On Fri, 28 Aug 2026 14:04:11 -0400
Steven Rostedt <[email protected]> wrote:
> I guess the issue is that the ops may be freed before you get access to the
> trace array. Anyway more needs to be changed. I may remove the extra
> reference. No need to do it twice. Also since trace_stack may have the
> issue too.
Something more like this:
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 02bc5027523a..bd76a16a63af 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -866,8 +866,9 @@ unsigned long ftrace_get_addr_new(struct dyn_ftrace *rec);
unsigned long ftrace_get_addr_curr(struct dyn_ftrace *rec);
extern ftrace_func_t ftrace_trace_function;
+struct trace_array;
-int ftrace_regex_open(struct ftrace_ops *ops, int flag,
+int ftrace_regex_open(struct trace_array *tr, struct ftrace_ops *ops, int flag,
struct inode *inode, struct file *file);
ssize_t ftrace_filter_write(struct file *file, const char __user *ubuf,
size_t cnt, loff_t *ppos);
@@ -1077,7 +1078,7 @@ static inline unsigned long ftrace_location(unsigned long
ip)
* have them defined when ftrace is not enabled, but these
* functions may still be called. Use a macro instead of inline.
*/
-#define ftrace_regex_open(ops, flag, inod, file) ({ -ENODEV; })
+#define ftrace_regex_open(tr, ops, flag, inode, file) ({ -ENODEV; })
#define ftrace_set_early_filter(ops, buf, enable) do { } while (0)
#define ftrace_set_filter_ip(ops, ip, remove, reset) ({ -ENODEV; })
#define ftrace_set_filter_ips(ops, ips, cnt, remove, reset) ({ -ENODEV; })
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f9d80c7bd9f1..fa7c7186c02f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4677,6 +4677,7 @@ ftrace_avail_addrs_open(struct inode *inode, struct file
*file)
/**
* ftrace_regex_open - initialize function tracer filter files
+ * @tr: The trace_array that holds the ftrace_ops [optional]
* @ops: The ftrace_ops that hold the hash filters
* @flag: The type of filter to process
* @inode: The inode, usually passed in to your open routine
@@ -4694,23 +4695,29 @@ ftrace_avail_addrs_open(struct inode *inode, struct
file *file)
* Returns: 0 on success or a negative errno value on failure
*/
int
-ftrace_regex_open(struct ftrace_ops *ops, int flag,
+ftrace_regex_open(struct trace_array *tr, struct ftrace_ops *ops, int flag,
struct inode *inode, struct file *file)
{
- struct ftrace_iterator *iter;
+ struct ftrace_iterator *iter = NULL;
struct ftrace_hash *hash;
struct list_head *mod_head;
- struct trace_array *tr = ops->private;
- int ret = -ENOMEM;
-
- ftrace_ops_init(ops);
+ int ret = -ENODEV;
if (unlikely(ftrace_disabled))
return -ENODEV;
- if (tracing_check_open_get_tr(tr))
+ if (tr && tracing_check_open_get_tr(tr))
return -ENODEV;
+ if (!ops)
+ ops = tr ? tr->ops : &global_ops;
+
+ if (WARN_ON_ONCE(!ops))
+ goto out;
+
+ ftrace_ops_init(ops);
+
+ ret = -ENOMEM;
iter = kzalloc_obj(*iter);
if (!iter)
goto out;
@@ -4788,21 +4795,19 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag,
static int
ftrace_filter_open(struct inode *inode, struct file *file)
{
- struct ftrace_ops *ops = inode->i_private;
+ struct trace_array *tr = inode->i_private;
- /* Checks for tracefs lockdown */
- return ftrace_regex_open(ops,
- FTRACE_ITER_FILTER | FTRACE_ITER_DO_PROBES,
- inode, file);
+ return ftrace_regex_open(tr, NULL,
+ FTRACE_ITER_FILTER | FTRACE_ITER_DO_PROBES,
+ inode, file);
}
static int
ftrace_notrace_open(struct inode *inode, struct file *file)
{
- struct ftrace_ops *ops = inode->i_private;
+ struct trace_array *tr = inode->i_private;
- /* Checks for tracefs lockdown */
- return ftrace_regex_open(ops, FTRACE_ITER_NOTRACE,
+ return ftrace_regex_open(tr, NULL, FTRACE_ITER_NOTRACE,
inode, file);
}
@@ -7492,15 +7497,15 @@ static const struct file_operations
ftrace_graph_notrace_fops = {
};
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
-void ftrace_create_filter_files(struct ftrace_ops *ops,
+void ftrace_create_filter_files(struct trace_array *tr,
struct dentry *parent)
{
trace_create_file("set_ftrace_filter", TRACE_MODE_WRITE, parent,
- ops, &ftrace_filter_fops);
+ tr, &ftrace_filter_fops);
trace_create_file("set_ftrace_notrace", TRACE_MODE_WRITE, parent,
- ops, &ftrace_notrace_fops);
+ tr, &ftrace_notrace_fops);
}
/*
@@ -7525,7 +7530,6 @@ void ftrace_destroy_filter_files(struct ftrace_ops *ops)
static __init int ftrace_init_dyn_tracefs(struct dentry *d_tracer)
{
-
trace_create_file("available_filter_functions", TRACE_MODE_READ,
d_tracer, NULL, &ftrace_avail_fops);
@@ -7538,7 +7542,7 @@ static __init int ftrace_init_dyn_tracefs(struct dentry
*d_tracer)
trace_create_file("touched_functions", TRACE_MODE_READ,
d_tracer, NULL, &ftrace_touched_fops);
- ftrace_create_filter_files(&global_ops, d_tracer);
+ ftrace_create_filter_files(NULL, d_tracer);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
trace_create_file("set_graph_function", TRACE_MODE_WRITE, d_tracer,
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 74a7a50d1e78..3c111ca88e32 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1340,7 +1340,7 @@ extern void clear_ftrace_function_probes(struct
trace_array *tr);
int register_ftrace_command(struct ftrace_func_command *cmd);
int unregister_ftrace_command(struct ftrace_func_command *cmd);
-void ftrace_create_filter_files(struct ftrace_ops *ops,
+void ftrace_create_filter_files(struct trace_array *tr,
struct dentry *parent);
void ftrace_destroy_filter_files(struct ftrace_ops *ops);
@@ -1363,11 +1363,12 @@ static inline void clear_ftrace_function_probes(struct
trace_array *tr)
{
}
+static inline void ftrace_create_filter_files(struct trace_array *tr,
+ struct dentry *parent) { }
/*
* The ops parameter passed in is usually undefined.
* This must be a macro.
*/
-#define ftrace_create_filter_files(ops, parent) do { } while (0)
#define ftrace_destroy_filter_files(ops) do { } while (0)
#endif /* CONFIG_FUNCTION_TRACER && CONFIG_DYNAMIC_FTRACE */
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index cd37f2013758..c879d43a5fbb 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -101,7 +101,7 @@ int ftrace_create_function_files(struct trace_array *tr,
return ret;
}
- ftrace_create_filter_files(tr->ops, parent);
+ ftrace_create_filter_files(tr, parent);
return 0;
}
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index 0aa2514a6593..e7f4e523587d 100644
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -499,7 +499,7 @@ stack_trace_filter_open(struct inode *inode, struct file
*file)
struct ftrace_ops *ops = inode->i_private;
/* Checks for tracefs lockdown */
- return ftrace_regex_open(ops, FTRACE_ITER_FILTER,
+ return ftrace_regex_open(NULL, ops, FTRACE_ITER_FILTER,
inode, file);
}
--
2.53.0
-- Steve
