Merge tag 'trace-v4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:

 - Rework of the kprobe/uprobe and synthetic events to consolidate all
   the dynamic event code. This will make changes in the future easier.

 - Partial rewrite of the function graph tracing infrastructure. This
   will allow for multiple users of hooking onto functions to get the
   callback (return) of the function. This is the ground work for having
   kprobes and function graph tracer using one code base.

 - Clean up of the histogram code that will facilitate adding more
   features to the histograms in the future.

 - Addition of str_has_prefix() and a few use cases. There currently is
   a similar function strstart() that is used in a few places, but only
   returns a bool and not a length. These instances will be removed in
   the future to use str_has_prefix() instead.

 - A few other various clean ups as well.

* tag 'trace-v4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (57 commits)
  tracing: Use the return of str_has_prefix() to remove open coded numbers
  tracing: Have the historgram use the result of str_has_prefix() for len of prefix
  tracing: Use str_has_prefix() instead of using fixed sizes
  tracing: Use str_has_prefix() helper for histogram code
  string.h: Add str_has_prefix() helper function
  tracing: Make function ‘ftrace_exports’ static
  tracing: Simplify printf'ing in seq_print_sym
  tracing: Avoid -Wformat-nonliteral warning
  tracing: Merge seq_print_sym_short() and seq_print_sym_offset()
  tracing: Add hist trigger comments for variable-related fields
  tracing: Remove hist trigger synth_var_refs
  tracing: Use hist trigger's var_ref array to destroy var_refs
  tracing: Remove open-coding of hist trigger var_ref management
  tracing: Use var_refs[] for hist trigger reference checking
  tracing: Change strlen to sizeof for hist trigger static strings
  tracing: Remove unnecessary hist trigger struct field
  tracing: Fix ftrace_graph_get_ret_stack() to use task and not current
  seq_buf: Use size_t for len in seq_buf_puts()
  seq_buf: Make seq_buf_puts() null-terminate the buffer
  arm64: Use ftrace_graph_get_ret_stack() instead of curr_ret_stack
  ...

1 files changed, 74 insertions, 8 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 51612b4a603f..c521b7347482 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1431,7 +1431,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
 }
 #endif /* CONFIG_TRACER_MAX_TRACE */
 
-static int wait_on_pipe(struct trace_iterator *iter, bool full)
+static int wait_on_pipe(struct trace_iterator *iter, int full)
 {
 	/* Iterators are static, they should be filled or empty */
 	if (trace_buffer_iter(iter, iter->cpu_file))
@@ -2452,7 +2452,7 @@ static inline void ftrace_exports_disable(void)
 	static_branch_disable(&ftrace_exports_enabled);
 }
 
-void ftrace_exports(struct ring_buffer_event *event)
+static void ftrace_exports(struct ring_buffer_event *event)
 {
 	struct trace_export *export;
 
@@ -4408,13 +4408,15 @@ static int trace_set_options(struct trace_array *tr, char *option)
 	int neg = 0;
 	int ret;
 	size_t orig_len = strlen(option);
+	int len;
 
 	cmp = strstrip(option);
 
-	if (strncmp(cmp, "no", 2) == 0) {
+	len = str_has_prefix(cmp, "no");
+	if (len)
 		neg = 1;
-		cmp += 2;
-	}
+
+	cmp += len;
 
 	mutex_lock(&trace_types_lock);
 
