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Subject[PATCH 10/15] perf_counter: small cleanup of the output routines
Move the nmi argument to the _begin() function, so that _end() only needs the
handle. This allows the _begin() function to generate a wakeup on event loss.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
kernel/perf_counter.c | 42 ++++++++++++++++++++++++++----------------
1 file changed, 26 insertions(+), 16 deletions(-)
Index: linux-2.6/kernel/perf_counter.c
===================================================================
--- linux-2.6.orig/kernel/perf_counter.c
+++ linux-2.6/kernel/perf_counter.c
@@ -1663,10 +1663,20 @@ struct perf_output_handle {
unsigned int offset;
unsigned int head;
int wakeup;
+ int nmi;
};

+static inline void __perf_output_wakeup(struct perf_output_handle *handle)
+{
+ if (handle->nmi)
+ perf_pending_queue(handle->counter);
+ else
+ perf_counter_wakeup(handle->counter);
+}
+
static int perf_output_begin(struct perf_output_handle *handle,
- struct perf_counter *counter, unsigned int size)
+ struct perf_counter *counter, unsigned int size,
+ int nmi)
{
struct perf_mmap_data *data;
unsigned int offset, head;
@@ -1676,15 +1686,17 @@ static int perf_output_begin(struct perf
if (!data)
goto out;

+ handle->counter = counter;
+ handle->nmi = nmi;
+
if (!data->nr_pages)
- goto out;
+ goto fail;

do {
offset = head = atomic_read(&data->head);
head += size;
} while (atomic_cmpxchg(&data->head, offset, head) != offset);

- handle->counter = counter;
handle->data = data;
handle->offset = offset;
handle->head = head;
@@ -1692,6 +1704,8 @@ static int perf_output_begin(struct perf

return 0;

+fail:
+ __perf_output_wakeup(handle);
out:
rcu_read_unlock();

@@ -1733,14 +1747,10 @@ static void perf_output_copy(struct perf
#define perf_output_put(handle, x) \
perf_output_copy((handle), &(x), sizeof(x))

-static void perf_output_end(struct perf_output_handle *handle, int nmi)
+static void perf_output_end(struct perf_output_handle *handle)
{
- if (handle->wakeup) {
- if (nmi)
- perf_pending_queue(handle->counter);
- else
- perf_counter_wakeup(handle->counter);
- }
+ if (handle->wakeup)
+ __perf_output_wakeup(handle);
rcu_read_unlock();
}

@@ -1750,12 +1760,12 @@ static int perf_output_write(struct perf
struct perf_output_handle handle;
int ret;

- ret = perf_output_begin(&handle, counter, size);
+ ret = perf_output_begin(&handle, counter, size, nmi);
if (ret)
goto out;

perf_output_copy(&handle, buf, size);
- perf_output_end(&handle, nmi);
+ perf_output_end(&handle);

out:
return ret;
@@ -1804,7 +1814,7 @@ static void perf_output_group(struct per

size = sizeof(header) + counter->nr_siblings * sizeof(entry);

- ret = perf_output_begin(&handle, counter, size);
+ ret = perf_output_begin(&handle, counter, size, nmi);
if (ret)
return;

@@ -1824,7 +1834,7 @@ static void perf_output_group(struct per
perf_output_put(&handle, entry);
}

- perf_output_end(&handle, nmi);
+ perf_output_end(&handle);
}

void perf_counter_output(struct perf_counter *counter,
@@ -1869,7 +1879,7 @@ static void perf_counter_mmap_output(str
{
struct perf_output_handle handle;
int size = mmap_event->event.header.size;
- int ret = perf_output_begin(&handle, counter, size);
+ int ret = perf_output_begin(&handle, counter, size, 0);

if (ret)
return;
@@ -1877,7 +1887,7 @@ static void perf_counter_mmap_output(str
perf_output_put(&handle, mmap_event->event);
perf_output_copy(&handle, mmap_event->file_name,
mmap_event->file_size);
- perf_output_end(&handle, 0);
+ perf_output_end(&handle);
}

static int perf_counter_mmap_match(struct perf_counter *counter,
--



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