From 33db8c97b4cfa0328054fb755dfbcd6e7f3c7a9d Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Mon, 9 Jun 2025 14:26:54 +0530 Subject: rust: Use CpuId in place of raw CPU numbers MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Use the newly defined `CpuId` abstraction instead of raw CPU numbers. This also fixes a doctest failure for configurations where `nr_cpu_ids < 4`. The C `cpumask_{set|clear}_cpu()` APIs emit a warning when given an invalid CPU number — but only if `CONFIG_DEBUG_PER_CPU_MAPS=y` is set. Meanwhile, `cpumask_weight()` only considers CPUs up to `nr_cpu_ids`, which can cause inconsistencies: a CPU number greater than `nr_cpu_ids` may be set in the mask, yet the weight calculation won't reflect it. This leads to doctest failures when `nr_cpu_ids < 4`, as the test tries to set CPUs 2 and 3: rust_doctest_kernel_cpumask_rs_0.location: rust/kernel/cpumask.rs:180 rust_doctest_kernel_cpumask_rs_0: ASSERTION FAILED at rust/kernel/cpumask.rs:190 Fixes: 8961b8cb3099 ("rust: cpumask: Add initial abstractions") Reported-by: Miguel Ojeda Closes: https://lore.kernel.org/rust-for-linux/CANiq72k3ozKkLMinTLQwvkyg9K=BeRxs1oYZSKhJHY-veEyZdg@mail.gmail.com/ Reported-by: Andreas Hindborg Closes: https://lore.kernel.org/all/87qzzy3ric.fsf@kernel.org/ Suggested-by: Boqun Feng Signed-off-by: Viresh Kumar Reviewed-by: Boqun Feng --- rust/kernel/cpufreq.rs | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) (limited to 'rust/kernel/cpufreq.rs') diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs index 9b995f18aac6..11b03e9d7e89 100644 --- a/rust/kernel/cpufreq.rs +++ b/rust/kernel/cpufreq.rs @@ -10,6 +10,7 @@ use crate::{ clk::Hertz, + cpu::CpuId, cpumask, device::{Bound, Device}, devres::Devres, @@ -465,8 +466,9 @@ impl Policy { /// Returns the primary CPU for the [`Policy`]. #[inline] - pub fn cpu(&self) -> u32 { - self.as_ref().cpu + pub fn cpu(&self) -> CpuId { + // SAFETY: The C API guarantees that `cpu` refers to a valid CPU number. + unsafe { CpuId::from_u32_unchecked(self.as_ref().cpu) } } /// Returns the minimum frequency for the [`Policy`]. @@ -525,7 +527,7 @@ impl Policy { #[inline] pub fn generic_get(&self) -> Result { // SAFETY: By the type invariant, the pointer stored in `self` is valid. - Ok(unsafe { bindings::cpufreq_generic_get(self.cpu()) }) + Ok(unsafe { bindings::cpufreq_generic_get(u32::from(self.cpu())) }) } /// Provides a wrapper to the register with energy model using the OPP core. @@ -678,9 +680,9 @@ impl Policy { struct PolicyCpu<'a>(&'a mut Policy); impl<'a> PolicyCpu<'a> { - fn from_cpu(cpu: u32) -> Result { + fn from_cpu(cpu: CpuId) -> Result { // SAFETY: It is safe to call `cpufreq_cpu_get` for any valid CPU. - let ptr = from_err_ptr(unsafe { bindings::cpufreq_cpu_get(cpu) })?; + let ptr = from_err_ptr(unsafe { bindings::cpufreq_cpu_get(u32::from(cpu)) })?; Ok(Self( // SAFETY: The `ptr` is guaranteed to be valid and remains valid for the lifetime of @@ -1266,7 +1268,10 @@ impl Registration { target_perf: usize, capacity: usize, ) { - if let Ok(mut policy) = PolicyCpu::from_cpu(cpu) { + // SAFETY: The C API guarantees that `cpu` refers to a valid CPU number. + let cpu_id = unsafe { CpuId::from_u32_unchecked(cpu) }; + + if let Ok(mut policy) = PolicyCpu::from_cpu(cpu_id) { T::adjust_perf(&mut policy, min_perf, target_perf, capacity); } } @@ -1321,7 +1326,10 @@ impl Registration { /// /// - This function may only be called from the cpufreq C infrastructure. unsafe extern "C" fn get_callback(cpu: u32) -> kernel::ffi::c_uint { - PolicyCpu::from_cpu(cpu).map_or(0, |mut policy| T::get(&mut policy).map_or(0, |f| f)) + // SAFETY: The C API guarantees that `cpu` refers to a valid CPU number. + let cpu_id = unsafe { CpuId::from_u32_unchecked(cpu) }; + + PolicyCpu::from_cpu(cpu_id).map_or(0, |mut policy| T::get(&mut policy).map_or(0, |f| f)) } /// Driver's `update_limit` callback. @@ -1344,8 +1352,11 @@ impl Registration { /// - This function may only be called from the cpufreq C infrastructure. /// - The pointer arguments must be valid pointers. unsafe extern "C" fn bios_limit_callback(cpu: i32, limit: *mut u32) -> kernel::ffi::c_int { + // SAFETY: The C API guarantees that `cpu` refers to a valid CPU number. + let cpu_id = unsafe { CpuId::from_i32_unchecked(cpu) }; + from_result(|| { - let mut policy = PolicyCpu::from_cpu(cpu as u32)?; + let mut policy = PolicyCpu::from_cpu(cpu_id)?; // SAFETY: `limit` is guaranteed by the C code to be valid. T::bios_limit(&mut policy, &mut (unsafe { *limit })).map(|()| 0) -- cgit v1.2.3