[PATCH] refperf: work around 64-bit division

From: Arnd Bergmann <arnd@arndb.de>
To: "Paul E. McKenney" <paulmck@kernel.org>,
	Josh Triplett <josh@joshtriplett.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
	"Joel Fernandes (Google)" <joel@joelfernandes.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	rcu@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] refperf: work around 64-bit division
Date: Fri, 29 May 2020 22:15:51 +0200	[thread overview]
Message-ID: <20200529201600.493808-1-arnd@arndb.de> (raw)

A 64-bit division was introduced in refperf, breaking compilation
on all 32-bit architectures:

kernel/rcu/refperf.o: in function `main_func':
refperf.c:(.text+0x57c): undefined reference to `__aeabi_uldivmod'

Work it by using div_u64 to mark the expensive operation.

Fixes: bd5b16d6c88d ("refperf: Allow decimal nanoseconds")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 kernel/rcu/refperf.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/refperf.c b/kernel/rcu/refperf.c
index 47df72c492b3..c2366648981d 100644
--- a/kernel/rcu/refperf.c
+++ b/kernel/rcu/refperf.c
@@ -386,7 +386,7 @@ static int main_func(void *arg)
 		if (torture_must_stop())
 			goto end;
 
-		result_avg[exp] = 1000 * process_durations(nreaders) / (nreaders * loops);
+		result_avg[exp] = div_u64(1000 * process_durations(nreaders), nreaders * loops);
 	}
 
 	// Print the average of all experiments
@@ -397,9 +397,14 @@ static int main_func(void *arg)
 	strcat(buf, "Threads\tTime(ns)\n");
 
 	for (exp = 0; exp < nruns; exp++) {
+		u64 avg;
+		u32 rem;
+
 		if (errexit)
 			break;
-		sprintf(buf1, "%d\t%llu.%03d\n", exp + 1, result_avg[exp] / 1000, (int)(result_avg[exp] % 1000));
+
+		avg = div_s64_rem(result_avg[exp], 1000, &rem);
+		sprintf(buf1, "%d\t%llu.%03d\n", exp + 1, avg, rem);
 		strcat(buf, buf1);
 	}
 
-- 
2.26.2

