linux-kernel - [PATCH] soc: samsung: exynos-pmu: Fix for CONFIG_DEBUG

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Message-ID: <20250905162446.88987-1-smostafa@google.com>
Date: Fri,  5 Sep 2025 16:24:46 +0000
From: Mostafa Saleh <smostafa@...gle.com>
To: linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Cc: krzk@...nel.org, alim.akhtar@...sung.com, 
	Mostafa Saleh <smostafa@...gle.com>, Peter Griffin <peter.griffin@...aro.org>, 
	"André Draszik" <andre.draszik@...aro.org>
Subject: [PATCH] soc: samsung: exynos-pmu: Fix for CONFIG_DEBUG_PREEMPT

Booting the kernel on Pixel-6 with `CONFIG_DEBUG_PREEMPT` prints the
following WARN:

[    0.784187][    T1] BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1
[    0.784328][    T1] caller is debug_smp_processor_id+0x20/0x30
[    0.784433][    T1] CPU: 6 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.17.0-rc4-gd69eb204c255 #1 PREEMPT
[    0.784439][    T1] Hardware name: Oriole (DT)
[    0.784441][    T1] Call trace:
[    0.784443][    T1]  show_stack+0x34/0xa0 (C)
[    0.784453][    T1]  dump_stack_lvl+0x7c/0xb0
[    0.784460][    T1]  dump_stack+0x18/0x24
[    0.784464][    T1]  check_preemption_disabled+0xf8/0x100
[    0.784470][    T1]  debug_smp_processor_id+0x20/0x30
[    0.784476][    T1]  gs101_cpuhp_pmu_online+0x40/0x108
[    0.784483][    T1]  cpuhp_invoke_callback+0x188/0x2d8
[    0.784490][    T1]  cpuhp_issue_call+0xec/0x240
[    0.784494][    T1]  __cpuhp_setup_state_cpuslocked+0x140/0x2c0
[    0.784499][    T1]  __cpuhp_setup_state+0x58/0x88
[    0.784504][    T1]  exynos_pmu_probe+0x2a4/0x380
[    0.784508][    T1]  platform_probe+0x64/0xd0
[    0.784516][    T1]  really_probe+0xd0/0x3b0
[    0.784520][    T1]  __driver_probe_device+0x8c/0x170
[    0.784524][    T1]  driver_probe_device+0x44/0x140
[    0.784528][    T1]  __device_attach_driver+0xd8/0x180
[    0.784532][    T1]  bus_for_each_drv+0x90/0xf8
[    0.784536][    T1]  __device_attach+0xa8/0x1d0
[    0.784540][    T1]  device_initial_probe+0x1c/0x30
[    0.784544][    T1]  bus_probe_device+0xb4/0xc0
[    0.784547][    T1]  device_add+0x4d0/0x700
[    0.784550][    T1]  of_device_add+0x4c/0x78
[    0.784556][    T1]  of_platform_device_create_pdata+0x9c/0x148
[    0.784560][    T1]  of_platform_bus_create+0x1d0/0x370
[    0.784563][    T1]  of_platform_bus_create+0x234/0x370
[    0.784567][    T1]  of_platform_populate+0x84/0x178
[    0.784571][    T1]  of_platform_default_populate_init+0xf0/0x120
[    0.784579][    T1]  do_one_initcall+0x68/0x2d0
[    0.784585][    T1]  kernel_init_freeable+0x2d8/0x358
[    0.784589][    T1]  kernel_init+0x28/0x168
[    0.784595][    T1]  ret_from_fork+0x10/0x20

As this value is only read once, it doesn't require to be stable, so
just use "raw_smp_processor_id" instead.

Cc: Peter Griffin <peter.griffin@...aro.org>
Cc: André Draszik <andre.draszik@...aro.org>

Signed-off-by: Mostafa Saleh <smostafa@...gle.com>
---
 drivers/soc/samsung/exynos-pmu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/samsung/exynos-pmu.c b/drivers/soc/samsung/exynos-pmu.c
index a77288f49d24..338f4758a089 100644
--- a/drivers/soc/samsung/exynos-pmu.c
+++ b/drivers/soc/samsung/exynos-pmu.c
@@ -338,7 +338,7 @@ EXPORT_SYMBOL_GPL(exynos_get_pmu_regmap_by_phandle);
 
 static int gs101_cpuhp_pmu_online(unsigned int cpu)
 {
-	unsigned int cpuhint = smp_processor_id();
+	unsigned int cpuhint = raw_smp_processor_id();
 	u32 reg, mask;
 
 	/* clear cpu inform hint */
@@ -361,7 +361,7 @@ static int gs101_cpuhp_pmu_online(unsigned int cpu)
 static int gs101_cpuhp_pmu_offline(unsigned int cpu)
 {
 	u32 reg, mask;
-	unsigned int cpuhint = smp_processor_id();
+	unsigned int cpuhint = raw_smp_processor_id();
 
 	/* set cpu inform hint */
 	regmap_write(pmu_context->pmureg, GS101_CPU_INFORM(cpuhint),
-- 
2.51.0.355.g5224444f11-goog