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

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@goodmis.org
Link: https://lore.kernel.org/all/1cb3aee2-19af-c472-e265-05176fe9bd84@huawei.com/
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: 8530dec63e7b4 ("tracing: Add tracing_check_open_get_tr()")
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Reported-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 35783a7baf151cf7f3c7eb65cbf228bba433fe97..0827037ee3b8175f3accc98de38c1fc2239893fa 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4973,6 +4973,33 @@ 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_mark_open(struct inode *inode, struct file *filp)
 {
        stream_open(inode, filp);

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 5669dd1f90d9e828dacaa2f53e2b2259fc2ac1e0..77debe53f07cf5663f8421214c613505a584a314 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -610,6 +610,8 @@ 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 ed367d713be07bca5e002cd5cb940b8d1a755480..2af92177b76589a1dacf398a187cbe3e6317076f 100644 (file)
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -2103,9 +2103,10 @@ static const struct file_operations ftrace_set_event_notrace_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,
 };
 
@@ -2122,9 +2123,10 @@ 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,
 };