ftrace: cleanups
factor out code and clean it up.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f6d026f..61d2f02 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -142,12 +142,59 @@
tracing_record_cmdline(current);
}
+void check_pages(struct trace_array_cpu *data)
+{
+ struct page *page, *tmp;
+
+ BUG_ON(data->trace_pages.next->prev != &data->trace_pages);
+ BUG_ON(data->trace_pages.prev->next != &data->trace_pages);
+
+ list_for_each_entry_safe(page, tmp, &data->trace_pages, lru) {
+ BUG_ON(page->lru.next->prev != &page->lru);
+ BUG_ON(page->lru.prev->next != &page->lru);
+ }
+}
+
+void *head_page(struct trace_array_cpu *data)
+{
+ struct page *page;
+
+ check_pages(data);
+ if (list_empty(&data->trace_pages))
+ return NULL;
+
+ page = list_entry(data->trace_pages.next, struct page, lru);
+ BUG_ON(&page->lru == &data->trace_pages);
+
+ return page_address(page);
+}
+
+notrace static void
+flip_trace(struct trace_array_cpu *tr1, struct trace_array_cpu *tr2)
+{
+ struct list_head flip_pages;
+
+ INIT_LIST_HEAD(&flip_pages);
+
+ tr1->trace_current = NULL;
+ memcpy(&tr1->trace_current_idx, &tr2->trace_current_idx,
+ sizeof(struct trace_array_cpu) -
+ offsetof(struct trace_array_cpu, trace_current_idx));
+
+ check_pages(tr1);
+ check_pages(tr2);
+ list_splice_init(&tr1->trace_pages, &flip_pages);
+ list_splice_init(&tr2->trace_pages, &tr1->trace_pages);
+ list_splice_init(&flip_pages, &tr2->trace_pages);
+ BUG_ON(!list_empty(&flip_pages));
+ check_pages(tr1);
+ check_pages(tr2);
+}
+
notrace void
update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
struct trace_array_cpu *data;
- void *save_trace;
- struct list_head save_pages;
int i;
WARN_ON_ONCE(!irqs_disabled());
@@ -155,11 +202,7 @@
/* clear out all the previous traces */
for_each_possible_cpu(i) {
data = tr->data[i];
- save_trace = max_tr.data[i]->trace;
- save_pages = max_tr.data[i]->trace_pages;
- memcpy(max_tr.data[i], data, sizeof(*data));
- data->trace = save_trace;
- data->trace_pages = save_pages;
+ flip_trace(max_tr.data[i], data);
tracing_reset(data);
}
@@ -177,8 +220,6 @@
update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
struct trace_array_cpu *data = tr->data[cpu];
- void *save_trace;
- struct list_head save_pages;
int i;
WARN_ON_ONCE(!irqs_disabled());
@@ -186,11 +227,8 @@
for_each_possible_cpu(i)
tracing_reset(max_tr.data[i]);
- save_trace = max_tr.data[cpu]->trace;
- save_pages = max_tr.data[cpu]->trace_pages;
- memcpy(max_tr.data[cpu], data, sizeof(*data));
- data->trace = save_trace;
- data->trace_pages = save_pages;
+ flip_trace(max_tr.data[cpu], data);
+
tracing_reset(data);
__update_max_tr(tr, tsk, cpu);
@@ -234,9 +272,9 @@
* If we fail, we do not register this tracer.
*/
for_each_possible_cpu(i) {
- if (!data->trace)
- continue;
data = tr->data[i];
+ if (!head_page(data))
+ continue;
tracing_reset(data);
}
current_trace = type;
@@ -298,7 +336,7 @@
void notrace tracing_reset(struct trace_array_cpu *data)
{
data->trace_idx = 0;
- data->trace_current = data->trace;
+ data->trace_current = head_page(data);
data->trace_current_idx = 0;
}
@@ -425,26 +463,31 @@
}
static inline notrace struct trace_entry *
-tracing_get_trace_entry(struct trace_array *tr,
- struct trace_array_cpu *data)
+tracing_get_trace_entry(struct trace_array *tr, struct trace_array_cpu *data)
{
unsigned long idx, idx_next;
struct trace_entry *entry;
- struct page *page;
struct list_head *next;
+ struct page *page;
data->trace_idx++;
idx = data->trace_current_idx;
idx_next = idx + 1;
+ BUG_ON(idx * TRACE_ENTRY_SIZE >= PAGE_SIZE);
+
entry = data->trace_current + idx * TRACE_ENTRY_SIZE;
if (unlikely(idx_next >= ENTRIES_PER_PAGE)) {
page = virt_to_page(data->trace_current);
- if (unlikely(&page->lru == data->trace_pages.prev))
- next = data->trace_pages.next;
- else
- next = page->lru.next;
+ /*
+ * Roundrobin - but skip the head (which is not a real page):
+ */
+ next = page->lru.next;
+ if (unlikely(next == &data->trace_pages))
+ next = next->next;
+ BUG_ON(next == &data->trace_pages);
+
page = list_entry(next, struct page, lru);
