From: Arnd Bergmann <arnd@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mark Rutland <mark.rutland@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org
Subject: [PATCH] ftrace: sample: avoid open-coded 64-bit division
Date: Mon, 30 Jan 2023 14:02:37 +0100 [thread overview]
Message-ID: <20230130130246.247537-1-arnd@kernel.org> (raw)
From: Arnd Bergmann <arnd@arndb.de>
Calculating the average period requires a 64-bit division that leads
to a link failure on 32-bit architectures:
x86_64-linux-ld: samples/ftrace/ftrace-ops.o: in function `ftrace_ops_sample_init':
ftrace-ops.c:(.init.text+0x23b): undefined reference to `__udivdi3'
Use the div_u64() helper to do this instead. Since this is an init function that
is not called frequently, the runtime overhead is going to be acceptable.
Fixes: b56c68f705ca ("ftrace: Add sample with custom ops")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
samples/ftrace/ftrace-ops.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/samples/ftrace/ftrace-ops.c b/samples/ftrace/ftrace-ops.c
index 24deb51c7261..0c8da87ff5c3 100644
--- a/samples/ftrace/ftrace-ops.c
+++ b/samples/ftrace/ftrace-ops.c
@@ -223,7 +223,7 @@ static int __init ftrace_ops_sample_init(void)
pr_info("Attempted %u calls to %ps in %lluns (%lluns / call)\n",
nr_function_calls, tracee_relevant,
- period, period / nr_function_calls);
+ period, div_u64(period, nr_function_calls));
if (persist)
return 0;
--
2.39.0
next reply other threads:[~2023-01-30 13:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-30 13:02 Arnd Bergmann [this message]
2023-01-30 13:07 ` [PATCH] ftrace: sample: avoid open-coded 64-bit division Mark Rutland
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