preempt_enable();
}
-int perf_output_begin(struct perf_output_handle *handle,
- struct perf_event *event, unsigned int size)
+static bool __always_inline
+ring_buffer_has_space(unsigned long head, unsigned long tail,
+ unsigned long data_size, unsigned int size,
+ bool backward)
+{
+ if (!backward)
+ return CIRC_SPACE(head, tail, data_size) >= size;
+ else
+ return CIRC_SPACE(tail, head, data_size) >= size;
+}
+
+static int __always_inline
+__perf_output_begin(struct perf_output_handle *handle,
+ struct perf_event *event, unsigned int size,
+ bool backward)
{
struct ring_buffer *rb;
unsigned long tail, offset, head;
if (unlikely(!rb))
goto out;
- if (unlikely(!rb->nr_pages))
+ if (unlikely(rb->paused)) {
+ if (rb->nr_pages)
+ local_inc(&rb->lost);
goto out;
+ }
handle->rb = rb;
handle->event = event;
do {
tail = READ_ONCE(rb->user_page->data_tail);
offset = head = local_read(&rb->head);
- if (!rb->overwrite &&
- unlikely(CIRC_SPACE(head, tail, perf_data_size(rb)) < size))
- goto fail;
+ if (!rb->overwrite) {
+ if (unlikely(!ring_buffer_has_space(head, tail,
+ perf_data_size(rb),
+ size, backward)))
+ goto fail;
+ }
/*
* The above forms a control dependency barrier separating the
* See perf_output_put_handle().
*/
- head += size;
+ if (!backward)
+ head += size;
+ else
+ head -= size;
} while (local_cmpxchg(&rb->head, offset, head) != offset);
+ if (backward) {
+ offset = head;
+ head = (u64)(-head);
+ }
+
/*
* We rely on the implied barrier() by local_cmpxchg() to ensure
* none of the data stores below can be lifted up by the compiler.
return -ENOSPC;
}
+int perf_output_begin_forward(struct perf_output_handle *handle,
+ struct perf_event *event, unsigned int size)
+{
+ return __perf_output_begin(handle, event, size, false);
+}
+
+int perf_output_begin_backward(struct perf_output_handle *handle,
+ struct perf_event *event, unsigned int size)
+{
+ return __perf_output_begin(handle, event, size, true);
+}
+
+int perf_output_begin(struct perf_output_handle *handle,
+ struct perf_event *event, unsigned int size)
+{
+
+ return __perf_output_begin(handle, event, size,
+ unlikely(is_write_backward(event)));
+}
+
unsigned int perf_output_copy(struct perf_output_handle *handle,
const void *buf, unsigned int len)
{
rcu_read_unlock();
}
-static void rb_irq_work(struct irq_work *work);
-
static void
ring_buffer_init(struct ring_buffer *rb, long watermark, int flags)
{
INIT_LIST_HEAD(&rb->event_list);
spin_lock_init(&rb->event_lock);
- init_irq_work(&rb->irq_work, rb_irq_work);
-}
-
-static void ring_buffer_put_async(struct ring_buffer *rb)
-{
- if (!atomic_dec_and_test(&rb->refcount))
- return;
- rb->rcu_head.next = (void *)rb;
- irq_work_queue(&rb->irq_work);
+ /*
+ * perf_output_begin() only checks rb->paused, therefore
+ * rb->paused must be true if we have no pages for output.
+ */
+ if (!rb->nr_pages)
+ rb->paused = 1;
}
/*
* The ordering is similar to that of perf_output_{begin,end}, with
* the exception of (B), which should be taken care of by the pmu
* driver, since ordering rules will differ depending on hardware.
+ *
+ * Call this from pmu::start(); see the comment in perf_aux_output_end()
+ * about its use in pmu callbacks. Both can also be called from the PMI
+ * handler if needed.
*/
void *perf_aux_output_begin(struct perf_output_handle *handle,
struct perf_event *event)
if (!rb)
return NULL;
- if (!rb_has_aux(rb) || !atomic_inc_not_zero(&rb->aux_refcount))
+ if (!rb_has_aux(rb))
+ goto err;
+
+ /*
+ * If aux_mmap_count is zero, the aux buffer is in perf_mmap_close(),
+ * about to get freed, so we leave immediately.
+ *
+ * Checking rb::aux_mmap_count and rb::refcount has to be done in
+ * the same order, see perf_mmap_close. Otherwise we end up freeing
+ * aux pages in this path, which is a bug, because in_atomic().
+ */
+ if (!atomic_read(&rb->aux_mmap_count))
+ goto err;
+
+ if (!atomic_inc_not_zero(&rb->aux_refcount))
goto err;
/*
return handle->rb->aux_priv;
err_put:
+ /* can't be last */
rb_free_aux(rb);
err:
- ring_buffer_put_async(rb);
+ ring_buffer_put(rb);
handle->event = NULL;
return NULL;
* aux_head and posting a PERF_RECORD_AUX into the perf buffer. It is the
* pmu driver's responsibility to observe ordering rules of the hardware,
* so that all the data is externally visible before this is called.
+ *
+ * Note: this has to be called from pmu::stop() callback, as the assumption
+ * of the AUX buffer management code is that after pmu::stop(), the AUX
+ * transaction must be stopped and therefore drop the AUX reference count.
*/
void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size,
bool truncated)
handle->event = NULL;
local_set(&rb->aux_nest, 0);
+ /* can't be last */
rb_free_aux(rb);
- ring_buffer_put_async(rb);
+ ring_buffer_put(rb);
}
/*
{
int pg;
+ /*
+ * Should never happen, the last reference should be dropped from
+ * perf_mmap_close() path, which first stops aux transactions (which
+ * in turn are the atomic holders of aux_refcount) and then does the
+ * last rb_free_aux().
+ */
+ WARN_ON_ONCE(in_atomic());
+
if (rb->aux_priv) {
rb->free_aux(rb->aux_priv);
rb->free_aux = NULL;
void rb_free_aux(struct ring_buffer *rb)
{
if (atomic_dec_and_test(&rb->aux_refcount))
- irq_work_queue(&rb->irq_work);
-}
-
-static void rb_irq_work(struct irq_work *work)
-{
- struct ring_buffer *rb = container_of(work, struct ring_buffer, irq_work);
-
- if (!atomic_read(&rb->aux_refcount))
__rb_free_aux(rb);
-
- if (rb->rcu_head.next == (void *)rb)
- call_rcu(&rb->rcu_head, rb_free_rcu);
}
#ifndef CONFIG_PERF_USE_VMALLOC
projects / cascardo / linux.git / blobdiff