linux-kernel - [tip: core/rcu] refperf: Dynamically allocate thread-summary output buffer

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Date:   Fri, 31 Jul 2020 09:23:03 -0000
From:   "tip-bot2 for Paul E. McKenney" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        "Paul E. McKenney" <paulmck@...nel.org>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: core/rcu] refperf: Dynamically allocate thread-summary output buffer

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

Commit-ID:     2e90de76f226f11fe26c871aa321be28152f565a
Gitweb:        https://git.kernel.org/tip/2e90de76f226f11fe26c871aa321be28152f565a
Author:        Paul E. McKenney <paulmck@...nel.org>
AuthorDate:    Mon, 25 May 2020 17:45:03 -07:00
Committer:     Paul E. McKenney <paulmck@...nel.org>
CommitterDate: Mon, 29 Jun 2020 12:00:44 -07:00

refperf: Dynamically allocate thread-summary output buffer

Currently, the buffer used to accumulate the thread-summary output is
fixed size, which will cause problems if someone decides to run on a large
number of PCUs.  This commit therefore dynamically allocates this buffer.

[ paulmck: Fix memory allocation as suggested by KASAN. ]
Cc: Joel Fernandes (Google) <joel@...lfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 kernel/rcu/refperf.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/rcu/refperf.c b/kernel/rcu/refperf.c
index 75b9cce..fc940e3 100644
--- a/kernel/rcu/refperf.c
+++ b/kernel/rcu/refperf.c
@@ -301,9 +301,12 @@ u64 process_durations(int n)
 	int i;
 	struct reader_task *rt;
 	char buf1[64];
-	char buf[512];
+	char *buf;
 	u64 sum = 0;
 
+	buf = kmalloc(128 + nreaders * 32, GFP_KERNEL);
+	if (!buf)
+		return 0;
 	buf[0] = 0;
 	sprintf(buf, "Experiment #%d (Format: <THREAD-NUM>:<Total loop time in ns>)",
 		exp_idx);
@@ -322,6 +325,7 @@ u64 process_durations(int n)
 
 	PERFOUT("%s\n", buf);
 
+	kfree(buf);
 	return sum;
 }