From 1c10941e34c5fdc0357e46a25bd130d9cf40b925 Mon Sep 17 00:00:00 2001 From: Pierre Gondois Date: Mon, 28 Oct 2024 13:56:56 +0100 Subject: [PATCH] ACPI: CPPC: Make rmw_lock a raw_spin_lock The following BUG was triggered: ============================= [ BUG: Invalid wait context ] 6.12.0-rc2-XXX #406 Not tainted ----------------------------- kworker/1:1/62 is trying to lock: ffffff8801593030 (&cpc_ptr->rmw_lock){+.+.}-{3:3}, at: cpc_write+0xcc/0x370 other info that might help us debug this: context-{5:5} 2 locks held by kworker/1:1/62: #0: ffffff897ef5ec98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2c/0x50 #1: ffffff880154e238 (&sg_policy->update_lock){....}-{2:2}, at: sugov_update_shared+0x3c/0x280 stack backtrace: CPU: 1 UID: 0 PID: 62 Comm: kworker/1:1 Not tainted 6.12.0-rc2-g9654bd3e8806 #406 Workqueue: 0x0 (events) Call trace: dump_backtrace+0xa4/0x130 show_stack+0x20/0x38 dump_stack_lvl+0x90/0xd0 dump_stack+0x18/0x28 __lock_acquire+0x480/0x1ad8 lock_acquire+0x114/0x310 _raw_spin_lock+0x50/0x70 cpc_write+0xcc/0x370 cppc_set_perf+0xa0/0x3a8 cppc_cpufreq_fast_switch+0x40/0xc0 cpufreq_driver_fast_switch+0x4c/0x218 sugov_update_shared+0x234/0x280 update_load_avg+0x6ec/0x7b8 dequeue_entities+0x108/0x830 dequeue_task_fair+0x58/0x408 __schedule+0x4f0/0x1070 schedule+0x54/0x130 worker_thread+0xc0/0x2e8 kthread+0x130/0x148 ret_from_fork+0x10/0x20 sugov_update_shared() locks a raw_spinlock while cpc_write() locks a spinlock. To have a correct wait-type order, update rmw_lock to a raw spinlock and ensure that interrupts will be disabled on the CPU holding it. Fixes: 60949b7b8054 ("ACPI: CPPC: Fix MASK_VAL() usage") Signed-off-by: Pierre Gondois Link: https://patch.msgid.link/20241028125657.1271512-1-pierre.gondois@arm.com [ rjw: Changelog edits ] Signed-off-by: Rafael J. Wysocki --- drivers/acpi/cppc_acpi.c | 9 +++++---- include/acpi/cppc_acpi.h | 2 +- 2 files changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index c3fc2c05d868..1a40f0514eaa 100644 --- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -867,7 +867,7 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr) /* Store CPU Logical ID */ cpc_ptr->cpu_id = pr->id; - spin_lock_init(&cpc_ptr->rmw_lock); + raw_spin_lock_init(&cpc_ptr->rmw_lock); /* Parse PSD data for this CPU */ ret = acpi_get_psd(cpc_ptr, handle); @@ -1087,6 +1087,7 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val) int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu); struct cpc_reg *reg = ®_res->cpc_entry.reg; struct cpc_desc *cpc_desc; + unsigned long flags; size = GET_BIT_WIDTH(reg); @@ -1126,7 +1127,7 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val) return -ENODEV; } - spin_lock(&cpc_desc->rmw_lock); + raw_spin_lock_irqsave(&cpc_desc->rmw_lock, flags); switch (size) { case 8: prev_val = readb_relaxed(vaddr); @@ -1141,7 +1142,7 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val) prev_val = readq_relaxed(vaddr); break; default: - spin_unlock(&cpc_desc->rmw_lock); + raw_spin_unlock_irqrestore(&cpc_desc->rmw_lock, flags); return -EFAULT; } val = MASK_VAL_WRITE(reg, prev_val, val); @@ -1174,7 +1175,7 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val) } if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) - spin_unlock(&cpc_desc->rmw_lock); + raw_spin_unlock_irqrestore(&cpc_desc->rmw_lock, flags); return ret_val; } diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h index 76e44e102780..62d368bcd9ec 100644 --- a/include/acpi/cppc_acpi.h +++ b/include/acpi/cppc_acpi.h @@ -65,7 +65,7 @@ struct cpc_desc { int write_cmd_status; int write_cmd_id; /* Lock used for RMW operations in cpc_write() */ - spinlock_t rmw_lock; + raw_spinlock_t rmw_lock; struct cpc_register_resource cpc_regs[MAX_CPC_REG_ENT]; struct acpi_psd_package domain_info; struct kobject kobj;