_IRQ],
> -- 
> 2.50.0.rc2.761.g2dc52ea45b-goog
> 

There are too many for_each_possible_cpu() loops in this function.

Why not move the per cpu relevant code in the hotplug callbacks ?


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