spinlock: Add debug-build checks for IRQ-safe spinlocks.

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/xen/common/spinlock.c b/xen/common/spinlock.c
index 438e51deb8..95affbde01 100644
--- a/xen/common/spinlock.c
+++ b/xen/common/spinlock.c
@@ -1,9 +1,48 @@
 #include <xen/config.h>
+#include <xen/irq.h>
 #include <xen/smp.h>
 #include <xen/spinlock.h>
 
+#ifndef NDEBUG
+
+static atomic_t spin_debug __read_mostly = ATOMIC_INIT(0);
+
+static void check_lock(struct lock_debug *debug)
+{
+    int irq_safe = !local_irq_is_enabled();
+
+    if ( unlikely(atomic_read(&spin_debug) <= 0) )
+        return;
+
+    /* A few places take liberties with this. */
+    /* BUG_ON(in_irq() && !irq_safe); */
+
+    if ( unlikely(debug->irq_safe != irq_safe) )
+    {
+        int seen = cmpxchg(&debug->irq_safe, -1, irq_safe);
+        BUG_ON(seen == !irq_safe);
+    }
+}
+
+void spin_debug_enable(void)
+{
+    atomic_inc(&spin_debug);
+}
+
+void spin_debug_disable(void)
+{
+    atomic_dec(&spin_debug);
+}
+
+#else /* defined(NDEBUG) */
+
+#define check_lock(l) ((void)0)
+
+#endif
+
 void _spin_lock(spinlock_t *lock)
 {
+    check_lock(&lock->debug);
     _raw_spin_lock(&lock->raw);
 }
 
@@ -11,6 +50,7 @@ void _spin_lock_irq(spinlock_t *lock)
 {
     ASSERT(local_irq_is_enabled());
     local_irq_disable();
+    check_lock(&lock->debug);
     _raw_spin_lock(&lock->raw);
 }
 
@@ -18,6 +58,7 @@ unsigned long _spin_lock_irqsave(spinlock_t *lock)
 {
     unsigned long flags;
     local_irq_save(flags);
+    check_lock(&lock->debug);
     _raw_spin_lock(&lock->raw);
     return flags;
 }
@@ -41,16 +82,19 @@ void _spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
 
 int _spin_is_locked(spinlock_t *lock)
 {
+    check_lock(&lock->debug);
     return _raw_spin_is_locked(&lock->raw);
 }
 
 int _spin_trylock(spinlock_t *lock)
 {
+    check_lock(&lock->debug);
     return _raw_spin_trylock(&lock->raw);
 }
 
 void _spin_barrier(spinlock_t *lock)
 {
+    check_lock(&lock->debug);
     do { mb(); } while ( _raw_spin_is_locked(&lock->raw) );
     mb();
 }
@@ -70,6 +114,8 @@ void _spin_lock_recursive(spinlock_t *lock)
     /* Don't allow overflow of recurse_cpu field. */
     BUILD_BUG_ON(NR_CPUS > 0xfffu);
 
+    check_lock(&lock->debug);
+
     if ( likely(lock->recurse_cpu != cpu) )
     {
         spin_lock(lock);
@@ -92,6 +138,7 @@ void _spin_unlock_recursive(spinlock_t *lock)
 
 void _read_lock(rwlock_t *lock)
 {
+    check_lock(&lock->debug);
     _raw_read_lock(&lock->raw);
 }
 
@@ -99,6 +146,7 @@ void _read_lock_irq(rwlock_t *lock)
 {
     ASSERT(local_irq_is_enabled());
     local_irq_disable();
+    check_lock(&lock->debug);
     _raw_read_lock(&lock->raw);
 }
 
@@ -106,6 +154,7 @@ unsigned long _read_lock_irqsave(rwlock_t *lock)
 {
     unsigned long flags;
     local_irq_save(flags);
+    check_lock(&lock->debug);
     _raw_read_lock(&lock->raw);
     return flags;
 }
@@ -129,6 +178,7 @@ void _read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 
 void _write_lock(rwlock_t *lock)
 {
+    check_lock(&lock->debug);
     _raw_write_lock(&lock->raw);
 }
 
@@ -136,6 +186,7 @@ void _write_lock_irq(rwlock_t *lock)
 {
     ASSERT(local_irq_is_enabled());
     local_irq_disable();
+    check_lock(&lock->debug);
     _raw_write_lock(&lock->raw);
 }
 
@@ -143,6 +194,7 @@ unsigned long _write_lock_irqsave(rwlock_t *lock)
 {
     unsigned long flags;
     local_irq_save(flags);
+    check_lock(&lock->debug);
     _raw_write_lock(&lock->raw);
     return flags;
 }