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Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/ring_buffer.c104
-rw-r--r--kernel/trace/trace_output.c35
-rw-r--r--kernel/trace/trace_stack.c2
3 files changed, 81 insertions, 60 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 16b24d49604..7102d7a2fad 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -370,6 +370,9 @@ static inline int test_time_stamp(u64 delta)
/* Max payload is BUF_PAGE_SIZE - header (8bytes) */
#define BUF_MAX_DATA_SIZE (BUF_PAGE_SIZE - (sizeof(u32) * 2))
+/* Max number of timestamps that can fit on a page */
+#define RB_TIMESTAMPS_PER_PAGE (BUF_PAGE_SIZE / RB_LEN_TIME_STAMP)
+
int ring_buffer_print_page_header(struct trace_seq *s)
{
struct buffer_data_page field;
@@ -1335,6 +1338,38 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
return event;
}
+static inline int
+rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer,
+ struct ring_buffer_event *event)
+{
+ unsigned long new_index, old_index;
+ struct buffer_page *bpage;
+ unsigned long index;
+ unsigned long addr;
+
+ new_index = rb_event_index(event);
+ old_index = new_index + rb_event_length(event);
+ addr = (unsigned long)event;
+ addr &= PAGE_MASK;
+
+ bpage = cpu_buffer->tail_page;
+
+ if (bpage->page == (void *)addr && rb_page_write(bpage) == old_index) {
+ /*
+ * This is on the tail page. It is possible that
+ * a write could come in and move the tail page
+ * and write to the next page. That is fine
+ * because we just shorten what is on this page.
+ */
+ index = local_cmpxchg(&bpage->write, old_index, new_index);
+ if (index == old_index)
+ return 1;
+ }
+
+ /* could not discard */
+ return 0;
+}
+
static int
rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer,
u64 *ts, u64 *delta)
@@ -1377,17 +1412,24 @@ rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer,
event->array[0] = *delta >> TS_SHIFT;
} else {
cpu_buffer->commit_page->page->time_stamp = *ts;
- event->time_delta = 0;
- event->array[0] = 0;
+ /* try to discard, since we do not need this */
+ if (!rb_try_to_discard(cpu_buffer, event)) {
+ /* nope, just zero it */
+ event->time_delta = 0;
+ event->array[0] = 0;
+ }
}
cpu_buffer->write_stamp = *ts;
/* let the caller know this was the commit */
ret = 1;
} else {
- /* Darn, this is just wasted space */
- event->time_delta = 0;
- event->array[0] = 0;
- ret = 0;
+ /* Try to discard the event */
+ if (!rb_try_to_discard(cpu_buffer, event)) {
+ /* Darn, this is just wasted space */
+ event->time_delta = 0;
+ event->array[0] = 0;
+ ret = 0;
+ }
}
*delta = 0;
@@ -1682,10 +1724,6 @@ void ring_buffer_discard_commit(struct ring_buffer *buffer,
struct ring_buffer_event *event)
{
struct ring_buffer_per_cpu *cpu_buffer;
- unsigned long new_index, old_index;
- struct buffer_page *bpage;
- unsigned long index;
- unsigned long addr;
int cpu;
/* The event is discarded regardless */
@@ -1701,24 +1739,8 @@ void ring_buffer_discard_commit(struct ring_buffer *buffer,
cpu = smp_processor_id();
cpu_buffer = buffer->buffers[cpu];
- new_index = rb_event_index(event);
- old_index = new_index + rb_event_length(event);
- addr = (unsigned long)event;
- addr &= PAGE_MASK;
-
- bpage = cpu_buffer->tail_page;
-
- if (bpage == (void *)addr && rb_page_write(bpage) == old_index) {
- /*
- * This is on the tail page. It is possible that
- * a write could come in and move the tail page
- * and write to the next page. That is fine
- * because we just shorten what is on this page.
- */
- index = local_cmpxchg(&bpage->write, old_index, new_index);
- if (index == old_index)
- goto out;
- }
+ if (!rb_try_to_discard(cpu_buffer, event))
+ goto out;
/*
* The commit is still visible by the reader, so we
@@ -2253,8 +2275,8 @@ static void rb_advance_iter(struct ring_buffer_iter *iter)
* Check if we are at the end of the buffer.
*/
if (iter->head >= rb_page_size(iter->head_page)) {
- if (RB_WARN_ON(buffer,
- iter->head_page == cpu_buffer->commit_page))
+ /* discarded commits can make the page empty */
+ if (iter->head_page == cpu_buffer->commit_page)
return;
rb_inc_iter(iter);
return;
@@ -2297,12 +2319,10 @@ rb_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts)
/*
* We repeat when a timestamp is encountered. It is possible
* to get multiple timestamps from an interrupt entering just
- * as one timestamp is about to be written. The max times
- * that this can happen is the number of nested interrupts we
- * can have. Nesting 10 deep of interrupts is clearly
- * an anomaly.