@@ -4604,6 +4606,10 @@ static const char readme_msg[] =
 	"\t\t\t  traces\n"
 #endif
 #endif /* CONFIG_STACK_TRACER */
+#ifdef CONFIG_DYNAMIC_EVENTS
+	"  dynamic_events\t\t- Add/remove/show the generic dynamic events\n"
+	"\t\t\t  Write into this file to define/undefine new trace events.\n"
+#endif
 #ifdef CONFIG_KPROBE_EVENTS
 	"  kprobe_events\t\t- Add/remove/show the kernel dynamic events\n"
 	"\t\t\t  Write into this file to define/undefine new trace events.\n"
@@ -4616,6 +4622,9 @@ static const char readme_msg[] =
 	"\t  accepts: event-definitions (one definition per line)\n"
 	"\t   Format: p[:[<group>/]<event>] <place> [<args>]\n"
 	"\t           r[maxactive][:[<group>/]<event>] <place> [<args>]\n"
+#ifdef CONFIG_HIST_TRIGGERS
+	"\t           s:[synthetic/]<event> <field> [<field>]\n"
+#endif
 	"\t           -:[<group>/]<event>\n"
 #ifdef CONFIG_KPROBE_EVENTS
 	"\t    place: [<module>:]<symbol>[+<offset>]|<memaddr>\n"
@@ -4634,6 +4643,11 @@ static const char readme_msg[] =
 	"\t     type: s8/16/32/64, u8/16/32/64, x8/16/32/64, string, symbol,\n"
 	"\t           b<bit-width>@<bit-offset>/<container-size>,\n"
 	"\t           <type>\\[<array-size>\\]\n"
+#ifdef CONFIG_HIST_TRIGGERS
+	"\t    field: <stype> <name>;\n"
+	"\t    stype: u8/u16/u32/u64, s8/s16/s32/s64, pid_t,\n"
+	"\t           [unsigned] char/int/long\n"
+#endif
 #endif
 	"  events/\t\t- Directory containing all trace event subsystems:\n"
 	"      enable\t\t- Write 0/1 to enable/disable tracing of all events\n"
@@ -5693,7 +5707,7 @@ static int tracing_wait_pipe(struct file *filp)
 
 		mutex_unlock(&iter->mutex);
 
-		ret = wait_on_pipe(iter, false);
+		ret = wait_on_pipe(iter, 0);
 
 		mutex_lock(&iter->mutex);
 
@@ -6751,7 +6765,7 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
 			if ((filp->f_flags & O_NONBLOCK))
 				return -EAGAIN;
 
-			ret = wait_on_pipe(iter, false);
+			ret = wait_on_pipe(iter, 0);
 			if (ret)
 				return ret;
 
@@ -6948,7 +6962,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 		if ((file->f_flags & O_NONBLOCK) || (flags & SPLICE_F_NONBLOCK))
 			goto out;
 
-		ret = wait_on_pipe(iter, true);
+		ret = wait_on_pipe(iter, iter->tr->buffer_percent);
 		if (ret)
 			goto out;
 
@@ -7662,6 +7676,53 @@ static const struct file_operations rb_simple_fops = {
 	.llseek		= default_llseek,
 };
 
+static ssize_t
+buffer_percent_read(struct file *filp, char __user *ubuf,
+		    size_t cnt, loff_t *ppos)
+{
+	struct trace_array *tr = filp->private_data;
+	char buf[64];
+	int r;
+
+	r = tr->buffer_percent;
+	r = sprintf(buf, "%d\n", r);
+
+	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static ssize_t
+buffer_percent_write(struct file *filp, const char __user *ubuf,
+		     size_t cnt, loff_t *ppos)
+{
+	struct trace_array *tr = filp->private_data;
+	unsigned long val;
+	int ret;
+
+	ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+	if (ret)
+		return ret;
+
+	if (val > 100)
+		return -EINVAL;
+
+	if (!val)
+		val = 1;
+
+	tr->buffer_percent = val;
+
+	(*ppos)++;
+
+	return cnt;
+}
+
+static const struct file_operations buffer_percent_fops = {
+	.open		= tracing_open_generic_tr,
+	.read		= buffer_percent_read,
+	.write		= buffer_percent_write,
+	.release	= tracing_release_generic_tr,
+	.llseek		= default_llseek,
+};
+
 struct dentry *trace_instance_dir;
 
 static void
@@ -7970,6 +8031,11 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
 	trace_create_file("timestamp_mode", 0444, d_tracer, tr,
 			  &trace_time_stamp_mode_fops);
 
+	tr->buffer_percent = 50;
+
+	trace_create_file("buffer_percent", 0444, d_tracer,
+			tr, &buffer_percent_fops);
+
 	create_trace_options_dir(tr);
 
 #if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)