--- drivers/oprofile/cpu_buffer.c
+++ drivers/oprofile/cpu_buffer.c
@@ -30,23 +30,7 @@
#define OP_BUFFER_FLAGS 0
-/*
- * Read and write access is using spin locking. Thus, writing to the
- * buffer by NMI handler (x86) could occur also during critical
- * sections when reading the buffer. To avoid this, there are 2
- * buffers for independent read and write access. Read access is in
- * process context only, write access only in the NMI handler. If the
- * read buffer runs empty, both buffers are swapped atomically. There
- * is potentially a small window during swapping where the buffers are
- * disabled and samples could be lost.
- *
- * Using 2 buffers is a little bit overhead, but the solution is clear
- * and does not require changes in the ring buffer implementation. It
- * can be changed to a single buffer solution when the ring buffer
- * access is implemented as non-locking atomic code.
- */
-static struct ring_buffer *op_ring_buffer_read;
-static struct ring_buffer *op_ring_buffer_write;
+static struct ring_buffer *op_ring_buffer;
DEFINE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer);
static void wq_sync_buffer(struct work_struct *work);
@@ -69,12 +53,9 @@ void oprofile_cpu_buffer_inc_smpl_lost(v
void free_cpu_buffers(void)
{
- if (op_ring_buffer_read)
- ring_buffer_free(op_ring_buffer_read);
- op_ring_buffer_read = NULL;
- if (op_ring_buffer_write)
- ring_buffer_free(op_ring_buffer_write);
- op_ring_buffer_write = NULL;
+ if (op_ring_buffer)
+ ring_buffer_free(op_ring_buffer);
+ op_ring_buffer = NULL;
}
#define RB_EVENT_HDR_SIZE 4
@@ -87,11 +68,8 @@ int alloc_cpu_buffers(void)
unsigned long byte_size = buffer_size * (sizeof(struct op_sample) +
RB_EVENT_HDR_SIZE);
- op_ring_buffer_read = ring_buffer_alloc(byte_size, OP_BUFFER_FLAGS);
- if (!op_ring_buffer_read)
- goto fail;
- op_ring_buffer_write = ring_buffer_alloc(byte_size, OP_BUFFER_FLAGS);
- if (!op_ring_buffer_write)
+ op_ring_buffer = ring_buffer_alloc(byte_size, OP_BUFFER_FLAGS);
+ if (!op_ring_buffer)
goto fail;
for_each_possible_cpu(i) {
@@ -163,16 +141,11 @@ 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) +
+ (op_ring_buffer, sizeof(struct op_sample) +
size * sizeof(entry->sample->data[0]));
- if (entry->event)
- entry->sample = ring_buffer_event_data(entry->event);
- else
- entry->sample = NULL;
-
- if (!entry->sample)
+ if (!entry->event)
return NULL;
-
+ entry->sample = ring_buffer_event_data(entry->event);
entry->size = size;
entry->data = entry->sample->data;
@@ -181,25 +154,16 @@ struct op_sample
int op_cpu_buffer_write_commit(struct op_entry *entry)
{
- return ring_buffer_unlock_commit(op_ring_buffer_write, entry->event);
+ return ring_buffer_unlock_commit(op_ring_buffer, entry->event);
}
struct op_sample *op_cpu_buffer_read_entry(struct op_entry *entry, int cpu)
{
struct ring_buffer_event *e;
- e = ring_buffer_consume(op_ring_buffer_read, cpu, NULL);
- if (e)
- goto event;
- if (ring_buffer_swap_cpu(op_ring_buffer_read,
- op_ring_buffer_write,
- cpu))
+ e = ring_buffer_consume(op_ring_buffer, cpu, NULL);
+ if (!e)
return NULL;
- e = ring_buffer_consume(op_ring_buffer_read, cpu, NULL);
- if (e)
- goto event;
- return NULL;
-event:
entry->event = e;
entry->sample = ring_buffer_event_data(e);
entry->size = (ring_buffer_event_length(e) - sizeof(struct op_sample))
@@ -210,8 +174,7 @@ event:
unsigned long op_cpu_buffer_entries(int cpu)
{
- return ring_buffer_entries_cpu(op_ring_buffer_read, cpu)
- + ring_buffer_entries_cpu(op_ring_buffer_write, cpu);
+ return ring_buffer_entries_cpu(op_ring_buffer, cpu);
}
static int
projects / ziggy471-frankenstein-kernel.git / blobdiff