+ * as one timestamp is about to be written, or from discarded
+ * commits. The most that we can have is the number on a single page.
*/
- if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10))
+ if (RB_WARN_ON(cpu_buffer, ++nr_loops > RB_TIMESTAMPS_PER_PAGE))
return NULL;
reader = rb_get_reader_page(cpu_buffer);
@@ -2368,14 +2388,14 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
again:
/*
- * We repeat when a timestamp is encountered. It is possible
- * to get multiple timestamps from an interrupt entering just
- * as one timestamp is about to be written. The max times
- * that this can happen is the number of nested interrupts we
- * can have. Nesting 10 deep of interrupts is clearly
- * an anomaly.
+ * We repeat when a timestamp is encountered.
+ * We can get multiple timestamps by nested interrupts or also
+ * if filtering is on (discarding commits). Since discarding
+ * commits can be frequent we can get a lot of timestamps.
+ * But we limit them by not adding timestamps if they begin
+ * at the start of a page.
*/
- if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10))
+ if (RB_WARN_ON(cpu_buffer, ++nr_loops > RB_TIMESTAMPS_PER_PAGE))
return NULL;
if (rb_per_cpu_empty(cpu_buffer))
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 0fe3b223f7e..425725c1622 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -223,10 +223,9 @@ ftrace_print_flags_seq(struct trace_seq *p, const char *delim,
{
unsigned long mask;
const char *str;
+ const char *ret = p->buffer + p->len;
int i;
- trace_seq_init(p);
-
for (i = 0; flag_array[i].name && flags; i++) {
mask = flag_array[i].mask;
@@ -249,7 +248,7 @@ ftrace_print_flags_seq(struct trace_seq *p, const char *delim,
trace_seq_putc(p, 0);
- return p->buffer;
+ return ret;
}
EXPORT_SYMBOL(ftrace_print_flags_seq);
@@ -258,8 +257,7 @@ ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val,
const struct trace_print_flags *symbol_array)
{
int i;
-
- trace_seq_init(p);
+ const char *ret = p->buffer + p->len;
for (i = 0; symbol_array[i].name; i++) {
@@ -275,7 +273,7 @@ ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val,
trace_seq_putc(p, 0);
- return p->buffer;
+ return ret;
}
EXPORT_SYMBOL(ftrace_print_symbols_seq);
@@ -389,17 +387,20 @@ seq_print_userip_objs(const struct userstack_entry *entry, struct trace_seq *s,
if (ip == ULONG_MAX || !ret)
break;
- if (i && ret)
- ret = trace_seq_puts(s, " <- ");
+ if (ret)
+ ret = trace_seq_puts(s, " => ");
if (!ip) {
if (ret)
ret = trace_seq_puts(s, "??");
+ if (ret)
+ ret = trace_seq_puts(s, "\n");
continue;
}
if (!ret)
break;
if (ret)
ret = seq_print_user_ip(s, mm, ip, sym_flags);
+ ret = trace_seq_puts(s, "\n");
}
if (mm)
@@ -975,16 +976,16 @@ static enum print_line_t trace_stack_print(struct trace_iterator *iter,
trace_assign_type(field, iter->ent);
+ if (!trace_seq_puts(s, "<stack trace>\n"))
+ goto partial;
for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
- if (!field->caller[i])
+ if (!field->caller[i] || (field->caller[i] == ULONG_MAX))
break;
- if (i) {
- if (!trace_seq_puts(s, " <= "))
- goto partial;
+ if (!trace_seq_puts(s, " => "))
+ goto partial;
- if (!seq_print_ip_sym(s, field->caller[i], flags))
- goto partial;
- }
+ if (!seq_print_ip_sym(s, field->caller[i], flags))
+ goto partial;
if (!trace_seq_puts(s, "\n"))
goto partial;
}
@@ -1012,10 +1013,10 @@ static enum print_line_t trace_user_stack_print(struct trace_iterator *iter,
trace_assign_type(field, iter->ent);
- if (!seq_print_userip_objs(field, s, flags))
+ if (!trace_seq_puts(s, "<user stack trace>\n"))
goto partial;
- if (!trace_seq_putc(s, '\n'))
+ if (!seq_print_userip_objs(field, s, flags))
goto partial;
return TRACE_TYPE_HANDLED;
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index 1796f00524e..2d7aebd71db 100644
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -265,7 +265,7 @@ static int t_show(struct seq_file *m, void *v)
seq_printf(m, " Depth Size Location"
" (%d entries)\n"
" ----- ---- --------\n",
- max_stack_trace.nr_entries);
+ max_stack_trace.nr_entries - 1);
if (!stack_tracer_enabled && !max_stack_size)
print_disabled(m);
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-12 09:53:10 +0000