[PATCH v6 12/18] perf: Simplify get_perf_callchain() user logic

[Steven Rostedt]

From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

Simplify the get_perf_callchain() user logic a bit.  task_pt_regs()
should never be NULL.

Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
Changes since v5: https://lore.kernel.org/20250424162633.048002581@xxxxxxxxxxx

- Use (current->flags & PF_KTHREAD) instead of current->mm == NULL to
  determine if a task is a kernel thread or not (Peter Zijlstra)

 kernel/events/callchain.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
index cda145dc11bd..2798c0c9f782 100644
--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -247,21 +247,19 @@ get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
 	if (user) {
 		if (!user_mode(regs)) {
 			if (current->flags & PF_KTHREAD)
-				regs = NULL;
-			else
-				regs = task_pt_regs(current);
+				goto exit_put;
+			regs = task_pt_regs(current);
 		}
 
-		if (regs) {
-			if (add_mark)
-				perf_callchain_store_context(&ctx, PERF_CONTEXT_USER);
+		if (add_mark)
+			perf_callchain_store_context(&ctx, PERF_CONTEXT_USER);
 
-			start_entry_idx = entry->nr;
-			perf_callchain_user(&ctx, regs);
-			fixup_uretprobe_trampoline_entries(entry, start_entry_idx);
-		}
+		start_entry_idx = entry->nr;
+		perf_callchain_user(&ctx, regs);
+		fixup_uretprobe_trampoline_entries(entry, start_entry_idx);
 	}
 
+exit_put:
 	put_callchain_entry(rctx);
 
 	return entry;
-- 
2.47.2