4 files changed, 259 insertions, 5 deletions

diff --git a/lib/Makefile b/lib/Makefile
index d9c38ba05e7b..44a46750690a 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -16,6 +16,7 @@ CFLAGS_kobject.o += -DDEBUG
 CFLAGS_kobject_uevent.o += -DDEBUG
 endif
 
+obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o
 lib-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o
 lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
 lib-$(CONFIG_SEMAPHORE_SLEEPERS) += semaphore-sleepers.o
diff --git a/lib/dec_and_lock.c b/lib/dec_and_lock.c
index 6658d81e1836..2377af057d09 100644
--- a/lib/dec_and_lock.c
+++ b/lib/dec_and_lock.c
@@ -25,8 +25,6 @@
  * this is trivially done efficiently using a load-locked
  * store-conditional approach, for example.
  */
-
-#ifndef ATOMIC_DEC_AND_LOCK
 int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
 {
         spin_lock(lock);
@@ -37,4 +35,3 @@ int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
 }
 
 EXPORT_SYMBOL(_atomic_dec_and_lock);
-#endif
diff --git a/lib/kernel_lock.c b/lib/kernel_lock.c
index bd2bc5d887b8..cb5490ec00f2 100644
--- a/lib/kernel_lock.c
+++ b/lib/kernel_lock.c
@@ -177,8 +177,7 @@ static inline void __lock_kernel(void)
 
 static inline void __unlock_kernel(void)
 {
-        _raw_spin_unlock(&kernel_flag);
-        preempt_enable();
+        spin_unlock(&kernel_flag);
 }
 
