linux-kernel - [PATCH v2 3/4] tracing: Add trace_array

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Message-ID: <20230207173026.584717290@goodmis.org>
Date:   Tue, 07 Feb 2023 12:28:52 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ross Zwisler <zwisler@...gle.com>
Subject: [PATCH v2 3/4] tracing: Add trace_array_puts() to write into instance

From: "Steven Rostedt (Google)" <rostedt@...dmis.org>

Add a generic trace_array_puts() that can be used to "trace_puts()" into
an allocated trace_array instance. This is just another variant of
trace_array_printk().

Reviewed-by: Ross Zwisler <zwisler@...gle.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
Changes since v1: https://lkml.kernel.org/r/20230111145842.694147820@goodmis.org
- Remove unneeded @ip in kernel-doc (Ross Zwisler)

 include/linux/trace.h | 12 ++++++++++++
 kernel/trace/trace.c  | 27 +++++++++++++++++----------
 2 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/include/linux/trace.h b/include/linux/trace.h
index 80ffda871749..2a70a447184c 100644
--- a/include/linux/trace.h
+++ b/include/linux/trace.h
@@ -33,6 +33,18 @@ struct trace_array;
 int register_ftrace_export(struct trace_export *export);
 int unregister_ftrace_export(struct trace_export *export);
 
+/**
+ * trace_array_puts - write a constant string into the trace buffer.
+ * @tr:    The trace array to write to
+ * @str:   The constant string to write
+ */
+#define trace_array_puts(tr, str)					\
+	({								\
+		str ? __trace_array_puts(tr, _THIS_IP_, str, strlen(str)) : -1;	\
+	})
+int __trace_array_puts(struct trace_array *tr, unsigned long ip,
+		       const char *str, int size);
+
 void trace_printk_init_buffers(void);
 __printf(3, 4)
 int trace_array_printk(struct trace_array *tr, unsigned long ip,
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5b16af9e7d30..9918bf7441ed 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1023,13 +1023,8 @@ __buffer_unlock_commit(struct trace_buffer *buffer, struct ring_buffer_event *ev
 		ring_buffer_unlock_commit(buffer);
 }
 
-/**
- * __trace_puts - write a constant string into the trace buffer.
- * @ip:	   The address of the caller
- * @str:   The constant string to write
- * @size:  The size of the string.
- */
-int __trace_puts(unsigned long ip, const char *str, int size)
+int __trace_array_puts(struct trace_array *tr, unsigned long ip,
+		       const char *str, int size)
 {
 	struct ring_buffer_event *event;
 	struct trace_buffer *buffer;
@@ -1037,7 +1032,7 @@ int __trace_puts(unsigned long ip, const char *str, int size)
 	unsigned int trace_ctx;
 	int alloc;
 
-	if (!(global_trace.trace_flags & TRACE_ITER_PRINTK))
+	if (!(tr->trace_flags & TRACE_ITER_PRINTK))
 		return 0;
 
 	if (unlikely(tracing_selftest_running || tracing_disabled))
@@ -1046,7 +1041,7 @@ int __trace_puts(unsigned long ip, const char *str, int size)
 	alloc = sizeof(*entry) + size + 2; /* possible \n added */
 
 	trace_ctx = tracing_gen_ctx();
-	buffer = global_trace.array_buffer.buffer;
+	buffer = tr->array_buffer.buffer;
 	ring_buffer_nest_start(buffer);
 	event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, alloc,
 					    trace_ctx);
@@ -1068,11 +1063,23 @@ int __trace_puts(unsigned long ip, const char *str, int size)
 		entry->buf[size] = '\0';
 
 	__buffer_unlock_commit(buffer, event);
-	ftrace_trace_stack(&global_trace, buffer, trace_ctx, 4, NULL);
+	ftrace_trace_stack(tr, buffer, trace_ctx, 4, NULL);
  out:
 	ring_buffer_nest_end(buffer);
 	return size;
 }
+EXPORT_SYMBOL_GPL(__trace_array_puts);
+
+/**
+ * __trace_puts - write a constant string into the trace buffer.
+ * @ip:	   The address of the caller
+ * @str:   The constant string to write
+ * @size:  The size of the string.
+ */
+int __trace_puts(unsigned long ip, const char *str, int size)
+{
+	return __trace_array_puts(&global_trace, ip, str, size);
+}
 EXPORT_SYMBOL_GPL(__trace_puts);
 
 /**
-- 
2.39.1