diff options
| author | K Prateek Nayak <kprateek.nayak@amd.com> | 2026-03-16 08:18:49 +0000 |
|---|---|---|
| committer | Mario Limonciello (AMD) <superm1@kernel.org> | 2026-04-02 11:30:24 -0500 |
| commit | c03791085adcd61fa9b766ab303c7d0941d7378d (patch) | |
| tree | cea586c0fae5947a773e5bb8f61e8872354bf4d2 /include/linux | |
| parent | 86d71f1d7686cecebbafb371ad58c6ad7f80a93a (diff) | |
cpufreq: Pass the policy to cpufreq_driver->adjust_perf()
cpufreq_cpu_get() can sleep on PREEMPT_RT in presence of concurrent
writer(s), however amd-pstate depends on fetching the cpudata via the
policy's driver data which necessitates grabbing the reference.
Since schedutil governor can call "cpufreq_driver->update_perf()"
during sched_tick/enqueue/dequeue with rq_lock held and IRQs disabled,
fetching the policy object using the cpufreq_cpu_get() helper in the
scheduler fast-path leads to "BUG: scheduling while atomic" on
PREEMPT_RT [1].
Pass the cached cpufreq policy object in sg_policy to the update_perf()
instead of just the CPU. The CPU can be inferred using "policy->cpu".
The lifetime of cpufreq_policy object outlasts that of the governor and
the cpufreq driver (allocated when the CPU is onlined and only reclaimed
when the CPU is offlined / the CPU device is removed) which makes it
safe to be referenced throughout the governor's lifetime.
Closes:https://lore.kernel.org/all/20250731092316.3191-1-spasswolf@web.de/ [1]
Fixes: 1d215f0319c2 ("cpufreq: amd-pstate: Add fast switch function for AMD P-State")
Reported-by: Bert Karwatzki <spasswolf@web.de>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Acked-by: Gary Guo <gary@garyguo.net> # Rust
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20260316081849.19368-3-kprateek.nayak@amd.com
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/cpufreq.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index cc894fc38971..4317c5a312bd 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -372,7 +372,7 @@ struct cpufreq_driver { * conditions) scale invariance can be disabled, which causes the * schedutil governor to fall back to the latter. */ - void (*adjust_perf)(unsigned int cpu, + void (*adjust_perf)(struct cpufreq_policy *policy, unsigned long min_perf, unsigned long target_perf, unsigned long capacity); @@ -617,7 +617,7 @@ struct cpufreq_governor { /* Pass a target to the cpufreq driver */ unsigned int cpufreq_driver_fast_switch(struct cpufreq_policy *policy, unsigned int target_freq); -void cpufreq_driver_adjust_perf(unsigned int cpu, +void cpufreq_driver_adjust_perf(struct cpufreq_policy *policy, unsigned long min_perf, unsigned long target_perf, unsigned long capacity); |