Commit 9880eb87 authored by Li Zhijian's avatar Li Zhijian Committed by Paul E. McKenney
Browse files

refscale: Prevent buffer to pr_alert() being too long 



0Day/LKP observed that the refscale results fail to complete when larger
values of nrun (such as 300) are specified.  The problem is that printk()
can accept at most a 1024-byte buffer.  This commit therefore prints
the buffer whenever its length exceeds 800 bytes.

CC: Philip Li <philip.li@intel.com>
Reported-by: default avatarkernel test robot <lkp@intel.com>
Signed-off-by: default avatarLi Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent c30c8763

kernel/rcu/refscale.c

+13 −10
Original line number Diff line number Diff line
@@ -604,7 +604,7 @@ static u64 process_durations(int n) 
	char *buf;

	u64 sum = 0;



	buf = kmalloc(128 + nreaders * 32, GFP_KERNEL);

	buf = kmalloc(800 + 64, GFP_KERNEL);

	if (!buf)

		return 0;

	buf[0] = 0;
@@ -617,13 +617,15 @@ static u64 process_durations(int n) 


		if (i % 5 == 0)

			strcat(buf, "\n");

		if (strlen(buf) >= 800) {

			pr_alert("%s", buf);

			buf[0] = 0;

		}

		strcat(buf, buf1);



		sum += rt->last_duration_ns;

	}

	strcat(buf, "\n");



	SCALEOUT("%s\n", buf);

	pr_alert("%s\n", buf);



	kfree(buf);

	return sum;
@@ -647,7 +649,7 @@ static int main_func(void *arg) 


	VERBOSE_SCALEOUT("main_func task started");

	result_avg = kzalloc(nruns * sizeof(*result_avg), GFP_KERNEL);

	buf = kzalloc(64 + nruns * 32, GFP_KERNEL);

	buf = kzalloc(800 + 64, GFP_KERNEL);

	if (!result_avg || !buf) {

		VERBOSE_SCALEOUT_ERRSTRING("out of memory");

		goto oom_exit;
@@ -695,10 +697,7 @@ static int main_func(void *arg) 
	// Print the average of all experiments

	SCALEOUT("END OF TEST. Calculating average duration per loop (nanoseconds)...\n");



	buf[0] = 0;

	strcat(buf, "\n");

	strcat(buf, "Runs\tTime(ns)\n");



	pr_alert("Runs\tTime(ns)\n");

	for (exp = 0; exp < nruns; exp++) {

		u64 avg;

		u32 rem;
@@ -706,9 +705,13 @@ static int main_func(void *arg) 
		avg = div_u64_rem(result_avg[exp], 1000, &rem);

		sprintf(buf1, "%d\t%llu.%03u\n", exp + 1, avg, rem);

		strcat(buf, buf1);

		if (strlen(buf) >= 800) {

			pr_alert("%s", buf);

			buf[0] = 0;

		}

	}



	SCALEOUT("%s", buf);

	pr_alert("%s", buf);



oom_exit:

	// This will shutdown everything including us.