[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20191203213019.500970064@linuxfoundation.org>
Date: Tue, 3 Dec 2019 23:34:50 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Jiri Slaby <jslaby@...e.cz>,
Thomas Gleixner <tglx@...utronix.de>,
Michal Suchanek <msuchanek@...e.de>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.3 050/135] stacktrace: Dont skip first entry on noncurrent tasks
From: Jiri Slaby <jslaby@...e.cz>
[ Upstream commit b0c51f158455e31d5024100cf3580fcd88214b0e ]
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.
Fixes: 214d8ca6ee85 ("stacktrace: Provide common infrastructure")
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Michal Suchanek <msuchanek@...e.de>
Acked-by: Josh Poimboeuf <jpoimboe@...hat.com>
Link: https://lkml.kernel.org/r/20191030072545.19462-1-jslaby@suse.cz
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
kernel/stacktrace.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c
index f5440abb75329..9bbfbdb96ae51 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);
--
2.20.1
Powered by blists - more mailing lists