* lib/kernel_lock.c
*
* This is the traditional BKL - big kernel lock. Largely
- * relegated to obsolescense, but used by various less
+ * relegated to obsolescence, but used by various less
* important (or lazy) subsystems.
*/
-#include <linux/smp_lock.h>
#include <linux/module.h>
#include <linux/kallsyms.h>
+#include <linux/semaphore.h>
+#include <linux/smp_lock.h>
-#if defined(CONFIG_PREEMPT) && defined(__smp_processor_id) && \
- defined(CONFIG_DEBUG_PREEMPT)
-
-/*
- * Debugging check.
- */
-unsigned int smp_processor_id(void)
-{
- unsigned long preempt_count = preempt_count();
- int this_cpu = __smp_processor_id();
- cpumask_t this_mask;
-
- if (likely(preempt_count))
- goto out;
-
- if (irqs_disabled())
- goto out;
-
- /*
- * Kernel threads bound to a single CPU can safely use
- * smp_processor_id():
- */
- this_mask = cpumask_of_cpu(this_cpu);
-
- if (cpus_equal(current->cpus_allowed, this_mask))
- goto out;
-
- /*
- * It is valid to assume CPU-locality during early bootup:
- */
- if (system_state != SYSTEM_RUNNING)
- goto out;
-
- /*
- * Avoid recursion:
- */
- preempt_disable();
-
- if (!printk_ratelimit())
- goto out_enable;
-
- printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] code: %s/%d\n", preempt_count(), current->comm, current->pid);
- print_symbol("caller is %s\n", (long)__builtin_return_address(0));
- dump_stack();
-
-out_enable:
- preempt_enable_no_resched();
-out:
- return this_cpu;
-}
-
-EXPORT_SYMBOL(smp_processor_id);
-
-#endif /* PREEMPT && __smp_processor_id && DEBUG_PREEMPT */
-
-#ifdef CONFIG_PREEMPT_BKL
-/*
- * The 'big kernel semaphore'
- *
- * This mutex is taken and released recursively by lock_kernel()
- * and unlock_kernel(). It is transparently dropped and reaquired
- * over schedule(). It is used to protect legacy code that hasn't
- * been migrated to a proper locking design yet.
- *
- * Note: code locked by this semaphore will only be serialized against
- * other code using the same locking facility. The code guarantees that
- * the task remains on the same CPU.
- *
- * Don't use in new code.
- */
-static DECLARE_MUTEX(kernel_sem);
-
-/*
- * Re-acquire the kernel semaphore.
- *
- * This function is called with preemption off.
- *
- * We are executing in schedule() so the code must be extremely careful
- * about recursion, both due to the down() and due to the enabling of
- * preemption. schedule() will re-check the preemption flag after
- * reacquiring the semaphore.
- */
-int __lockfunc __reacquire_kernel_lock(void)
-{
- struct task_struct *task = current;
- int saved_lock_depth = task->lock_depth;
-
- BUG_ON(saved_lock_depth < 0);
-
- task->lock_depth = -1;
- preempt_enable_no_resched();
-
- down(&kernel_sem);
-
- preempt_disable();
- task->lock_depth = saved_lock_depth;
-
- return 0;
-}
-
-void __lockfunc __release_kernel_lock(void)
-{
- up(&kernel_sem);
-}
-
-/*
- * Getting the big kernel semaphore.
- */
-void __lockfunc lock_kernel(void)
-{
- struct task_struct *task = current;
- int depth = task->lock_depth + 1;
-
- if (likely(!depth))
- /*
- * No recursion worries - we set up lock_depth _after_
- */
- down(&kernel_sem);
-
- task->lock_depth = depth;
-}
-
-void __lockfunc unlock_kernel(void)
-{
- struct task_struct *task = current;
-
- BUG_ON(task->lock_depth < 0);
-
- if (likely(--task->lock_depth < 0))
- up(&kernel_sem);
-}
-
-#else
+#define CREATE_TRACE_POINTS
+#include <trace/events/bkl.h>
/*
* The 'big kernel lock'
*
* This spinlock is taken and released recursively by lock_kernel()
- * and unlock_kernel(). It is transparently dropped and reaquired
+ * and unlock_kernel(). It is transparently dropped and reacquired
* over schedule(). It is used to protect legacy code that hasn't
* been migrated to a proper locking design yet.
