[tip: core/rcu] refperf: Work around 64-bit division

[tip-bot2 for Arnd Bergmann]

The following commit has been merged into the core/rcu branch of tip:

Commit-ID:     7c944d7c67daee84e3c756bb74ad2f32b28c41cf
Gitweb:        
https://git.kernel.org/tip/7c944d7c67daee84e3c756bb74ad2f32b28c41cf
Author:        Arnd Bergmann <a...@arndb.de>
AuthorDate:    Fri, 29 May 2020 14:36:26 -07:00
Committer:     Paul E. McKenney <paul...@kernel.org>
CommitterDate: Mon, 29 Jun 2020 12:00:45 -07:00

refperf: Work around 64-bit division

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'

Fix this by using div_u64 to mark the expensive operation.

[ paulmck: Update primitive and format per Nathan Chancellor. ]
Fixes: bd5b16d6c88d ("refperf: Allow decimal nanoseconds")
Reported-by: kbuild test robot <l...@intel.com>
Reported-by: Valdis Klētnieks <valdis.kletni...@vt.edu>
Acked-by: Randy Dunlap <rdun...@infradead.org> # build-tested
Signed-off-by: Arnd Bergmann <a...@arndb.de>
Signed-off-by: Paul E. McKenney <paul...@kernel.org>
---
 kernel/rcu/refperf.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/refperf.c b/kernel/rcu/refperf.c
index 063eeb0..80d4490 100644
--- a/kernel/rcu/refperf.c
+++ b/kernel/rcu/refperf.c
@@ -478,7 +478,7 @@ 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
@@ -489,9 +489,13 @@ static int main_func(void *arg)
        strcat(buf, "Runs\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_u64_rem(result_avg[exp], 1000, &rem);
+               sprintf(buf1, "%d\t%llu.%03u\n", exp + 1, avg, rem);
                strcat(buf, buf1);
        }