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From: Steven Rostedt <rostedt@kernel.org>
To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
	linux-perf-users@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	"Liang, Kan" <kan.liang@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Josh Poimboeuf <jpoimboe@kernel.org>
Subject: [RESEND][PATCH 4/5] perf: Simplify get_perf_callchain() user logic
Date: Wed, 20 Aug 2025 14:03:42 -0400	[thread overview]
Message-ID: <20250820180428.760066227@kernel.org> (raw)
In-Reply-To: 20250820180338.701352023@kernel.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 5982d18f169b..808c0d7a31fa 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 && !crosstask) {
 		if (!user_mode(regs)) {
 			if (current->flags & (PF_KTHREAD | PF_USER_WORKER))
-				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;
-- 
2.50.1



  parent reply	other threads:[~2025-08-20 18:04 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-20 18:03 [RESEND][PATCH 0/5] perf: Clean ups and simplifications Steven Rostedt
2025-08-20 18:03 ` [RESEND][PATCH 1/5] perf: Remove get_perf_callchain() init_nr argument Steven Rostedt
2025-08-20 18:03 ` [RESEND][PATCH 2/5] perf: Have get_perf_callchain() return NULL if crosstask and user are set Steven Rostedt
2025-08-20 18:03 ` [RESEND][PATCH 3/5] perf: Use current->flags & PF_KTHREAD|PF_USER_WORKER instead of current->mm == NULL Steven Rostedt
2025-08-20 18:03 ` Steven Rostedt [this message]
2025-08-20 18:03 ` [RESEND][PATCH 5/5] perf: Skip user unwind if the task is a kernel thread Steven Rostedt
2025-08-25 11:12 ` [RESEND][PATCH 0/5] perf: Clean ups and simplifications Peter Zijlstra

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