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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
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6
kernel/trace/trace_stack.c
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@@ -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);