Commit b0c51f15 authored Oct 30, 2019 by Jiri Slaby Committed by Thomas Gleixner Nov 04, 2019

stacktrace: Don't skip first entry on noncurrent tasks



When doing cat /proc/<PID>/stack, the output is missing the first entry.
When the current code walks the stack starting in stack_trace_save_tsk,
it skips all scheduler functions (that's OK) plus one more function. But
this one function should be skipped only for the 'current' task as it is
stack_trace_save_tsk proper.

The original code (before the common infrastructure) skipped one
function only for the 'current' task -- see save_stack_trace_tsk before
3599fe12. So do so also in the new infrastructure now.

Fixes: 214d8ca6 ("stacktrace: Provide common infrastructure")
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michal Suchanek <msuchanek@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20191030072545.19462-1-jslaby@suse.cz

parent a99d8080

kernel/stacktrace.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -141,7 +141,8 @@ unsigned int stack_trace_save_tsk(struct task_struct tsk, unsigned long store,
		struct stacktrace_cookie c = {
		.store = store,
		.size = size,
		.skip = skipnr + 1,
		/* skip this function if they are tracing us */
		.skip = skipnr + !!(current == tsk),
		};

		if (!try_get_task_stack(tsk))
		@@ -298,7 +299,8 @@ unsigned int stack_trace_save_tsk(struct task_struct *task,
		struct stack_trace trace = {
		.entries = store,
		.max_entries = size,
		.skip = skipnr + 1,
		/* skip this function if they are tracing us */
		.skip = skipnr + !!(current == task),
		};

		save_stack_trace_tsk(task, &trace);