Kernel: Change kmalloc lock to be recursive

If the heap code dumps a stack trace (e.g. out of memory) then it may recursively call into it. Rather than deadlocking, allow recursion.
akimdi · Jul 3, 2020 · 3cc0e86 · 3cc0e86
1 parent 038dd9f
commit 3cc0e86
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diff --git a/Kernel/Heap/kmalloc.cpp b/Kernel/Heap/kmalloc.cpp
@@ -67,7 +67,7 @@ bool g_dump_kmalloc_stacks;
 static u8* s_next_eternal_ptr;
 static u8* s_end_of_eternal_range;
 
-static SpinLock s_lock;
+static RecursiveSpinLock s_lock; // needs to be recursive because of dump_backtrace()
 
 void kmalloc_init()
 {

diff --git a/Kernel/SpinLock.h b/Kernel/SpinLock.h
@@ -103,6 +103,11 @@ class RecursiveSpinLock
  {
  return m_lock.load(AK::memory_order_consume) != 0;
  }
+
+ ALWAYS_INLINE void initialize()
+ {
+ m_lock.store(0, AK::memory_order_release);
+ }
 };
 
 template <typename BaseType = u32, typename LockType = SpinLock<BaseType>>