ftrace: user raw_spin_lock in tracing

Lock debugging enabled cause huge performance problems for tracing. Having
the lock verification happening for every function that is called
because mcount calls spin_lock can cripple the system.

This patch converts the spin_locks used by ftrace into raw_spin_locks.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 31 insertions, 22 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 736dcfb3ed01..3009aafa4dde 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -133,7 +133,8 @@ static const char *trace_options[] = {
         NULL
 };
 
-static DEFINE_SPINLOCK(ftrace_max_lock);
+static raw_spinlock_t ftrace_max_lock =
+        (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
 
 /*
  * Copy the new maximum trace into the separate maximum-trace
@@ -335,7 +336,7 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
         int i;
 
         WARN_ON_ONCE(!irqs_disabled());
-        spin_lock(&ftrace_max_lock);
+        __raw_spin_lock(&ftrace_max_lock);
         /* clear out all the previous traces */
         for_each_possible_cpu(i) {
                 data = tr->data[i];
@@ -344,7 +345,7 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
         }
 
         __update_max_tr(tr, tsk, cpu);
-        spin_unlock(&ftrace_max_lock);
+        __raw_spin_unlock(&ftrace_max_lock);
 }
 
 /**
@@ -360,7 +361,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
         int i;
 
         WARN_ON_ONCE(!irqs_disabled());
-        spin_lock(&ftrace_max_lock);
+        __raw_spin_lock(&ftrace_max_lock);
         for_each_possible_cpu(i)
                 tracing_reset(max_tr.data[i]);
 
@@ -368,7 +369,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
         tracing_reset(data);
 
         __update_max_tr(tr, tsk, cpu);
-        spin_unlock(&ftrace_max_lock);
+        __raw_spin_unlock(&ftrace_max_lock);
 }
 
 int register_tracer(struct tracer *type)
@@ -652,13 +653,15 @@ trace_function(struct trace_array *tr, struct trace_array_cpu *data,
         struct trace_entry *entry;
         unsigned long irq_flags;
 
-        spin_lock_irqsave(&data->lock, irq_flags);
+        raw_local_irq_save(irq_flags);
+        __raw_spin_lock(&data->lock);
         entry                   = tracing_get_trace_entry(tr, data);
         tracing_generic_entry_update(entry, flags);
         entry->type             = TRACE_FN;
         entry->fn.ip            = ip;
         entry->fn.parent_ip     = parent_ip;
-        spin_unlock_irqrestore(&data->lock, irq_flags);
+        __raw_spin_unlock(&data->lock);
+        raw_local_irq_restore(irq_flags);
 }
 
 void
@@ -678,14 +681,16 @@ __trace_special(void *__tr, void *__data,
         struct trace_entry *entry;
         unsigned long irq_flags;
 
-        spin_lock_irqsave(&data->lock, irq_flags);
+        raw_local_irq_save(irq_flags);
+        __raw_spin_lock(&data->lock);
         entry                   = tracing_get_trace_entry(tr, data);
         tracing_generic_entry_update(entry, 0);
         entry->type             = TRACE_SPECIAL;
         entry->special.arg1     = arg1;
         entry->special.arg2     = arg2;
         entry->special.arg3     = arg3;
-        spin_unlock_irqrestore(&data->lock, irq_flags);
+        __raw_spin_unlock(&data->lock);
+        raw_local_irq_restore(irq_flags);
 
         trace_wake_up();
 }
@@ -725,7 +730,8 @@ tracing_sched_switch_trace(struct trace_array *tr,
         struct trace_entry *entry;
         unsigned long irq_flags;
 
