Re: Re: [PATCH v2 2/3] tracing: initialize trace_seq buffers

Hi Steve,

On 25 Jan 15:44, Steven Rostedt wrote:

On Thu, 25 Jan 2024 17:16:21 -0300
"Ricardo B. Marliere" [off-list ref] wrote:

quoted

Now that trace_seq_reset have been created, correct the places where the
buffers need to be initialized.

This patch would need to come first. You don't ever want to intentionally
create a broken kernel.

Indeed, sorry for the lack of attention.

Also, the change log should be:

  In order to extend trace_seq into being dynamic, the struct trace_seq
  will no longer be valid if simply set to zero. Call trace_seq_init() for
  all trace_seq when they are first created.

Ack.

quoted

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ricardo B. Marliere <redacted>
---
 kernel/trace/trace.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

You also need to initialize iter.seq in ftrace_dump()

Thanks a lot for reviewing, I will send a v3.
-	Ricardo

-- Steve

quoted

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d4c55d3e21c2..9827700d0164 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c

@@ -4889,6 +4889,9 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot)
 
 	mutex_unlock(&trace_types_lock);
 
+	trace_seq_init(&iter->seq);
+	trace_seq_init(&iter->tmp_seq);
+
 	return iter;
 
  fail:

@@ -6770,6 +6773,7 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
 	}
 
 	trace_seq_init(&iter->seq);
+	trace_seq_init(&iter->tmp_seq);
 	iter->trace = tr->current_trace;
 
 	if (!alloc_cpumask_var(&iter->started, GFP_KERNEL)) {

@@ -6947,6 +6951,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
 	trace_iterator_reset(iter);
 	cpumask_clear(iter->started);
 	trace_seq_init(&iter->seq);
+	trace_seq_init(&iter->tmp_seq);
 
 	trace_event_read_lock();
 	trace_access_lock(iter->cpu_file);

@@ -8277,6 +8282,9 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp)
 	if (ret < 0)
 		trace_array_put(tr);
 
+	trace_seq_init(&info->iter.seq);
+	trace_seq_init(&info->iter.tmp_seq);
+
 	return ret;
 }
 

@@ -10300,6 +10308,9 @@ void trace_init_global_iter(struct trace_iterator *iter)
 	iter->temp_size = STATIC_TEMP_BUF_SIZE;
 	iter->fmt = static_fmt_buf;
 	iter->fmt_size = STATIC_FMT_BUF_SIZE;
+
+	trace_seq_init(&iter->seq);
+	trace_seq_init(&iter->tmp_seq);
 }
 
 void ftrace_dump(enum ftrace_dump_mode oops_dump_mode)

@@ -10712,6 +10723,9 @@ void __init early_trace_init(void)
 			tracepoint_printk = 0;
 		else
 			static_key_enable(&tracepoint_printk_key.key);
+
+		trace_seq_init(&tracepoint_print_iter->seq);
+		trace_seq_init(&tracepoint_print_iter->tmp_seq);
 	}
 	tracer_alloc_buffers();