linux-kernel - [PATCH RFC 03/10] perf: Simplify get_perf

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Date:   Wed,  8 Nov 2023 16:41:08 -0800
From:   Josh Poimboeuf <jpoimboe@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        Indu Bhagat <indu.bhagat@...cle.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-perf-users@...r.kernel.org, Mark Brown <broonie@...nel.org>,
        linux-toolchains@...r.kernel.org
Subject: [PATCH RFC 03/10] perf: Simplify get_perf_callchain() user logic

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

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 kernel/events/callchain.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
index aa5f9d11c28d..2bee8b6fda0e 100644
--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -202,20 +202,18 @@ get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
 
 	if (user) {
 		if (!user_mode(regs)) {
-			if  (current->mm)
-				regs = task_pt_regs(current);
-			else
-				regs = NULL;
+			if (!current->mm)
+				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);
 
-			perf_callchain_user(&ctx, regs);
-		}
+		perf_callchain_user(&ctx, regs);
 	}
 
+exit_put:
 	put_callchain_entry(rctx);
 
 	return entry;
-- 
2.41.0