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Diffstat (limited to 'kernel/trace/ring_buffer.c')
-rw-r--r--kernel/trace/ring_buffer.c151
1 files changed, 81 insertions, 70 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index f5b7b5c1195b..354017f455e5 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -478,7 +478,7 @@ struct ring_buffer_per_cpu {
int cpu;
atomic_t record_disabled;
struct ring_buffer *buffer;
- raw_spinlock_t reader_lock; /* serialize readers */
+ spinlock_t reader_lock; /* serialize readers */
arch_spinlock_t lock;
struct lock_class_key lock_key;
struct list_head *pages;
@@ -1049,6 +1049,44 @@ static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
return -ENOMEM;
}
+static inline int ok_to_lock(void)
+{
+ if (in_nmi())
+ return 0;
+#ifdef CONFIG_PREEMPT_RT_FULL
+ if (in_atomic())
+ return 0;
+#endif
+ return 1;
+}
+
+static int
+read_buffer_lock(struct ring_buffer_per_cpu *cpu_buffer,
+ unsigned long *flags)
+{
+ /*
+ * If an NMI die dumps out the content of the ring buffer
+ * do not grab locks. We also permanently disable the ring
+ * buffer too. A one time deal is all you get from reading
+ * the ring buffer from an NMI.
+ */
+ if (!ok_to_lock()) {
+ if (spin_trylock_irqsave(&cpu_buffer->reader_lock, *flags))
+ return 1;
+ tracing_off_permanent();
+ return 0;
+ }
+ spin_lock_irqsave(&cpu_buffer->reader_lock, *flags);
+ return 1;
+}
+
+static void
+read_buffer_unlock(struct ring_buffer_per_cpu *cpu_buffer,
+ unsigned long flags, int locked)
+{
+ if (locked)
+ spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+}
static struct ring_buffer_per_cpu *
rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu)
{
@@ -1064,7 +1102,7 @@ rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu)
cpu_buffer->cpu = cpu;
cpu_buffer->buffer = buffer;
- raw_spin_lock_init(&cpu_buffer->reader_lock);
+ spin_lock_init(&cpu_buffer->reader_lock);
lockdep_set_class(&cpu_buffer->reader_lock, buffer->reader_lock_key);
cpu_buffer->lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
@@ -1259,9 +1297,11 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages)
{
struct buffer_page *bpage;
struct list_head *p;
+ unsigned long flags;
unsigned i;
+ int locked;
- raw_spin_lock_irq(&cpu_buffer->reader_lock);
+ locked = read_buffer_lock(cpu_buffer, &flags);
rb_head_page_deactivate(cpu_buffer);
for (i = 0; i < nr_pages; i++) {
@@ -1279,7 +1319,7 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages)
rb_check_pages(cpu_buffer);
out:
- raw_spin_unlock_irq(&cpu_buffer->reader_lock);
+ read_buffer_unlock(cpu_buffer, flags, locked);
}
static void
@@ -1288,9 +1328,11 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer,
{
struct buffer_page *bpage;
struct list_head *p;
+ unsigned long flags;
unsigned i;
+ int locked;
- raw_spin_lock_irq(&cpu_buffer->reader_lock);
+ locked = read_buffer_lock(cpu_buffer, &flags);
rb_head_page_deactivate(cpu_buffer);
for (i = 0; i < nr_pages; i++) {
@@ -1305,7 +1347,7 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer,
rb_check_pages(cpu_buffer);
out:
- raw_spin_unlock_irq(&cpu_buffer->reader_lock);
+ read_buffer_unlock(cpu_buffer, flags, locked);
}
/**
@@ -2689,7 +2731,7 @@ unsigned long ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu)
return 0;
cpu_buffer = buffer->buffers[cpu];
- raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+ spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
/*
* if the tail is on reader_page, oldest time stamp is on the reader
* page
@@ -2699,7 +2741,7 @@ unsigned long ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu)
else
bpage = rb_set_head_page(cpu_buffer);
ret = bpage->page->time_stamp;
- raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+ spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
return ret;
}
@@ -2863,15 +2905,16 @@ void ring_buffer_iter_reset(struct ring_buffer_iter *iter)
{
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long flags;
+ int locked;
if (!iter)
return;
cpu_buffer = iter->cpu_buffer;
- raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+ locked = read_buffer_lock(cpu_buffer, &flags);
rb_iter_reset(iter);
- raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+ read_buffer_unlock(cpu_buffer, flags, locked);
}
EXPORT_SYMBOL_GPL(ring_buffer_iter_reset);
@@ -3289,21 +3332,6 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
}
EXPORT_SYMBOL_GPL(ring_buffer_iter_peek);
-static inline int rb_ok_to_lock(void)
-{
- /*
- * If an NMI die dumps out the content of the ring buffer
- * do not grab locks. We also permanently disable the ring
- * buffer too. A one time deal is all you get from reading
- * the ring buffer from an NMI.