*
* Don't use in new code.
*/
-static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kernel_flag);
+static __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(kernel_flag);
/*
* If it successfully gets the lock, it should increment
* the preemption count like any spinlock does.
*
- * (This works on UP too - _raw_spin_trylock will never
+ * (This works on UP too - do_raw_spin_trylock will never
* return false in that case)
*/
int __lockfunc __reacquire_kernel_lock(void)
{
- while (!_raw_spin_trylock(&kernel_flag)) {
- if (test_thread_flag(TIF_NEED_RESCHED))
+ while (!do_raw_spin_trylock(&kernel_flag)) {
+ if (need_resched())
return -EAGAIN;
cpu_relax();
}
void __lockfunc __release_kernel_lock(void)
{
- _raw_spin_unlock(&kernel_flag);
+ do_raw_spin_unlock(&kernel_flag);
preempt_enable_no_resched();
}
/*
- * These are the BKL spinlocks - we try to be polite about preemption.
+ * These are the BKL spinlocks - we try to be polite about preemption.
* If SMP is not on (ie UP preemption), this all goes away because the
- * _raw_spin_trylock() will always succeed.
+ * do_raw_spin_trylock() will always succeed.
*/
#ifdef CONFIG_PREEMPT
static inline void __lock_kernel(void)
{
preempt_disable();
- if (unlikely(!_raw_spin_trylock(&kernel_flag))) {
+ if (unlikely(!do_raw_spin_trylock(&kernel_flag))) {
/*
* If preemption was disabled even before this
* was called, there's nothing we can be polite
* about - just spin.
*/
if (preempt_count() > 1) {
- _raw_spin_lock(&kernel_flag);
+ do_raw_spin_lock(&kernel_flag);
return;
}
*/
do {
preempt_enable();
- while (spin_is_locked(&kernel_flag))
+ while (raw_spin_is_locked(&kernel_flag))
cpu_relax();
preempt_disable();
- } while (!_raw_spin_trylock(&kernel_flag));
+ } while (!do_raw_spin_trylock(&kernel_flag));
}
}
*/
static inline void __lock_kernel(void)
{
- _raw_spin_lock(&kernel_flag);
+ do_raw_spin_lock(&kernel_flag);
}
#endif
static inline void __unlock_kernel(void)
{
- _raw_spin_unlock(&kernel_flag);
+ /*
+ * the BKL is not covered by lockdep, so we open-code the
+ * unlocking sequence (and thus avoid the dep-chain ops):
+ */
+ do_raw_spin_unlock(&kernel_flag);
preempt_enable();
}
* This cannot happen asynchronously, so we only need to
* worry about other CPU's.
*/
-void __lockfunc lock_kernel(void)
+void __lockfunc _lock_kernel(const char *func, const char *file, int line)
{
- int depth = current->lock_depth+1;
- if (likely(!depth))
+ int depth = current->lock_depth + 1;
+
+ trace_lock_kernel(func, file, line);
+
+ if (likely(!depth)) {
+ might_sleep();
__lock_kernel();
+ }
current->lock_depth = depth;
}
-void __lockfunc unlock_kernel(void)
+void __lockfunc _unlock_kernel(const char *func, const char *file, int line)
{
BUG_ON(current->lock_depth < 0);
if (likely(--current->lock_depth < 0))
__unlock_kernel();
-}
-#endif
+ trace_unlock_kernel(func, file, line);
+}
-EXPORT_SYMBOL(lock_kernel);
-EXPORT_SYMBOL(unlock_kernel);
+EXPORT_SYMBOL(_lock_kernel);
+EXPORT_SYMBOL(_unlock_kernel);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff