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From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
	bpf@vger.kernel.org, x86@kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Josh Poimboeuf <jpoimboe@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>
Subject: [PATCH v8 17/18] perf: Simplify get_perf_callchain() user logic
Date: Fri, 09 May 2025 12:45:41 -0400	[thread overview]
Message-ID: <20250509165156.474492361@goodmis.org> (raw)
In-Reply-To: 20250509164524.448387100@goodmis.org

From: Josh Poimboeuf <jpoimboe@kernel.org>

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

Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 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



  parent reply	other threads:[~2025-05-09 16:51 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-05-09 16:45 [PATCH v8 00/18] unwind_user: perf: x86: Deferred unwinding infrastructure Steven Rostedt
2025-05-09 16:45 ` [PATCH v8 01/18] unwind_user: Add user space unwinding API Steven Rostedt
2025-05-09 16:45 ` [PATCH v8 02/18] unwind_user: Add frame pointer support Steven Rostedt
2025-05-09 16:45 ` [PATCH v8 03/18] unwind_user/x86: Enable frame pointer unwinding on x86 Steven Rostedt
2025-05-09 16:45 ` [PATCH v8 04/18] perf/x86: Rename and move get_segment_base() and make it global Steven Rostedt
2025-05-09 16:45 ` [PATCH v8 05/18] unwind_user: Add compat mode frame pointer support Steven Rostedt
2025-05-09 16:45 ` [PATCH v8 06/18] unwind_user/x86: Enable compat mode frame pointer unwinding on x86 Steven Rostedt
2025-05-09 16:45 ` [PATCH v8 07/18] unwind_user/deferred: Add unwind_deferred_trace() Steven Rostedt
2025-05-09 16:45 ` [PATCH v8 08/18] unwind_user/deferred: Add unwind cache Steven Rostedt
2025-05-09 16:45 ` [PATCH v8 09/18] unwind_user/deferred: Add deferred unwinding interface Steven Rostedt
2025-05-09 16:45 ` [PATCH v8 10/18] unwind_user/deferred: Make unwind deferral requests NMI-safe Steven Rostedt
2025-05-09 16:45 ` [PATCH v8 11/18] unwind deferred: Use bitmask to determine which callbacks to call Steven Rostedt
2025-05-09 16:45 ` [PATCH v8 12/18] unwind deferred: Use SRCU unwind_deferred_task_work() Steven Rostedt
2025-05-09 21:49   ` Andrii Nakryiko
2025-05-10 13:41     ` Steven Rostedt
2025-05-12 16:17       ` Andrii Nakryiko
2025-05-09 16:45 ` [PATCH v8 13/18] unwind: Clear unwind_mask on exit back to user space Steven Rostedt
2025-05-09 16:45 ` [PATCH v8 14/18] perf: Remove get_perf_callchain() init_nr argument Steven Rostedt
2025-05-09 17:11   ` Alexei Starovoitov
2025-05-09 16:45 ` [PATCH v8 15/18] perf: Have get_perf_callchain() return NULL if crosstask and user are set Steven Rostedt
2025-05-09 21:53   ` Andrii Nakryiko
2025-05-10 13:46     ` Steven Rostedt
2025-05-10 17:59     ` Josh Poimboeuf
2025-05-12 22:27       ` Andrii Nakryiko
2025-05-09 16:45 ` [PATCH v8 16/18] perf: Use current->flags & PF_KTHREAD instead of current->mm == NULL Steven Rostedt
2025-05-09 16:45 ` Steven Rostedt [this message]
2025-05-09 16:45 ` [PATCH v8 18/18] perf: Skip user unwind if the task is a kernel thread Steven Rostedt

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