- */
- if (likely(!in_nmi()))
- return 1;
-
- tracing_off_permanent();
- return 0;
-}
-
/**
* ring_buffer_peek - peek at the next event to be read
* @buffer: The ring buffer to read
@@ -3321,22 +3349,17 @@ ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts,
struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
struct ring_buffer_event *event;
unsigned long flags;
- int dolock;
+ int locked;
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return NULL;
- dolock = rb_ok_to_lock();
again:
- local_irq_save(flags);
- if (dolock)
- raw_spin_lock(&cpu_buffer->reader_lock);
+ locked = read_buffer_lock(cpu_buffer, &flags);
event = rb_buffer_peek(cpu_buffer, ts, lost_events);
if (event && event->type_len == RINGBUF_TYPE_PADDING)
rb_advance_reader(cpu_buffer);
- if (dolock)
- raw_spin_unlock(&cpu_buffer->reader_lock);
- local_irq_restore(flags);
+ read_buffer_unlock(cpu_buffer, flags, locked);
if (event && event->type_len == RINGBUF_TYPE_PADDING)
goto again;
@@ -3358,11 +3381,12 @@ ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer;
struct ring_buffer_event *event;
unsigned long flags;
+ int locked;
again:
- raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+ locked = read_buffer_lock(cpu_buffer, &flags);
event = rb_iter_peek(iter, ts);
- raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+ read_buffer_unlock(cpu_buffer, flags, locked);
if (event && event->type_len == RINGBUF_TYPE_PADDING)
goto again;
@@ -3388,9 +3412,7 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts,
struct ring_buffer_per_cpu *cpu_buffer;
struct ring_buffer_event *event = NULL;
unsigned long flags;
- int dolock;
-
- dolock = rb_ok_to_lock();
+ int locked;
again:
/* might be called in atomic */
@@ -3400,9 +3422,7 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts,
goto out;
cpu_buffer = buffer->buffers[cpu];
- local_irq_save(flags);
- if (dolock)
- raw_spin_lock(&cpu_buffer->reader_lock);
+ locked = read_buffer_lock(cpu_buffer, &flags);
event = rb_buffer_peek(cpu_buffer, ts, lost_events);
if (event) {
@@ -3410,9 +3430,8 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts,
rb_advance_reader(cpu_buffer);
}
- if (dolock)
- raw_spin_unlock(&cpu_buffer->reader_lock);
- local_irq_restore(flags);
+ read_buffer_unlock(cpu_buffer, flags, locked);
+
out:
preempt_enable();
@@ -3497,17 +3516,18 @@ ring_buffer_read_start(struct ring_buffer_iter *iter)
{
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long flags;
+ int locked;
if (!iter)
return;
cpu_buffer = iter->cpu_buffer;
- raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+ locked = read_buffer_lock(cpu_buffer, &flags);
arch_spin_lock(&cpu_buffer->lock);
rb_iter_reset(iter);
arch_spin_unlock(&cpu_buffer->lock);
- raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+ read_buffer_unlock(cpu_buffer, flags, locked);
}
EXPORT_SYMBOL_GPL(ring_buffer_read_start);
@@ -3541,8 +3561,9 @@ ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts)
struct ring_buffer_event *event;
struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer;
unsigned long flags;
+ int locked;
- raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+ locked = read_buffer_lock(cpu_buffer, &flags);
again:
event = rb_iter_peek(iter, ts);
if (!event)
@@ -3553,7 +3574,7 @@ ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts)
rb_advance_iter(iter);
out:
- raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+ read_buffer_unlock(cpu_buffer, flags, locked);
return event;
}
@@ -3618,13 +3639,14 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
unsigned long flags;
+ int locked;
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return;
atomic_inc(&cpu_buffer->record_disabled);
- raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+ locked = read_buffer_lock(cpu_buffer, &flags);
if (RB_WARN_ON(cpu_buffer, local_read(&cpu_buffer->committing)))
goto out;
@@ -3636,7 +3658,7 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu)
arch_spin_unlock(&cpu_buffer->lock);
out:
- raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+ read_buffer_unlock(cpu_buffer, flags, locked);
atomic_dec(&cpu_buffer->record_disabled);
}
@@ -3663,22 +3685,16 @@ int ring_buffer_empty(struct ring_buffer *buffer)
{
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long flags;
- int dolock;
+ int locked;
int cpu;
int ret;
- dolock = rb_ok_to_lock();
-
/* yes this is racy, but if you don't like the race, lock the buffer */
for_each_buffer_cpu(buffer, cpu) {
cpu_buffer = buffer->buffers[cpu];
- local_irq_save(flags);
- if (dolock)
- raw_spin_lock(&cpu_buffer->reader_lock);
+ locked = read_buffer_lock(cpu_buffer, &flags);
ret = rb_per_cpu_empty(cpu_buffer);
- if (dolock)
- raw_spin_unlock(&cpu_buffer->reader_lock);
- local_irq_restore(flags);
+ read_buffer_unlock(cpu_buffer, flags, locked);
if (!ret)
return 0;
@@ -3697,22 +3713,16 @@ int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long flags;
- int dolock;
+ int locked;
int ret;
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return 1;
- dolock = rb_ok_to_lock();
-
cpu_buffer = buffer->buffers[cpu];
- local_irq_save(flags);
- if (dolock)
- raw_spin_lock(&cpu_buffer->reader_lock);
+ locked = read_buffer_lock(cpu_buffer, &flags);
ret = rb_per_cpu_empty(cpu_buffer);
- if (dolock)
- raw_spin_unlock(&cpu_buffer->reader_lock);
- local_irq_restore(flags);
+ read_buffer_unlock(cpu_buffer, flags, locked);
return ret;
}
@@ -3887,6 +3897,7 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
unsigned int commit;
unsigned int read;
u64 save_timestamp;
+ int locked;
int ret = -1;
if (!cpumask_test_cpu(cpu, buffer->cpumask))
@@ -3908,7 +3919,7 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
if (!bpage)
goto out;
- raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+ locked = read_buffer_lock(cpu_buffer, &flags);
reader = rb_get_reader_page(cpu_buffer);
if (!reader)
@@ -4032,7 +4043,7 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
memset(&bpage->data[commit], 0, BUF_PAGE_SIZE - commit);
out_unlock:
- raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+ read_buffer_unlock(cpu_buffer, flags, locked);
out:
return ret;
generated by cgit v1.2.3 (git 2.0.4) at 2024-11-11 18:06:57 +0000