fix(safety): resolve potential mutex deadlock in get_e_core_l2_cache_size

inureyes · inureyes · commit ed56f3ef6c95 · 2026-04-10T15:23:58.000+09:00
The original code acquired cached_s_core_count mutex twice in the same
if-expression. Rust drops temporaries at statement end, not at &amp;&amp;, so
when the first condition evaluated to true the second .lock() would
deadlock. Consolidate into a single lock acquisition with matches!.
diff --git a/src/device/cpu_macos.rs b/src/device/cpu_macos.rs
@@ -710,11 +710,12 @@ impl MacOsCpuReader {
     }
 
     fn get_e_core_l2_cache_size(&self) -> Result<u32, Box<dyn std::error::Error>> {
-        // M5 Pro/Max has no E-cores
-        if *self.cached_s_core_count.lock().unwrap() != Some(0)
-            && self.cached_s_core_count.lock().unwrap().is_some()
+        // M5 Pro/Max has no E-cores — skip if Super cores are present
         {
-            return Err("No E-cores on M5 Pro/Max".into());
+            let s_count = self.cached_s_core_count.lock().unwrap();
+            if matches!(*s_count, Some(n) if n > 0) {
+                return Err("No E-cores on M5 Pro/Max".into());
+            }
         }
 
         // Check if we have cached value

Original file line number	Diff line number	Diff line change
`@@ -710,11 +710,12 @@ impl MacOsCpuReader {`
`710`	`710`	`}`
`711`	`711`
`712`	`712`	`fn get_e_core_l2_cache_size(&self) -> Result<u32, Box<dyn std::error::Error>> {`
`713`		`- // M5 Pro/Max has no E-cores`
`714`		`- if *self.cached_s_core_count.lock().unwrap() != Some(0)`
`715`		`- && self.cached_s_core_count.lock().unwrap().is_some()`
	`713`	`+ // M5 Pro/Max has no E-cores — skip if Super cores are present`
`716`	`714`	`{`
`717`		`- return Err("No E-cores on M5 Pro/Max".into());`
	`715`	`+ let s_count = self.cached_s_core_count.lock().unwrap();`
	`716`	`+ if matches!(*s_count, Some(n) if n > 0) {`
	`717`	`+ return Err("No E-cores on M5 Pro/Max".into());`
	`718`	`+ }`
`718`	`719`	`}`
`719`	`720`
`720`	`721`	`// Check if we have cached value`