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From: joelaf@google.com (Joel Fernandes)
Subject: [PATCH v8 3/8] srcu: Add notrace variant of srcu_dereference
Date: Tue, 29 May 2018 17:04:55 -0700	[thread overview]
Message-ID: <20180530000500.257225-4-joel@joelfernandes.org> (raw)
Message-ID: <20180530000455.zmr1D68v5qSxGd6_W3A98xMT8GF0NOIpTVvUgyorWpI@z> (raw)
In-Reply-To: <20180530000500.257225-1-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.
-- 
2.17.0.921.gf22659ad46-goog

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  parent reply	other threads:[~2018-05-30  0:04 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-30  0:04 [PATCH v8 0/8] Centralize and unify usage of preempt/irq tracepoints Joel Fernandes
2018-05-30  0:04 ` Joel Fernandes
2018-05-30  0:04 ` joelaf
2018-05-30  0:04 ` [PATCH v8 1/8] softirq: reorder trace_softirqs_on to prevent lockdep splat Joel Fernandes
2018-05-30  0:04   ` Joel Fernandes
2018-05-30  0:04   ` joelaf
2018-05-30  0:04 ` [PATCH v8 2/8] srcu: Add notrace variants of srcu_read_{lock,unlock} Joel Fernandes
2018-05-30  0:04   ` Joel Fernandes
2018-05-30  0:04   ` joelaf
2018-05-30  0:04 ` Joel Fernandes [this message]
2018-05-30  0:04   ` [PATCH v8 3/8] srcu: Add notrace variant of srcu_dereference Joel Fernandes
2018-05-30  0:04   ` joelaf
2018-05-30  0:04 ` [PATCH v8 4/8] trace/irqsoff: Split reset into separate functions Joel Fernandes
2018-05-30  0:04   ` Joel Fernandes
2018-05-30  0:04   ` joelaf
2018-05-30  0:04 ` [PATCH v8 5/8] tracepoint: Make rcuidle tracepoint callers use SRCU Joel Fernandes
2018-05-30  0:04   ` Joel Fernandes
2018-05-30  0:04   ` joelaf
2018-05-31  6:50   ` Mathieu Desnoyers
2018-05-31  6:50     ` Mathieu Desnoyers
2018-05-31  6:50     ` mathieu.desnoyers
2018-05-31 17:51     ` Joel Fernandes
2018-05-31 17:51       ` Joel Fernandes
2018-05-31 17:51       ` joel
2018-06-02  1:17       ` Mathieu Desnoyers
2018-06-02  1:17         ` Mathieu Desnoyers
2018-06-02  1:17         ` mathieu.desnoyers
2018-05-30  0:04 ` [PATCH v8 6/8] tracing: Centralize preemptirq tracepoints and unify their usage Joel Fernandes
2018-05-30  0:04   ` Joel Fernandes
2018-05-30  0:04   ` joelaf
2018-05-31  1:56   ` Namhyung Kim
2018-05-31  1:56     ` Namhyung Kim
2018-05-31  1:56     ` namhyung
2018-05-31  6:26     ` Joel Fernandes
2018-05-31  6:26       ` Joel Fernandes
2018-05-31  6:26       ` joel
2018-05-30  0:04 ` [PATCH v8 7/8] lib: Add module to simulate atomic sections for testing preemptoff tracers Joel Fernandes
2018-05-30  0:04   ` Joel Fernandes
2018-05-30  0:04   ` joelaf
2018-06-05 23:01   ` Joel Fernandes
2018-06-05 23:01     ` Joel Fernandes
2018-06-05 23:01     ` joel
2018-06-05 23:53   ` Joel Fernandes
2018-06-05 23:53     ` Joel Fernandes
2018-06-05 23:53     ` joel
2018-06-06  7:48     ` Andy Shevchenko
2018-06-06  7:48       ` Andy Shevchenko
2018-06-06  7:48       ` andriy.shevchenko
2018-05-30  0:05 ` [PATCH v8 8/8] kselftests: Add tests for the preemptoff and irqsoff tracers Joel Fernandes
2018-05-30  0:05   ` Joel Fernandes
2018-05-30  0:05   ` joelaf
2018-05-31  6:45   ` kbuild test robot
2018-05-31  6:45     ` kbuild test robot
2018-05-31  6:45     ` lkp
2018-05-31  6:45   ` [PATCH] kselftests: fix ptr_ret.cocci warnings kbuild test robot
2018-05-31  6:45     ` kbuild test robot
2018-05-31  6:45     ` fengguang.wu
2018-05-31  7:14     ` Joel Fernandes
2018-05-31  7:14       ` Joel Fernandes
2018-05-31  7:14       ` joel

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