fix: fix freeze upon closing Music app

kernel/src/Drivers/Audio/Mixer.cpp

@@ -327,10 +327,18 @@ namespace Drivers::Audio::Mixer {
         if (bitsPerSample != 16) return -1;
         if (sampleRate < 8000 || sampleRate > 192000) return -1;
 
+        // Allocate the input ring before taking g_lock. Walking the PFA free
+        // list for 16 contiguous pages and zeroing 64 KiB is long enough that
+        // doing it under the lock (with IRQs disabled) lets HDA BCIS IRQs
+        // spin on g_lock on other CPUs — the same hazard that wedged Close().
+        int16_t* ring = AllocRing();
+        if (!ring) return -1;
+
         g_lock.Acquire();
 
         if (!EnsureHdaOpen()) {
             g_lock.Release();
+            FreeRing(ring);
             return -1;
         }
 
@@ -340,16 +348,11 @@ namespace Drivers::Audio::Mixer {
         }
         if (slot < 0) {
             g_lock.Release();
+            FreeRing(ring);
             return -1;
         }
 
         VirtualStream& s = g_streams[slot];
-        int16_t* ring = AllocRing();
-        if (!ring) {
-            g_lock.Release();
-            return -1;
-        }
-
         s.active = true;
         s.ownerPid = ownerPid;
         int n = 0;