-        spin_lock_irqsave(&data->lock, irq_flags);
+        raw_local_irq_save(irq_flags);
+        __raw_spin_lock(&data->lock);
         entry                   = tracing_get_trace_entry(tr, data);
         tracing_generic_entry_update(entry, flags);
         entry->type             = TRACE_CTX;
@@ -736,7 +742,8 @@ tracing_sched_switch_trace(struct trace_array *tr,
         entry->ctx.next_prio    = next->prio;
         entry->ctx.next_state   = next->state;
         __trace_stack(tr, data, flags, 4);
-        spin_unlock_irqrestore(&data->lock, irq_flags);
+        __raw_spin_unlock(&data->lock);
+        raw_local_irq_restore(irq_flags);
 }
 
 void
@@ -749,7 +756,8 @@ tracing_sched_wakeup_trace(struct trace_array *tr,
         struct trace_entry *entry;
         unsigned long irq_flags;
 
-        spin_lock_irqsave(&data->lock, irq_flags);
+        raw_local_irq_save(irq_flags);
+        __raw_spin_lock(&data->lock);
         entry                   = tracing_get_trace_entry(tr, data);
         tracing_generic_entry_update(entry, flags);
         entry->type             = TRACE_WAKE;
@@ -760,7 +768,8 @@ tracing_sched_wakeup_trace(struct trace_array *tr,
         entry->ctx.next_prio    = wakee->prio;
         entry->ctx.next_state   = wakee->state;
         __trace_stack(tr, data, flags, 5);
-        spin_unlock_irqrestore(&data->lock, irq_flags);
+        __raw_spin_unlock(&data->lock);
+        raw_local_irq_restore(irq_flags);
 
         trace_wake_up();
 }
@@ -1824,7 +1833,8 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf,
         if (err)
                 goto err_unlock;
 
-        spin_lock_irq(&ftrace_max_lock);
+        raw_local_irq_disable();
+        __raw_spin_lock(&ftrace_max_lock);
         for_each_possible_cpu(cpu) {
                 /*
                  * Increase/decrease the disabled counter if we are
@@ -1839,7 +1849,8 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf,
                         atomic_dec(&global_trace.data[cpu]->disabled);
                 }
         }
-        spin_unlock_irq(&ftrace_max_lock);
+        __raw_spin_unlock(&ftrace_max_lock);
+        raw_local_irq_enable();
 
         tracing_cpumask = tracing_cpumask_new;
 
@@ -2299,7 +2310,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
 
         for_each_cpu_mask(cpu, mask) {
                 data = iter->tr->data[cpu];
-                spin_lock(&data->lock);
+                __raw_spin_lock(&data->lock);
         }
 
         while (find_next_entry_inc(iter) != NULL) {
@@ -2320,7 +2331,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
 
         for_each_cpu_mask(cpu, mask) {
                 data = iter->tr->data[cpu];
-                spin_unlock(&data->lock);
+                __raw_spin_unlock(&data->lock);
         }
 
         for_each_cpu_mask(cpu, mask) {
@@ -2538,8 +2549,7 @@ static int trace_alloc_page(void)
         /* Now that we successfully allocate a page per CPU, add them */
         for_each_possible_cpu(i) {
                 data = global_trace.data[i];
-                spin_lock_init(&data->lock);
-                lockdep_set_class(&data->lock, &data->lock_key);
+                data->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
                 page = list_entry(pages.next, struct page, lru);
                 list_del_init(&page->lru);
                 list_add_tail(&page->lru, &data->trace_pages);
@@ -2547,8 +2557,7 @@ static int trace_alloc_page(void)
 
 #ifdef CONFIG_TRACER_MAX_TRACE
                 data = max_tr.data[i];
-                spin_lock_init(&data->lock);
-                lockdep_set_class(&data->lock, &data->lock_key);
+                data->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
                 page = list_entry(pages.next, struct page, lru);
                 list_del_init(&page->lru);
                 list_add_tail(&page->lru, &data->trace_pages);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 98cbfd05d754..25cba28eb9ba 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -76,7 +76,7 @@ struct trace_entry {
 struct trace_array_cpu {
         struct list_head        trace_pages;
         atomic_t                disabled;
-        spinlock_t              lock;
+        raw_spinlock_t          lock;
         struct lock_class_key   lock_key;
 
         /* these fields get copied into max-trace: */