Patch "tracing: Increase trace array ref count on enable and filter files" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    tracing: Increase trace array ref count on enable and filter files

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tracing-increase-trace-array-ref-count-on-enable-and.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 66f424e3596f3f04a6f7939dc01261bfd5c6401f
Author: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Date:   Wed Sep 6 22:47:12 2023 -0400

    tracing: Increase trace array ref count on enable and filter files
    
    [ Upstream commit f5ca233e2e66dc1c249bf07eefa37e34a6c9346a ]
    
    When the trace event enable and filter files are opened, increment the
    trace array ref counter, otherwise they can be accessed when the trace
    array is being deleted. The ref counter keeps the trace array from being
    deleted while those files are opened.
    
    Link: https://lkml.kernel.org/r/20230907024803.456187066@xxxxxxxxxxx
    Link: https://lore.kernel.org/all/1cb3aee2-19af-c472-e265-05176fe9bd84@xxxxxxxxxx/
    
    Cc: stable@xxxxxxxxxxxxxxx
    Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
    Cc: Mark Rutland <mark.rutland@xxxxxxx>
    Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
    Fixes: 8530dec63e7b4 ("tracing: Add tracing_check_open_get_tr()")
    Tested-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
    Tested-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
    Reported-by: Zheng Yejian <zhengyejian1@xxxxxxxxxx>
    Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f9c64329ec154..85ad403006a20 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4244,6 +4244,33 @@ int tracing_open_generic_tr(struct inode *inode, struct file *filp)
 	return 0;
 }
 
+/*
+ * The private pointer of the inode is the trace_event_file.
+ * Update the tr ref count associated to it.
+ */
+int tracing_open_file_tr(struct inode *inode, struct file *filp)
+{
+	struct trace_event_file *file = inode->i_private;
+	int ret;
+
+	ret = tracing_check_open_get_tr(file->tr);
+	if (ret)
+		return ret;
+
+	filp->private_data = inode->i_private;
+
+	return 0;
+}
+
+int tracing_release_file_tr(struct inode *inode, struct file *filp)
+{
+	struct trace_event_file *file = inode->i_private;
+
+	trace_array_put(file->tr);
+
+	return 0;
+}
+
 static int tracing_release(struct inode *inode, struct file *file)
 {
 	struct trace_array *tr = inode->i_private;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 21f85c0bd66ec..f1f54111b8561 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -680,6 +680,8 @@ void tracing_reset_all_online_cpus(void);
 void tracing_reset_all_online_cpus_unlocked(void);
 int tracing_open_generic(struct inode *inode, struct file *filp);
 int tracing_open_generic_tr(struct inode *inode, struct file *filp);
+int tracing_open_file_tr(struct inode *inode, struct file *filp);
+int tracing_release_file_tr(struct inode *inode, struct file *filp);
 bool tracing_is_disabled(void);
 bool tracer_tracing_is_on(struct trace_array *tr);
 void tracer_tracing_on(struct trace_array *tr);
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 0c21da12b650c..51adf0817ef3a 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1699,9 +1699,10 @@ static const struct file_operations ftrace_set_event_pid_fops = {
 };
 
 static const struct file_operations ftrace_enable_fops = {
-	.open = tracing_open_generic,
+	.open = tracing_open_file_tr,
 	.read = event_enable_read,
 	.write = event_enable_write,
+	.release = tracing_release_file_tr,
 	.llseek = default_llseek,
 };
 
@@ -1718,9 +1719,10 @@ static const struct file_operations ftrace_event_id_fops = {
 };
 
 static const struct file_operations ftrace_event_filter_fops = {
-	.open = tracing_open_generic,
+	.open = tracing_open_file_tr,
 	.read = event_filter_read,
 	.write = event_filter_write,
+	.release = tracing_release_file_tr,
 	.llseek = default_llseek,
 };