[PATCH v2 5/7] clocksource/drivers/exynos_mct: Fix uninitialized irq name warning

Will McVicker
2025-04-03T00:05:01Z

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

Signed-off-by: Will McVicker <willmcvicker@google.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],
--
2.49.0.472.ge94155a9ec-goog