 /*
diff --git a/lib/spinlock_debug.c b/lib/spinlock_debug.c
new file mode 100644
index 000000000000..906ad101eab3
--- /dev/null
+++ b/lib/spinlock_debug.c
@@ -0,0 +1,257 @@
+/*
+ * Copyright 2005, Red Hat, Inc., Ingo Molnar
+ * Released under the General Public License (GPL).
+ *
+ * This file contains the spinlock/rwlock implementations for
+ * DEBUG_SPINLOCK.
+ */
+
+#include <linux/config.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+
+static void spin_bug(spinlock_t *lock, const char *msg)
+{
+        static long print_once = 1;
+        struct task_struct *owner = NULL;
+
+        if (xchg(&print_once, 0)) {
+                if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT)
+                        owner = lock->owner;
+                printk("BUG: spinlock %s on CPU#%d, %s/%d\n",
+                        msg, smp_processor_id(), current->comm, current->pid);
+                printk(" lock: %p, .magic: %08x, .owner: %s/%d, .owner_cpu: %d\n",
+                        lock, lock->magic,
+                        owner ? owner->comm : "<none>",
+                        owner ? owner->pid : -1,
+                        lock->owner_cpu);
+                dump_stack();
+#ifdef CONFIG_SMP
+                /*
+                 * We cannot continue on SMP:
+                 */
+//              panic("bad locking");
+#endif
+        }
+}
+
+#define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
+
+static inline void debug_spin_lock_before(spinlock_t *lock)
+{
+        SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
+        SPIN_BUG_ON(lock->owner == current, lock, "recursion");
+        SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
+                                                        lock, "cpu recursion");
+}
+
+static inline void debug_spin_lock_after(spinlock_t *lock)
+{
+        lock->owner_cpu = raw_smp_processor_id();
+        lock->owner = current;
+}
+
+static inline void debug_spin_unlock(spinlock_t *lock)
+{
+        SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
+        SPIN_BUG_ON(!spin_is_locked(lock), lock, "already unlocked");
+        SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
+        SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
+                                                        lock, "wrong CPU");
+        lock->owner = SPINLOCK_OWNER_INIT;
+        lock->owner_cpu = -1;
+}
+
+static void __spin_lock_debug(spinlock_t *lock)
+{
+        int print_once = 1;
+        u64 i;
+
+        for (;;) {
+                for (i = 0; i < loops_per_jiffy * HZ; i++) {
+                        cpu_relax();
+                        if (__raw_spin_trylock(&lock->raw_lock))
+                                return;
+                }
+                /* lockup suspected: */
+                if (print_once) {
+                        print_once = 0;
+                        printk("BUG: spinlock lockup on CPU#%d, %s/%d, %p\n",
+                                smp_processor_id(), current->comm, current->pid,
+                                        lock);
+                        dump_stack();
+                }
+        }
+}
+
+void _raw_spin_lock(spinlock_t *lock)
+{
+        debug_spin_lock_before(lock);
+        if (unlikely(!__raw_spin_trylock(&lock->raw_lock)))
+                __spin_lock_debug(lock);
+        debug_spin_lock_after(lock);
+}
+
+int _raw_spin_trylock(spinlock_t *lock)
+{
+        int ret = __raw_spin_trylock(&lock->raw_lock);
+
+        if (ret)
+                debug_spin_lock_after(lock);
+#ifndef CONFIG_SMP
+        /*
+         * Must not happen on UP:
+         */
+        SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
+#endif
+        return ret;
+}
+
+void _raw_spin_unlock(spinlock_t *lock)
+{
+        debug_spin_unlock(lock);
+        __raw_spin_unlock(&lock->raw_lock);
+}
+
+static void rwlock_bug(rwlock_t *lock, const char *msg)
+{
+        static long print_once = 1;
+
+        if (xchg(&print_once, 0)) {
+                printk("BUG: rwlock %s on CPU#%d, %s/%d, %p\n", msg,
+                        smp_processor_id(), current->comm, current->pid, lock);
+                dump_stack();
+#ifdef CONFIG_SMP
+                /*
+                 * We cannot continue on SMP:
+                 */
+                panic("bad locking");
+#endif
+        }
+}
+
+#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
+
+static void __read_lock_debug(rwlock_t *lock)
+{
+        int print_once = 1;
+        u64 i;
+
+        for (;;) {
+                for (i = 0; i < loops_per_jiffy * HZ; i++) {
+                        cpu_relax();
+                        if (__raw_read_trylock(&lock->raw_lock))
+                                return;
+                }
+                /* lockup suspected: */
+                if (print_once) {
+                        print_once = 0;
+                        printk("BUG: read-lock lockup on CPU#%d, %s/%d, %p\n",
+                                smp_processor_id(), current->comm, current->pid,
+                                        lock);
+                        dump_stack();
+                }
+        }
+}
+
+void _raw_read_lock(rwlock_t *lock)
+{
+        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+        if (unlikely(!__raw_read_trylock(&lock->raw_lock)))
+                __read_lock_debug(lock);
+}
+
+int _raw_read_trylock(rwlock_t *lock)
+{
+        int ret = __raw_read_trylock(&lock->raw_lock);
+
+#ifndef CONFIG_SMP
+        /*
+         * Must not happen on UP:
+         */
+        RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
+#endif
+        return ret;
+}
+
+void _raw_read_unlock(rwlock_t *lock)
+{
+        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+        __raw_read_unlock(&lock->raw_lock);
+}
+
+static inline void debug_write_lock_before(rwlock_t *lock)
+{
+        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+        RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
+        RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
+                                                        lock, "cpu recursion");
+}
+
+static inline void debug_write_lock_after(rwlock_t *lock)
+{
+        lock->owner_cpu = raw_smp_processor_id();
+        lock->owner = current;
+}
+
+static inline void debug_write_unlock(rwlock_t *lock)
+{
+        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
+        RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
+        RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
+                                                        lock, "wrong CPU");
+        lock->owner = SPINLOCK_OWNER_INIT;
+        lock->owner_cpu = -1;
+}
+
+static void __write_lock_debug(rwlock_t *lock)
+{
+        int print_once = 1;
+        u64 i;
+
+        for (;;) {
+                for (i = 0; i < loops_per_jiffy * HZ; i++) {
+                        cpu_relax();
+                        if (__raw_write_trylock(&lock->raw_lock))
+                                return;
+                }
+                /* lockup suspected: */
+                if (print_once) {
+                        print_once = 0;
+                        printk("BUG: write-lock lockup on CPU#%d, %s/%d, %p\n",
+                                smp_processor_id(), current->comm, current->pid,
+                                        lock);
+                        dump_stack();
+                }
+        }
+}
+
+void _raw_write_lock(rwlock_t *lock)
+{
+        debug_write_lock_before(lock);
+        if (unlikely(!__raw_write_trylock(&lock->raw_lock)))
+                __write_lock_debug(lock);
+        debug_write_lock_after(lock);
+}
+
+int _raw_write_trylock(rwlock_t *lock)
+{
+        int ret = __raw_write_trylock(&lock->raw_lock);
+
+        if (ret)
+                debug_write_lock_after(lock);
+#ifndef CONFIG_SMP
+        /*
+         * Must not happen on UP:
+         */
+        RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
+#endif
+        return ret;
+}
+
+void _raw_write_unlock(rwlock_t *lock)
+{
+        debug_write_unlock(lock);
+        __raw_write_unlock(&lock->raw_lock);
+}