From: Sumit Gupta Date: Thu, 26 Feb 2026 11:59:11 +0000 (+0530) Subject: arm64: topology: Fix false warning in counters_read_on_cpu() for same-CPU reads X-Git-Tag: v7.0-rc2~17^2 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=df6e4ab654dc482c1d45776257a62ac10e14086c;p=thirdparty%2Flinux.git arm64: topology: Fix false warning in counters_read_on_cpu() for same-CPU reads The counters_read_on_cpu() function warns when called with IRQs disabled to prevent deadlock in smp_call_function_single(). However, this warning is spurious when reading counters on the current CPU, since no IPI is needed for same CPU reads. Commit 12eb8f4fff24 ("cpufreq: CPPC: Update FIE arch_freq_scale in ticks for non-PCC regs") changed the CPPC Frequency Invariance Engine to read AMU counters directly from the scheduler tick for non-PCC register spaces (like FFH), instead of deferring to a kthread. This means counters_read_on_cpu() is now called with IRQs disabled from the tick handler, triggering the warning. Fix this by restructuring the logic: when IRQs are disabled (tick context), call the function directly for same-CPU reads. Otherwise use smp_call_function_single(). Fixes: 997c021abc6e ("cpufreq: CPPC: Update FIE arch_freq_scale in ticks for non-PCC regs") Suggested-by: Will Deacon Signed-off-by: Sumit Gupta Signed-off-by: Will Deacon --- diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index 3fe1faab0362..b32f13358fbb 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -400,16 +400,25 @@ static inline int counters_read_on_cpu(int cpu, smp_call_func_t func, u64 *val) { /* - * Abort call on counterless CPU or when interrupts are - * disabled - can lead to deadlock in smp sync call. + * Abort call on counterless CPU. */ if (!cpu_has_amu_feat(cpu)) return -EOPNOTSUPP; - if (WARN_ON_ONCE(irqs_disabled())) - return -EPERM; - - smp_call_function_single(cpu, func, val, 1); + if (irqs_disabled()) { + /* + * When IRQs are disabled (tick path: sched_tick -> + * topology_scale_freq_tick or cppc_scale_freq_tick), only local + * CPU counter reads are allowed. Remote CPU counter read would + * require smp_call_function_single() which is unsafe with IRQs + * disabled. + */ + if (WARN_ON_ONCE(cpu != smp_processor_id())) + return -EPERM; + func(val); + } else { + smp_call_function_single(cpu, func, val, 1); + } return 0; }