linux-kernel - [PATCH rcu 07/11] rcutorture: Make cur_ops->format_gp

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Message-Id: <20250219153938.24966-8-boqun.feng@gmail.com>
Date: Wed, 19 Feb 2025 07:39:34 -0800
From: Boqun Feng <boqun.feng@...il.com>
To: rcu@...r.kernel.org
Cc: Jonathan Corbet <corbet@....net>,	Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	"Paul E. McKenney" <paulmck@...nel.org>,
	Frederic Weisbecker <frederic@...nel.org>,
	Neeraj Upadhyay <neeraj.upadhyay@...nel.org>,
	Joel Fernandes <joel@...lfernandes.org>,
	Josh Triplett <josh@...htriplett.org>,	Boqun Feng <boqun.feng@...il.com>,
	Uladzislau Rezki <urezki@...il.com>,
	Lai Jiangshan <jiangshanlai@...il.com>,
	Zqiang <qiang.zhang1211@...il.com>,	Davidlohr Bueso <dave@...olabs.net>,
	Shuah Khan <shuah@...nel.org>,	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Huth <thuth@...hat.com>,	"Borislav Petkov (AMD)" <bp@...en8.de>,
	Ard Biesheuvel <ardb@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Josh Poimboeuf <jpoimboe@...nel.org>,	Yury Norov <yury.norov@...il.com>,
	Valentin Schneider <vschneid@...hat.com>,	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,	linux-trace-kernel@...r.kernel.org,
	linux-kselftest@...r.kernel.org
Subject: [PATCH rcu 07/11] rcutorture: Make cur_ops->format_gp_seqs take buffer length

From: "Paul E. McKenney" <paulmck@...nel.org>

The Tree and Tiny implementations of rcutorture_format_gp_seqs() use
hard-coded constants for the length of the buffer that they format into.
This is of course an accident waiting to happen, so this commit therefore
makes them take a length argument.  The rcutorture calling code uses
ARRAY_SIZE() to safely compute this new argument.

Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
Signed-off-by: Boqun Feng <boqun.feng@...il.com>
---
 kernel/rcu/rcu.h        | 2 +-
 kernel/rcu/rcutorture.c | 8 +++++---
 kernel/rcu/tiny.c       | 4 ++--
 kernel/rcu/tree.c       | 4 ++--
 4 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index 705fcbe6f500..82d8b494cc30 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -591,7 +591,7 @@ void do_trace_rcu_torture_read(const char *rcutorturename,
 static inline void rcu_gp_set_torture_wait(int duration) { }
 #endif
 unsigned long long rcutorture_gather_gp_seqs(void);
-void rcutorture_format_gp_seqs(unsigned long long seqs, char *cp);
+void rcutorture_format_gp_seqs(unsigned long long seqs, char *cp, size_t len);
 
 #ifdef CONFIG_TINY_SRCU
 
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 1fdadc1df9ad..9c9a349b9c7f 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -411,7 +411,7 @@ struct rcu_torture_ops {
 	void (*gp_slow_unregister)(atomic_t *rgssp);
 	bool (*reader_blocked)(void);
 	unsigned long long (*gather_gp_seqs)(void);
-	void (*format_gp_seqs)(unsigned long long seqs, char *cp);
+	void (*format_gp_seqs)(unsigned long long seqs, char *cp, size_t len);
 	long cbflood_max;
 	int irq_capable;
 	int can_boost;
@@ -3688,8 +3688,10 @@ rcu_torture_cleanup(void)
 				char buf2[20+1];
 				char sepchar = '-';
 
-				cur_ops->format_gp_seqs(err_segs[i].rt_gp_seq, buf1);
-				cur_ops->format_gp_seqs(err_segs[i].rt_gp_seq_end, buf2);
+				cur_ops->format_gp_seqs(err_segs[i].rt_gp_seq,
+							buf1, ARRAY_SIZE(buf1));
+				cur_ops->format_gp_seqs(err_segs[i].rt_gp_seq_end,
+							buf2, ARRAY_SIZE(buf2));
 				if (err_segs[i].rt_gp_seq == err_segs[i].rt_gp_seq_end) {
 					if (buf2[0]) {
 						for (j = 0; buf2[j]; j++)
diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index 8cbec3401184..8a52aca686a5 100644
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -264,9 +264,9 @@ unsigned long long rcutorture_gather_gp_seqs(void)
 }
 EXPORT_SYMBOL_GPL(rcutorture_gather_gp_seqs);
 
-void rcutorture_format_gp_seqs(unsigned long long seqs, char *cp)
+void rcutorture_format_gp_seqs(unsigned long long seqs, char *cp, size_t len)
 {
-	snprintf(cp, 8, "g%04llx", seqs & 0xffffULL);
+	snprintf(cp, len, "g%04llx", seqs & 0xffffULL);
 }
 EXPORT_SYMBOL_GPL(rcutorture_format_gp_seqs);
 #endif
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 83cba3d2cc48..bb061e5870c3 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -548,13 +548,13 @@ unsigned long long rcutorture_gather_gp_seqs(void)
 EXPORT_SYMBOL_GPL(rcutorture_gather_gp_seqs);
 
 /* Format grace-period sequence numbers for rcutorture diagnostics. */
-void rcutorture_format_gp_seqs(unsigned long long seqs, char *cp)
+void rcutorture_format_gp_seqs(unsigned long long seqs, char *cp, size_t len)
 {
 	unsigned int egp = (seqs >> 16) & 0xffffffULL;
 	unsigned int ggp = (seqs >> 40) & 0xffffULL;
 	unsigned int pgp = seqs & 0xffffULL;
 
-	snprintf(cp, 20, "g%04x:e%06x:p%04x", ggp, egp, pgp);
+	snprintf(cp, len, "g%04x:e%06x:p%04x", ggp, egp, pgp);
 }
 EXPORT_SYMBOL_GPL(rcutorture_format_gp_seqs);
 
-- 
2.39.5 (Apple Git-154)