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ftrace: Fix regression with module command in stack_trace_filter

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When doing the following command:

 # echo ":mod:kvm_intel" > /sys/kernel/tracing/stack_trace_filter

it triggered a crash.

This happened with the clean up of probes. It required all callers to the
regex function (doing ftrace filtering) to have ops->private be a pointer to
a trace_array. But for the stack tracer, that is not the case.

Allow for the ops->private to be NULL, and change the function command
callbacks to handle the trace_array pointer being NULL as well.

Fixes: d2afd57a4b ("tracing/ftrace: Allow instances to have their own function probes")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware) 2017-06-29 10:05:45 -04:00
parent 32c1431eea
commit 0f17976568
4 changed files with 19 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
kernel/trace/ftrace.c
View File

@ -4337,9 +4337,6 @@ static int ftrace_process_regex(struct ftrace_iterator *iter,
command = strsep(&next, ":");
if (WARN_ON_ONCE(!tr))
return -EINVAL;
mutex_lock(&ftrace_cmd_mutex);
list_for_each_entry(p, &ftrace_commands, list) {
if (strcmp(p->name, command) == 0) {

3
kernel/trace/trace.c
View File

@ -6881,6 +6881,9 @@ ftrace_trace_snapshot_callback(struct trace_array *tr, struct ftrace_hash *hash,
char *number;
int ret;
if (!tr)
return -ENODEV;
/* hash funcs only work with set_ftrace_filter */
if (!enable)
return -EINVAL;

12
kernel/trace/trace_functions.c
View File

@ -654,6 +654,9 @@ ftrace_trace_onoff_callback(struct trace_array *tr, struct ftrace_hash *hash,
{
struct ftrace_probe_ops *ops;
if (!tr)
return -ENODEV;
/* we register both traceon and traceoff to this callback */
if (strcmp(cmd, "traceon") == 0)
ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
@ -670,6 +673,9 @@ ftrace_stacktrace_callback(struct trace_array *tr, struct ftrace_hash *hash,
{
struct ftrace_probe_ops *ops;
if (!tr)
return -ENODEV;
ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;
return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
@ -682,6 +688,9 @@ ftrace_dump_callback(struct trace_array *tr, struct ftrace_hash *hash,
{
struct ftrace_probe_ops *ops;
if (!tr)
return -ENODEV;
ops = &dump_probe_ops;
/* Only dump once. */
@ -695,6 +704,9 @@ ftrace_cpudump_callback(struct trace_array *tr, struct ftrace_hash *hash,
{
struct ftrace_probe_ops *ops;
if (!tr)
return -ENODEV;
ops = &cpudump_probe_ops;
/* Only dump once. */

6
kernel/trace/trace_stack.c
View File

@ -409,7 +409,9 @@ static const struct file_operations stack_trace_fops = {
static int
stack_trace_filter_open(struct inode *inode, struct file *file)
{
return ftrace_regex_open(&trace_ops, FTRACE_ITER_FILTER,
struct ftrace_ops *ops = inode->i_private;
return ftrace_regex_open(ops, FTRACE_ITER_FILTER,
inode, file);
}
@ -476,7 +478,7 @@ static __init int stack_trace_init(void)
NULL, &stack_trace_fops);
trace_create_file("stack_trace_filter", 0444, d_tracer,
NULL, &stack_trace_filter_fops);
&trace_ops, &stack_trace_filter_fops);
if (stack_trace_filter_buf[0])
ftrace_set_early_filter(&trace_ops, stack_trace_filter_buf, 1);