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From: Joel Fernandes <joelaf@google.com>
To: linux-kernel@vger.kernel.org
Cc: kernel-team@android.com,
	"Joel Fernandes (Google)" <joel@joelfernandes.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	Byungchul Park <byungchul.park@lge.com>,
	Erick Reyes <erickreyes@google.com>,
	Ingo Molnar <mingo@redhat.com>, Julia Cartwright <julia@ni.com>,
	linux-kselftest@vger.kernel.org,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Paul McKenney <paulmck@linux.vnet.ibm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Shuah Khan <shuah@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Thomas Glexiner <tglx@linutronix.de>,
	Todd Kjos <tkjos@google.com>,
	Tom Zanussi <tom.zanussi@linux.intel.com>
Subject: [PATCH v9 2/7] srcu: Add notrace variant of srcu_dereference
Date: Thu,  7 Jun 2018 13:38:10 -0700	[thread overview]
Message-ID: <20180607203815.255845-3-joel@joelfernandes.org> (raw)
In-Reply-To: <20180607203815.255845-1-joel@joelfernandes.org>

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

In the last patch in this series, we are making lockdep register hooks
onto the irq_{disable,enable} tracepoints. These tracepoints use the
_rcuidle tracepoint variant. In this series we switch the _rcuidle
tracepoint callers to use SRCU instead of sched-RCU. Inorder to
dereference the pointer to the probe functions, we could call
srcu_dereference, however this API will call back into lockdep to check
if the lock is held *before* the lockdep probe hooks have a chance to
run and annotate the IRQ enabled/disabled state.

For this reason we need a notrace variant of srcu_dereference since
otherwise we get lockdep splats. This patch adds the needed
srcu_dereference_notrace variant.

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
 include/linux/srcu.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 2ec618979b20..a1c4947be877 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -135,6 +135,11 @@ static inline int srcu_read_lock_held(const struct srcu_struct *sp)
  */
 #define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0)
 
+/**
+ * srcu_dereference_notrace - no tracing and no lockdep calls from here
+ */
+#define srcu_dereference_notrace(p, sp) srcu_dereference_check((p), (sp), 1)
+
 /**
  * srcu_read_lock - register a new reader for an SRCU-protected structure.
  * @sp: srcu_struct in which to register the new reader.
-- 
2.17.1.1185.g55be947832-goog

WARNING: multiple messages have this Message-ID (diff)
From: joelaf at google.com (Joel Fernandes)
Subject: [PATCH v9 2/7] srcu: Add notrace variant of srcu_dereference
Date: Thu,  7 Jun 2018 13:38:10 -0700	[thread overview]
Message-ID: <20180607203815.255845-3-joel@joelfernandes.org> (raw)
In-Reply-To: <20180607203815.255845-1-joel@joelfernandes.org>

From: "Joel Fernandes (Google)" <joel at joelfernandes.org>

In the last patch in this series, we are making lockdep register hooks
onto the irq_{disable,enable} tracepoints. These tracepoints use the
_rcuidle tracepoint variant. In this series we switch the _rcuidle
tracepoint callers to use SRCU instead of sched-RCU. Inorder to
dereference the pointer to the probe functions, we could call
srcu_dereference, however this API will call back into lockdep to check
if the lock is held *before* the lockdep probe hooks have a chance to
run and annotate the IRQ enabled/disabled state.

For this reason we need a notrace variant of srcu_dereference since
otherwise we get lockdep splats. This patch adds the needed
srcu_dereference_notrace variant.

Reviewed-by: Paul E. McKenney <paulmck at linux.vnet.ibm.com>
Signed-off-by: Joel Fernandes (Google) <joel at joelfernandes.org>
---
 include/linux/srcu.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 2ec618979b20..a1c4947be877 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -135,6 +135,11 @@ static inline int srcu_read_lock_held(const struct srcu_struct *sp)
  */
 #define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0)
 
+/**
+ * srcu_dereference_notrace - no tracing and no lockdep calls from here
+ */
+#define srcu_dereference_notrace(p, sp) srcu_dereference_check((p), (sp), 1)
+
 /**
  * srcu_read_lock - register a new reader for an SRCU-protected structure.
  * @sp: srcu_struct in which to register the new reader.
-- 
2.17.1.1185.g55be947832-goog

