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From: Peter Zijlstra <peterz@infradead.org>
To: mingo@kernel.org
Cc: will@kernel.org, peterz@infradead.org, boqun.feng@gmail.com,
	mark.rutland@arm.com, tglx@linutronix.de, mingo@redhat.com,
	bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org,
	hpa@zytor.com, seanjc@google.com, pbonzini@redhat.com,
	jgross@suse.com, srivatsa@csail.mit.edu, amakhalov@vmware.com,
	pv-drivers@vmware.com, wanpengli@tencent.com,
	vkuznets@redhat.com, boris.ostrovsky@oracle.com,
	rafael@kernel.org, daniel.lezcano@linaro.org,
	lpieralisi@kernel.org, frederic@kernel.org, paulmck@kernel.org,
	rostedt@goodmis.org, mhiramat@kernel.org, longman@redhat.com,
	juri.lelli@redhat.com, vincent.guittot@linaro.org,
	dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de,
	bristot@redhat.com, vschneid@redhat.com,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	linux-pm@vger.kernel.org, linux-trace-kernel@vger.kernel.org
Subject: [PATCH v2 3/9] tracing: Warn about !rcu_is_watching()
Date: Thu, 26 Jan 2023 16:08:32 +0100	[thread overview]
Message-ID: <20230126151323.466670589@infradead.org> (raw)
In-Reply-To: 20230126150829.087606759@infradead.org

When using noinstr, WARN when tracing hits when RCU is disabled.

Suggested-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 include/linux/trace_recursion.h |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

--- a/include/linux/trace_recursion.h
+++ b/include/linux/trace_recursion.h
@@ -135,6 +135,21 @@ extern void ftrace_record_recursion(unsi
 # define do_ftrace_record_recursion(ip, pip)	do { } while (0)
 #endif
 
+#ifdef CONFIG_ARCH_WANTS_NO_INSTR
+# define trace_warn_on_no_rcu(ip)					\
+	({								\
+		bool __ret = !rcu_is_watching();			\
+		if (__ret && !trace_recursion_test(TRACE_RECORD_RECURSION_BIT)) { \
+			trace_recursion_set(TRACE_RECORD_RECURSION_BIT); \
+			WARN_ONCE(true, "RCU not on for: %pS\n", (void *)ip); \
+			trace_recursion_clear(TRACE_RECORD_RECURSION_BIT); \
+		}							\
+		__ret;							\
+	})
+#else
+# define trace_warn_on_no_rcu(ip)	false
+#endif
+
 /*
  * Preemption is promised to be disabled when return bit >= 0.
  */
@@ -144,6 +159,9 @@ static __always_inline int trace_test_an
 	unsigned int val = READ_ONCE(current->trace_recursion);
 	int bit;
 
+	if (trace_warn_on_no_rcu(ip))
+		return -1;
+
 	bit = trace_get_context_bit() + start;
 	if (unlikely(val & (1 << bit))) {
 		/*



WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: mingo@kernel.org
Cc: mark.rutland@arm.com, juri.lelli@redhat.com,
	daniel.lezcano@linaro.org, wanpengli@tencent.com,
	kvm@vger.kernel.org, rafael@kernel.org, peterz@infradead.org,
	lpieralisi@kernel.org, dave.hansen@linux.intel.com,
	virtualization@lists.linux-foundation.org, bsegall@google.com,
	amakhalov@vmware.com, will@kernel.org, tglx@linutronix.de,
	vschneid@redhat.com, hpa@zytor.com, x86@kernel.org,
	pv-drivers@vmware.com, mingo@redhat.com, mgorman@suse.de,
	longman@redhat.com, frederic@kernel.org,
	linux-trace-kernel@vger.kernel.org, paulmck@kernel.org,
	linux-pm@vger.kernel.org, boqun.feng@gmail.com,
	rostedt@goodmis.org, bp@alien8.de, vincent.guittot@linaro.org,
	boris.ostrovsky@oracle.com, dietmar.eggemann@arm.com,
	jgross@suse.com, seanjc@google.com, linux-kernel@vger.kernel.org,
	mhiramat@kernel.org, pbonzini@redhat.com, bristot@redhat.com
Subject: [PATCH v2 3/9] tracing: Warn about !rcu_is_watching()
Date: Thu, 26 Jan 2023 16:08:32 +0100	[thread overview]
Message-ID: <20230126151323.466670589@infradead.org> (raw)
In-Reply-To: 20230126150829.087606759@infradead.org

When using noinstr, WARN when tracing hits when RCU is disabled.

