[PATCH v9 05/11] perf: Skip user unwind if the task is a kernel thread

[Steven Rostedt]

From: Josh Poimboeuf <jpoim...@kernel.org>

If the task is not a user thread, there's no user stack to unwind.

Signed-off-by: Josh Poimboeuf <jpoim...@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org>
---
 kernel/events/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 375115492c02..55d5d4ded7ab 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8144,7 +8144,8 @@ struct perf_callchain_entry *
 perf_callchain(struct perf_event *event, struct pt_regs *regs)
 {
        bool kernel = !event->attr.exclude_callchain_kernel;
-       bool user   = !event->attr.exclude_callchain_user;
+       bool user   = !event->attr.exclude_callchain_user &&
+               !(current->flags & PF_KTHREAD);
        /* Disallow cross-task user callchains. */
        bool crosstask = event->ctx->task && event->ctx->task != current;
        const u32 max_stack = event->attr.sample_max_stack;
-- 
2.47.2