aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--include/linux/ftrace_event.h1
-rw-r--r--include/linux/trace_seq.h5
-rw-r--r--kernel/trace/trace.c35
-rw-r--r--kernel/trace/trace_output.c14
4 files changed, 47 insertions, 8 deletions
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 47bbdf9c38d..38f8d655383 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -57,6 +57,7 @@ struct trace_iterator {
/* The below is zeroed out in pipe_read */
struct trace_seq seq;
struct trace_entry *ent;
+ int leftover;
int cpu;
u64 ts;
diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index 09077f6ed12..fad6857bc0f 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -33,7 +33,7 @@ extern int trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
__attribute__ ((format (printf, 2, 0)));
extern int
trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary);
-extern void trace_print_seq(struct seq_file *m, struct trace_seq *s);
+extern int trace_print_seq(struct seq_file *m, struct trace_seq *s);
extern ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
size_t cnt);
extern int trace_seq_puts(struct trace_seq *s, const char *str);
@@ -55,8 +55,9 @@ trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
return 0;
}
-static inline void trace_print_seq(struct seq_file *m, struct trace_seq *s)
+static inline int trace_print_seq(struct seq_file *m, struct trace_seq *s)
{
+ return 0;
}
static inline ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
size_t cnt)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index dc937e1baa9..484114d7074 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1516,6 +1516,8 @@ static void *s_next(struct seq_file *m, void *v, loff_t *pos)
int i = (int)*pos;
void *ent;
+ WARN_ON_ONCE(iter->leftover);
+
(*pos)++;
/* can't go backwards */
@@ -1614,8 +1616,16 @@ static void *s_start(struct seq_file *m, loff_t *pos)
;
} else {
- l = *pos - 1;
- p = s_next(m, p, &l);
+ /*
+ * If we overflowed the seq_file before, then we want
+ * to just reuse the trace_seq buffer again.
+ */
+ if (iter->leftover)
+ p = iter;
+ else {
+ l = *pos - 1;
+ p = s_next(m, p, &l);
+ }
}
trace_event_read_lock();
@@ -1923,6 +1933,7 @@ static enum print_line_t print_trace_line(struct trace_iterator *iter)
static int s_show(struct seq_file *m, void *v)
{
struct trace_iterator *iter = v;
+ int ret;
if (iter->ent == NULL) {
if (iter->tr) {
@@ -1942,9 +1953,27 @@ static int s_show(struct seq_file *m, void *v)
if (!(trace_flags & TRACE_ITER_VERBOSE))
print_func_help_header(m);
}
+ } else if (iter->leftover) {
+ /*
+ * If we filled the seq_file buffer earlier, we
+ * want to just show it now.
+ */
+ ret = trace_print_seq(m, &iter->seq);
+
+ /* ret should this time be zero, but you never know */
+ iter->leftover = ret;
+
} else {
print_trace_line(iter);
- trace_print_seq(m, &iter->seq);
+ ret = trace_print_seq(m, &iter->seq);
+ /*
+ * If we overflow the seq_file buffer, then it will
+ * ask us for this data again at start up.
+ * Use that instead.
+ * ret is 0 if seq_file write succeeded.
+ * -1 otherwise.
+ */
+ iter->leftover = ret;
}
return 0;
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index b6c12c6a1bc..e5cf90fef34 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -23,13 +23,21 @@ static struct hlist_head event_hash[EVENT_HASHSIZE] __read_mostly;
static int next_event_type = __TRACE_LAST_TYPE + 1;
-void trace_print_seq(struct seq_file *m, struct trace_seq *s)
+int trace_print_seq(struct seq_file *m, struct trace_seq *s)
{
int len = s->len >= PAGE_SIZE ? PAGE_SIZE - 1 : s->len;
+ int ret;
+
+ ret = seq_write(m, s->buffer, len);
- seq_write(m, s->buffer, len);
+ /*
+ * Only reset this buffer if we successfully wrote to the
+ * seq_file buffer.
+ */
+ if (!ret)
+ trace_seq_init(s);
- trace_seq_init(s);
+ return ret;
}
enum print_line_t trace_print_bprintk_msg_only(struct trace_iterator *iter)