[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20191030072545.19462-1-jslaby@suse.cz>
Date: Wed, 30 Oct 2019 08:25:45 +0100
From: Jiri Slaby <jslaby@...e.cz>
To: tglx@...utronix.de
Cc: linux-kernel@...r.kernel.org, Jiri Slaby <jslaby@...e.cz>,
Michal Suchanek <msuchanek@...e.de>,
Josh Poimboeuf <jpoimboe@...hat.com>
Subject: [PATCH v3] 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
3599fe12a125. So do so also in the new infrastructure now.
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Fixes: 214d8ca6ee85 ("stacktrace: Provide common infrastructure")
Tested-by: Michal Suchanek <msuchanek@...e.de>
Acked-by: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
---
Notes:
[v2] add the same for the !ARCH_STACKWALK case
[v3] fix build on !ARCH_STACKWALK
kernel/stacktrace.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c
index 6d1f68b7e528..c9ea7eb2cb1a 100644
--- a/kernel/stacktrace.c
+++ b/kernel/stacktrace.c
@@ -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);
--
2.23.0
Powered by blists - more mailing lists