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authorJiri Slaby <jslaby@suse.cz>2019-10-30 08:25:45 +0100
committerThomas Gleixner <tglx@linutronix.de>2019-11-04 21:19:25 +0100
commitb0c51f158455e31d5024100cf3580fcd88214b0e (patch)
tree91ad1228a374988275c24f2c3f31063a1faa6610 /kernel/stacktrace.c
parenta99d8080aaf358d5d23581244e5da23b35e340b9 (diff)
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. Fixes: 214d8ca6ee85 ("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
Diffstat (limited to 'kernel/stacktrace.c')
-rw-r--r--kernel/stacktrace.c6
1 files 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);

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