Define Linux-style <preempt.h> interface.

Use it to disable sleeping in spinlock and rcu-read regions.

Signed-off-by: Keir Fraser <keir@xen.org>

1 files changed, 21 insertions, 33 deletions

diff --git a/xen/common/spinlock.c b/xen/common/spinlock.c
index fff796171d..2abf89e9b1 100644
--- a/xen/common/spinlock.c
+++ b/xen/common/spinlock.c
@@ -5,6 +5,7 @@
 #include <xen/time.h>
 #include <xen/spinlock.h>
 #include <xen/guest_access.h>
+#include <xen/preempt.h>
 #include <public/sysctl.h>
 #include <asm/processor.h>
 
@@ -39,22 +40,9 @@ void spin_debug_disable(void)
     atomic_dec(&spin_debug);
 }
 
-static DEFINE_PER_CPU(atomic_t, lockdepth);
-
-#define lockdepth_inc() atomic_inc(&this_cpu(lockdepth))
-#define lockdepth_dec() atomic_dec(&this_cpu(lockdepth))
-
-unsigned int locking_depth(void)
-{
-    return atomic_read(&this_cpu(lockdepth));
-}
-
 #else /* defined(NDEBUG) */
 
 #define check_lock(l) ((void)0)
-#define lockdepth_inc() ((void)0)
-#define lockdepth_dec() ((void)0)
-unsigned int locking_depth(void) { return 0; }
 
 #endif
 
@@ -94,7 +82,7 @@ void _spin_lock(spinlock_t *lock)
             cpu_relax();
     }
     LOCK_PROFILE_GOT;
-    lockdepth_inc();
+    preempt_disable();
 }
 
 void _spin_lock_irq(spinlock_t *lock)
@@ -113,7 +101,7 @@ void _spin_lock_irq(spinlock_t *lock)
         local_irq_disable();
     }
     LOCK_PROFILE_GOT;
-    lockdepth_inc();
+    preempt_disable();
 }
 
 unsigned long _spin_lock_irqsave(spinlock_t *lock)
@@ -132,20 +120,20 @@ unsigned long _spin_lock_irqsave(spinlock_t *lock)
         local_irq_save(flags);
     }
     LOCK_PROFILE_GOT;
-    lockdepth_inc();
+    preempt_disable();
     return flags;
 }
 
 void _spin_unlock(spinlock_t *lock)
 {
-    lockdepth_dec();
+    preempt_enable();
     LOCK_PROFILE_REL;
     _raw_spin_unlock(&lock->raw);
 }
 
 void _spin_unlock_irq(spinlock_t *lock)
 {
-    lockdepth_dec();
+    preempt_enable();
     LOCK_PROFILE_REL;
     _raw_spin_unlock(&lock->raw);
     local_irq_enable();
@@ -153,7 +141,7 @@ void _spin_unlock_irq(spinlock_t *lock)
 
 void _spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
 {
-    lockdepth_dec();
+    preempt_enable();
     LOCK_PROFILE_REL;
     _raw_spin_unlock(&lock->raw);
     local_irq_restore(flags);
@@ -173,7 +161,7 @@ int _spin_trylock(spinlock_t *lock)
 #ifdef LOCK_PROFILE
     lock->profile.time_locked = NOW();
 #endif
-    lockdepth_inc();
+    preempt_disable();
     return 1;
 }
 
@@ -247,7 +235,7 @@ void _read_lock(rwlock_t *lock)
 {
     check_lock(&lock->debug);
     _raw_read_lock(&lock->raw);
-    lockdepth_inc();
+    preempt_disable();
 }
 
 void _read_lock_irq(rwlock_t *lock)
@@ -256,7 +244,7 @@ void _read_lock_irq(rwlock_t *lock)
     local_irq_disable();
     check_lock(&lock->debug);
     _raw_read_lock(&lock->raw);
-    lockdepth_inc();
+    preempt_disable();
 }
 
 unsigned long _read_lock_irqsave(rwlock_t *lock)
@@ -265,26 +253,26 @@ unsigned long _read_lock_irqsave(rwlock_t *lock)
     local_irq_save(flags);
     check_lock(&lock->debug);
     _raw_read_lock(&lock->raw);
-    lockdepth_inc();
+    preempt_disable();
     return flags;
 }
 
 void _read_unlock(rwlock_t *lock)
 {
-    lockdepth_dec();
+    preempt_enable();
     _raw_read_unlock(&lock->raw);
 }
 
 void _read_unlock_irq(rwlock_t *lock)
 {
-    lockdepth_dec();
+    preempt_enable();
     _raw_read_unlock(&lock->raw);
     local_irq_enable();
 }
 
 void _read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 {
-    lockdepth_dec();
+    preempt_enable();
     _raw_read_unlock(&lock->raw);
     local_irq_restore(flags);
 }
@@ -293,7 +281,7 @@ void _write_lock(rwlock_t *lock)
 {
     check_lock(&lock->debug);
     _raw_write_lock(&lock->raw);
-    lockdepth_inc();
+    preempt_disable();
 }
 
 void _write_lock_irq(rwlock_t *lock)
@@ -302,7 +290,7 @@ void _write_lock_irq(rwlock_t *lock)
     local_irq_disable();
     check_lock(&lock->debug);
     _raw_write_lock(&lock->raw);
-    lockdepth_inc();
+    preempt_disable();
 }
 
 unsigned long _write_lock_irqsave(rwlock_t *lock)
@@ -311,7 +299,7 @@ unsigned long _write_lock_irqsave(rwlock_t *lock)
     local_irq_save(flags);
     check_lock(&lock->debug);
     _raw_write_lock(&lock->raw);
-    lockdepth_inc();
+    preempt_disable();
     return flags;
 }
 
@@ -320,26 +308,26 @@ int _write_trylock(rwlock_t *lock)
     check_lock(&lock->debug);
     if ( !_raw_write_trylock(&lock->raw) )
         return 0;
-    lockdepth_inc();
+    preempt_disable();
     return 1;
 }
 
 void _write_unlock(rwlock_t *lock)
 {
-    lockdepth_dec();
+    preempt_enable();
     _raw_write_unlock(&lock->raw);
 }
 
 void _write_unlock_irq(rwlock_t *lock)
 {
-    lockdepth_dec();
+    preempt_enable();
     _raw_write_unlock(&lock->raw);
     local_irq_enable();
 }
 
 void _write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 {
-    lockdepth_dec();
+    preempt_enable();
     _raw_write_unlock(&lock->raw);
     local_irq_restore(flags);
 }