data->trace_current = page_address(page);
idx_next = 0;
@@ -456,18 +499,17 @@
}
static inline notrace void
-tracing_generic_entry_update(struct trace_entry *entry,
- unsigned long flags)
+tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags)
{
struct task_struct *tsk = current;
unsigned long pc;
pc = preempt_count();
- entry->idx = atomic_inc_return(&tracer_counter);
- entry->preempt_count = pc & 0xff;
- entry->pid = tsk->pid;
- entry->t = now(raw_smp_processor_id());
+ entry->idx = atomic_inc_return(&tracer_counter);
+ entry->preempt_count = pc & 0xff;
+ entry->pid = tsk->pid;
+ entry->t = now(raw_smp_processor_id());
entry->flags = (irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
@@ -476,16 +518,15 @@
notrace void
ftrace(struct trace_array *tr, struct trace_array_cpu *data,
- unsigned long ip, unsigned long parent_ip,
- unsigned long flags)
+ unsigned long ip, unsigned long parent_ip, unsigned long flags)
{
struct trace_entry *entry;
- entry = tracing_get_trace_entry(tr, data);
+ entry = tracing_get_trace_entry(tr, data);
tracing_generic_entry_update(entry, flags);
- entry->type = TRACE_FN;
- entry->fn.ip = ip;
- entry->fn.parent_ip = parent_ip;
+ entry->type = TRACE_FN;
+ entry->fn.ip = ip;
+ entry->fn.parent_ip = parent_ip;
}
notrace void
@@ -496,7 +537,7 @@
{
struct trace_entry *entry;
- entry = tracing_get_trace_entry(tr, data);
+ entry = tracing_get_trace_entry(tr, data);
tracing_generic_entry_update(entry, flags);
entry->type = TRACE_CTX;
entry->ctx.prev_pid = prev->pid;
@@ -540,6 +581,8 @@
}
page = list_entry(iter->next_page[cpu], struct page, lru);
+ BUG_ON(&data->trace_pages == &page->lru);
+
array = page_address(page);
return &array[iter->next_page_idx[cpu]];
@@ -554,7 +597,7 @@
int cpu;
for_each_possible_cpu(cpu) {
- if (!tr->data[cpu]->trace)
+ if (!head_page(tr->data[cpu]))
continue;
ent = trace_entry_idx(tr, tr->data[cpu], iter, cpu);
if (ent &&
@@ -762,7 +805,7 @@
name = type->name;
for_each_possible_cpu(cpu) {
- if (tr->data[cpu]->trace) {
+ if (head_page(tr->data[cpu])) {
total += tr->data[cpu]->trace_idx;
if (tr->data[cpu]->trace_idx > tr->entries)
entries += tr->entries;
@@ -975,8 +1018,7 @@
for_each_possible_cpu(cpu) {
data = iter->tr->data[cpu];
- if (data->trace &&
- data->trace_idx)
+ if (head_page(data) && data->trace_idx)
return 0;
}
return 1;
@@ -1576,9 +1618,9 @@
static int trace_alloc_page(void)
{
struct trace_array_cpu *data;
- void *array;
struct page *page, *tmp;
LIST_HEAD(pages);
+ void *array;
int i;
/* first allocate a page for each CPU */
@@ -1610,14 +1652,14 @@
for_each_possible_cpu(i) {
data = global_trace.data[i];
page = list_entry(pages.next, struct page, lru);
- list_del(&page->lru);
+ list_del_init(&page->lru);
list_add_tail(&page->lru, &data->trace_pages);
ClearPageLRU(page);
#ifdef CONFIG_TRACER_MAX_TRACE
data = max_tr.data[i];
page = list_entry(pages.next, struct page, lru);
- list_del(&page->lru);
+ list_del_init(&page->lru);
list_add_tail(&page->lru, &data->trace_pages);
SetPageLRU(page);
#endif
@@ -1628,7 +1670,7 @@
free_pages:
list_for_each_entry_safe(page, tmp, &pages, lru) {
- list_del(&page->lru);
+ list_del_init(&page->lru);
__free_page(page);
}
return -ENOMEM;
@@ -1654,7 +1696,6 @@
"for trace buffer!\n");
goto free_buffers;
}
- data->trace = array;
/* set the array to the list */
INIT_LIST_HEAD(&data->trace_pages);
@@ -1671,7 +1712,6 @@
"for trace buffer!\n");
goto free_buffers;
}
- max_tr.data[i]->trace = array;
INIT_LIST_HEAD(&max_tr.data[i]->trace_pages);
page = virt_to_page(array);
@@ -1716,24 +1756,22 @@
struct page *page, *tmp;
struct trace_array_cpu *data = global_trace.data[i];
- if (data && data->trace) {
+ if (data) {
list_for_each_entry_safe(page, tmp,
&data->trace_pages, lru) {
- list_del(&page->lru);
+ list_del_init(&page->lru);
__free_page(page);
}
- data->trace = NULL;
}
#ifdef CONFIG_TRACER_MAX_TRACE
data = max_tr.data[i];
- if (data && data->trace) {
+ if (data) {
list_for_each_entry_safe(page, tmp,
&data->trace_pages, lru) {
- list_del(&page->lru);
+ list_del_init(&page->lru);
__free_page(page);
}
- data->trace = NULL;
}
#endif
}