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Subject[PATCH 1/9] oprofile: add op_cpu_buffer_write_reserve()
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This function prepares the cpu buffer to write a sample.

Struct op_entry is used during operations on the ring buffer while
struct op_sample contains the data that is stored in the ring
buffer. Struct entry can be uninitialized. The function reserves a
data array that is specified by size. Use op_cpu_buffer_write_commit()
after preparing the sample. In case of errors a null pointer is
returned, otherwise the pointer to the sample.

Signed-off-by: Robert Richter <robert.richter@amd.com>
---
drivers/oprofile/cpu_buffer.c | 43 ++++++++++++++++++++++++++++------------
drivers/oprofile/cpu_buffer.h | 9 ++++++-
2 files changed, 37 insertions(+), 15 deletions(-)

diff --git a/drivers/oprofile/cpu_buffer.c b/drivers/oprofile/cpu_buffer.c
index ac79f66..934ff15 100644
--- a/drivers/oprofile/cpu_buffer.c
+++ b/drivers/oprofile/cpu_buffer.c
@@ -1,11 +1,12 @@
/**
* @file cpu_buffer.c
*
- * @remark Copyright 2002 OProfile authors
+ * @remark Copyright 2002-2009 OProfile authors
* @remark Read the file COPYING
*
* @author John Levon <levon@movementarian.org>
* @author Barry Kasindorf <barry.kasindorf@amd.com>
+ * @author Robert Richter <robert.richter@amd.com>
*
* Each CPU has a local buffer that stores PC value/event
* pairs. We also log context switches when we notice them.
@@ -143,20 +144,36 @@ void end_cpu_work(void)
flush_scheduled_work();
}

-int op_cpu_buffer_write_entry(struct op_entry *entry)
+/*
+ * This function prepares the cpu buffer to write a sample.
+ *
+ * Struct op_entry is used during operations on the ring buffer while
+ * struct op_sample contains the data that is stored in the ring
+ * buffer. Struct entry can be uninitialized. The function reserves a
+ * data array that is specified by size. Use
+ * op_cpu_buffer_write_commit() after preparing the sample. In case of
+ * errors a null pointer is returned, otherwise the pointer to the
+ * sample.
+ *
+ */
+struct op_sample
+*op_cpu_buffer_write_reserve(struct op_entry *entry, unsigned long size)
{
- entry->event = ring_buffer_lock_reserve(op_ring_buffer_write,
- sizeof(struct op_sample),
- &entry->irq_flags);
+ entry->event = ring_buffer_lock_reserve
+ (op_ring_buffer_write, sizeof(struct op_sample) +
+ size * sizeof(entry->sample->data[0]), &entry->irq_flags);
if (entry->event)
entry->sample = ring_buffer_event_data(entry->event);
else
entry->sample = NULL;

if (!entry->sample)
- return -ENOMEM;
+ return NULL;

- return 0;
+ entry->size = size;
+ entry->data = entry->sample->data;
+
+ return entry->sample;
}

int op_cpu_buffer_write_commit(struct op_entry *entry)
@@ -192,14 +209,14 @@ op_add_sample(struct oprofile_cpu_buffer *cpu_buf,
unsigned long pc, unsigned long event)
{
struct op_entry entry;
- int ret;
+ struct op_sample *sample;

- ret = op_cpu_buffer_write_entry(&entry);
- if (ret)
- return ret;
+ sample = op_cpu_buffer_write_reserve(&entry, 0);
+ if (!sample)
+ return -ENOMEM;

- entry.sample->eip = pc;
- entry.sample->event = event;
+ sample->eip = pc;
+ sample->event = event;

return op_cpu_buffer_write_commit(&entry);
}
diff --git a/drivers/oprofile/cpu_buffer.h b/drivers/oprofile/cpu_buffer.h
index 65b763a..2d4bfde 100644
--- a/drivers/oprofile/cpu_buffer.h
+++ b/drivers/oprofile/cpu_buffer.h
@@ -1,10 +1,11 @@
/**
* @file cpu_buffer.h
*
- * @remark Copyright 2002 OProfile authors
+ * @remark Copyright 2002-2009 OProfile authors
* @remark Read the file COPYING
*
* @author John Levon <levon@movementarian.org>
+ * @author Robert Richter <robert.richter@amd.com>
*/

#ifndef OPROFILE_CPU_BUFFER_H
@@ -31,12 +32,15 @@ void end_cpu_work(void);
struct op_sample {
unsigned long eip;
unsigned long event;
+ unsigned long data[0];
};

struct op_entry {
struct ring_buffer_event *event;
struct op_sample *sample;
unsigned long irq_flags;
+ unsigned long size;
+ unsigned long *data;
};

struct oprofile_cpu_buffer {
@@ -68,7 +72,8 @@ static inline void op_cpu_buffer_reset(int cpu)
cpu_buf->last_task = NULL;
}

-int op_cpu_buffer_write_entry(struct op_entry *entry);
+struct op_sample
+*op_cpu_buffer_write_reserve(struct op_entry *entry, unsigned long size);
int op_cpu_buffer_write_commit(struct op_entry *entry);
struct op_sample *op_cpu_buffer_read_entry(int cpu);
unsigned long op_cpu_buffer_entries(int cpu);
--
1.6.0.1



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