Suggested-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 include/linux/trace_recursion.h |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

--- a/include/linux/trace_recursion.h
+++ b/include/linux/trace_recursion.h
@@ -135,6 +135,21 @@ extern void ftrace_record_recursion(unsi
 # define do_ftrace_record_recursion(ip, pip)	do { } while (0)
 #endif
 
+#ifdef CONFIG_ARCH_WANTS_NO_INSTR
+# define trace_warn_on_no_rcu(ip)					\
+	({								\
+		bool __ret = !rcu_is_watching();			\
+		if (__ret && !trace_recursion_test(TRACE_RECORD_RECURSION_BIT)) { \
+			trace_recursion_set(TRACE_RECORD_RECURSION_BIT); \
+			WARN_ONCE(true, "RCU not on for: %pS\n", (void *)ip); \
+			trace_recursion_clear(TRACE_RECORD_RECURSION_BIT); \
+		}							\
+		__ret;							\
+	})
+#else
+# define trace_warn_on_no_rcu(ip)	false
+#endif
+
 /*
  * Preemption is promised to be disabled when return bit >= 0.
  */
@@ -144,6 +159,9 @@ static __always_inline int trace_test_an
 	unsigned int val = READ_ONCE(current->trace_recursion);
 	int bit;
 
+	if (trace_warn_on_no_rcu(ip))
+		return -1;
+
 	bit = trace_get_context_bit() + start;
 	if (unlikely(val & (1 << bit))) {
 		/*


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Virtualization@lists.linux-foundation.org
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  parent reply	other threads:[~2023-01-26 15:16 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-26 15:08 [PATCH v2 0/9] A few more cpuidle vs rcu fixes Peter Zijlstra
2023-01-26 15:08 ` Peter Zijlstra
2023-01-26 15:08 ` [PATCH v2 1/9] drivers: firmware: psci: Dont instrument suspend code Peter Zijlstra
2023-01-26 15:08   ` Peter Zijlstra
2023-01-31 14:22   ` [tip: sched/core] cpuidle: " tip-bot2 for Mark Rutland
2023-01-26 15:08 ` [PATCH v2 2/9] bug: Disable rcu_is_watching() during WARN/BUG Peter Zijlstra
2023-01-26 15:08   ` Peter Zijlstra
2023-01-31 14:22   ` [tip: sched/core] cpuidle: lib/bug: " tip-bot2 for Peter Zijlstra
2023-01-26 15:08 ` Peter Zijlstra [this message]
2023-01-26 15:08   ` [PATCH v2 3/9] tracing: Warn about !rcu_is_watching() Peter Zijlstra
2023-01-31 14:22   ` [tip: sched/core] cpuidle: " tip-bot2 for Peter Zijlstra
2023-01-26 15:08 ` [PATCH v2 4/9] tracing, preempt: Squash _rcuidle tracing Peter Zijlstra
2023-01-26 15:08   ` Peter Zijlstra
2023-01-31  8:50   ` [PATCH v2.1 " Peter Zijlstra
2023-01-31  8:50     ` Peter Zijlstra
2023-01-26 15:08 ` [PATCH v2 5/9] x86: Always inline arch_atomic64 Peter Zijlstra
2023-01-26 15:08   ` Peter Zijlstra
2023-01-31 14:22   ` [tip: sched/core] x86/atomics: Always inline arch_atomic64*() tip-bot2 for Peter Zijlstra
2023-01-26 15:08 ` [PATCH v2 6/9] x86/pvclock: improve atomic update of last_value in pvclock_clocksource_read Peter Zijlstra
2023-01-26 15:08   ` Peter Zijlstra
2023-01-26 15:08 ` [PATCH v2 7/9] x86: Mark sched_clock() noinstr Peter Zijlstra
2023-01-26 15:08   ` Peter Zijlstra
2023-01-31 14:22   ` [tip: sched/core] sched/clock/x86: " tip-bot2 for Peter Zijlstra
2023-01-26 15:08 ` [PATCH v2 8/9] sched/clock: Make local_clock() noinstr Peter Zijlstra
2023-01-26 15:08   ` Peter Zijlstra
2023-01-31 14:22   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2023-01-26 15:08 ` [PATCH v2 9/9] cpuidle: Fix poll_idle() noinstr annotation Peter Zijlstra
2023-01-26 15:08   ` Peter Zijlstra
2023-01-29 23:23 ` [PATCH v2 0/9] A few more cpuidle vs rcu fixes Paul E. McKenney

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