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WARNING: multiple messages have this Message-ID (diff)
From: joelaf@google.com (Joel Fernandes)
Subject: [PATCH v9 2/7] srcu: Add notrace variant of srcu_dereference
Date: Thu,  7 Jun 2018 13:38:10 -0700	[thread overview]
Message-ID: <20180607203815.255845-3-joel@joelfernandes.org> (raw)
Message-ID: <20180607203810.pzbTGr6cv9pxgWJChVzBWjIAczthuAlGNQNnOpyxRrk@z> (raw)
In-Reply-To: <20180607203815.255845-1-joel@joelfernandes.org>

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

In the last patch in this series, we are making lockdep register hooks
onto the irq_{disable,enable} tracepoints. These tracepoints use the
_rcuidle tracepoint variant. In this series we switch the _rcuidle
tracepoint callers to use SRCU instead of sched-RCU. Inorder to
dereference the pointer to the probe functions, we could call
srcu_dereference, however this API will call back into lockdep to check
if the lock is held *before* the lockdep probe hooks have a chance to
run and annotate the IRQ enabled/disabled state.

For this reason we need a notrace variant of srcu_dereference since
otherwise we get lockdep splats. This patch adds the needed
srcu_dereference_notrace variant.

Reviewed-by: Paul E. McKenney <paulmck at linux.vnet.ibm.com>
Signed-off-by: Joel Fernandes (Google) <joel at joelfernandes.org>
---
 include/linux/srcu.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 2ec618979b20..a1c4947be877 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -135,6 +135,11 @@ static inline int srcu_read_lock_held(const struct srcu_struct *sp)
  */
 #define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0)
 
+/**
+ * srcu_dereference_notrace - no tracing and no lockdep calls from here
+ */
+#define srcu_dereference_notrace(p, sp) srcu_dereference_check((p), (sp), 1)
+
 /**
  * srcu_read_lock - register a new reader for an SRCU-protected structure.
  * @sp: srcu_struct in which to register the new reader.
-- 
2.17.1.1185.g55be947832-goog

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  parent reply	other threads:[~2018-06-07 20:39 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-07 20:38 [PATCH v9 0/7] Centralize and unify usage of preempt/irq Joel Fernandes
2018-06-07 20:38 ` Joel Fernandes
2018-06-07 20:38 ` joelaf
2018-06-07 20:38 ` [PATCH v9 1/7] srcu: Add notrace variants of srcu_read_{lock,unlock} Joel Fernandes
2018-06-07 20:38   ` Joel Fernandes
2018-06-07 20:38   ` joelaf
2018-06-07 20:38 ` Joel Fernandes [this message]
2018-06-07 20:38   ` [PATCH v9 2/7] srcu: Add notrace variant of srcu_dereference Joel Fernandes
2018-06-07 20:38   ` joelaf
2018-06-07 20:38 ` [PATCH v9 3/7] trace/irqsoff: Split reset into separate functions Joel Fernandes
2018-06-07 20:38   ` Joel Fernandes
2018-06-07 20:38   ` joelaf
2018-06-07 20:38 ` [PATCH v9 4/7] tracepoint: Make rcuidle tracepoint callers use SRCU Joel Fernandes
2018-06-07 20:38   ` Joel Fernandes
2018-06-07 20:38   ` joelaf
2018-06-07 20:38 ` [PATCH v9 5/7] tracing: Centralize preemptirq tracepoints and unify their usage Joel Fernandes
2018-06-07 20:38   ` Joel Fernandes
2018-06-07 20:38   ` joelaf
2018-06-07 20:38 ` [PATCH v9 6/7] lib: Add module to simulate atomic sections for testing preemptoff tracers Joel Fernandes
2018-06-07 20:38   ` Joel Fernandes
2018-06-07 20:38   ` joelaf
2018-06-07 20:38 ` [PATCH v9 7/7] kselftests: Add tests for the preemptoff and irqsoff tracers Joel Fernandes
2018-06-07 20:38   ` Joel Fernandes
2018-06-07 20:38   ` joelaf
2018-06-21 22:32 [PATCH v9 0/7] Centralize and unify usage of preempt/irq tracepoints Joel Fernandes
2018-06-21 22:32 ` [PATCH v9 2/7] srcu: Add notrace variant of srcu_dereference Joel Fernandes
2018-06-21 22:32   ` Joel Fernandes
2018-06-21 22:32   ` joel
2018-06-28 18:21 [PATCH v9 0/7] Centralize and unify usage of preempt/irq tracepoints Joel Fernandes
2018-06-28 18:21 ` [PATCH v9 2/7] srcu: Add notrace variant of srcu_dereference Joel Fernandes
2018-06-28 18:21   ` Joel Fernandes
2018-06-28 18:21   ` joel

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