ring-buffer: convert to raw spinlocks
Impact: no lockdep debugging of ring buffer
The problem with running lockdep on the ring buffer is that the
ring buffer is the core infrastructure of ftrace. What happens is
that the tracer will start tracing the lockdep code while lockdep
is testing the ring buffers locks. This can cause lockdep to
fail due to testing cases that have not fully finished their
locking transition.
This patch converts the spin locks used by the ring buffer back
into raw spin locks which lockdep does not check.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 151f6a7..a2dea50 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -154,7 +154,7 @@
struct ring_buffer_per_cpu {
int cpu;
struct ring_buffer *buffer;
- spinlock_t lock;
+ raw_spinlock_t lock;
struct lock_class_key lock_key;
struct list_head pages;
struct buffer_page *head_page; /* read from head */
@@ -291,7 +291,7 @@
cpu_buffer->cpu = cpu;
cpu_buffer->buffer = buffer;
- spin_lock_init(&cpu_buffer->lock);
+ cpu_buffer->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
INIT_LIST_HEAD(&cpu_buffer->pages);
page = kzalloc_node(ALIGN(sizeof(*page), cache_line_size()),
@@ -854,7 +854,8 @@
if (write > BUF_PAGE_SIZE) {
struct buffer_page *next_page = tail_page;
- spin_lock_irqsave(&cpu_buffer->lock, flags);
+ local_irq_save(flags);
+ __raw_spin_lock(&cpu_buffer->lock);
rb_inc_page(cpu_buffer, &next_page);
@@ -930,7 +931,8 @@
rb_set_commit_to_write(cpu_buffer);
}
- spin_unlock_irqrestore(&cpu_buffer->lock, flags);
+ __raw_spin_unlock(&cpu_buffer->lock);
+ local_irq_restore(flags);
/* fail and let the caller try again */
return ERR_PTR(-EAGAIN);
@@ -953,7 +955,8 @@
return event;
out_unlock:
- spin_unlock_irqrestore(&cpu_buffer->lock, flags);
+ __raw_spin_unlock(&cpu_buffer->lock);
+ local_irq_restore(flags);
return NULL;
}
@@ -1524,7 +1527,8 @@
struct buffer_page *reader = NULL;
unsigned long flags;
- spin_lock_irqsave(&cpu_buffer->lock, flags);
+ local_irq_save(flags);
+ __raw_spin_lock(&cpu_buffer->lock);
again:
reader = cpu_buffer->reader_page;
@@ -1574,7 +1578,8 @@
goto again;
out:
- spin_unlock_irqrestore(&cpu_buffer->lock, flags);
+ __raw_spin_unlock(&cpu_buffer->lock);
+ local_irq_restore(flags);
return reader;
}
@@ -1815,9 +1820,11 @@
atomic_inc(&cpu_buffer->record_disabled);
synchronize_sched();
- spin_lock_irqsave(&cpu_buffer->lock, flags);
+ local_irq_save(flags);
+ __raw_spin_lock(&cpu_buffer->lock);
ring_buffer_iter_reset(iter);
- spin_unlock_irqrestore(&cpu_buffer->lock, flags);
+ __raw_spin_unlock(&cpu_buffer->lock);
+ local_irq_restore(flags);
return iter;
}
@@ -1903,11 +1910,13 @@
if (!cpu_isset(cpu, buffer->cpumask))
return;
- spin_lock_irqsave(&cpu_buffer->lock, flags);
+ local_irq_save(flags);
+ __raw_spin_lock(&cpu_buffer->lock);
rb_reset_cpu(cpu_buffer);
- spin_unlock_irqrestore(&cpu_buffer->lock, flags);
+ __raw_spin_unlock(&cpu_buffer->lock);
+ local_irq_restore(flags);
}
/**