[PATCH tip/core/rcu 10/30] refperf: Dynamically allocate experiment-summary output buffer

paulmck
2020-06-23T00:30:27Z

Currently, the buffer used to accumulate the experiment-summary output
is fixed size, which will cause problems if someone decides to run
one hundred experiments. This commit therefore dynamically allocates
this buffer.

Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/refperf.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/kernel/rcu/refperf.c b/kernel/rcu/refperf.c
index 6324449..75b9cce 100644
--- a/kernel/rcu/refperf.c
+++ b/kernel/rcu/refperf.c
@@ -333,9 +333,10 @@ u64 process_durations(int n)
// point all the timestamps are printed.
static int main_func(void *arg)
{
+ bool errexit = false;
int exp, r;
char buf1[64];
- char buf[512];
+ char *buf;
u64 *result_avg;

set_cpus_allowed_ptr(current, cpumask_of(nreaders % nr_cpu_ids));
@@ -343,8 +344,11 @@ static int main_func(void *arg)

VERBOSE_PERFOUT("main_func task started");
result_avg = kzalloc(nruns * sizeof(*result_avg), GFP_KERNEL);
- if (!result_avg)
+ buf = kzalloc(64 + nruns * 32, GFP_KERNEL);
+ if (!result_avg || !buf) {
VERBOSE_PERFOUT_ERRSTRING("out of memory");
+ errexit = true;
+ }
atomic_inc(&n_init);

// Wait for all threads to start.
@@ -354,7 +358,7 @@ static int main_func(void *arg)

// Start exp readers up per experiment
for (exp = 0; exp < nruns && !torture_must_stop(); exp++) {
- if (!result_avg)
+ if (errexit)
break;
if (torture_must_stop())
goto end;
@@ -391,13 +395,13 @@ static int main_func(void *arg)
strcat(buf, "Threads\tTime(ns)\n");

for (exp = 0; exp < nruns; exp++) {
- if (!result_avg)
+ if (errexit)
break;
sprintf(buf1, "%d\t%llu.%03d\n", exp + 1, result_avg[exp] / 1000, (int)(result_avg[exp] % 1000));
strcat(buf, buf1);
}

- if (result_avg)
+ if (!errexit)
PERFOUT("%s", buf);

// This will shutdown everything including us.
@@ -412,6 +416,8 @@ static int main_func(void *arg)

end:
torture_kthread_stopping("main_func");
+ kfree(result_avg);
+ kfree(buf);
return 0;
}

--
2.9.5