linux-kernel - [PATCH v2 3/9] rcu/sync: Remove custom check for reader-section

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Message-Id: <20190712170024.111093-4-joel@joelfernandes.org>
Date:   Fri, 12 Jul 2019 13:00:18 -0400
From:   "Joel Fernandes (Google)" <joel@...lfernandes.org>
To:     linux-kernel@...r.kernel.org
Cc:     "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        Oleg Nesterov <oleg@...hat.com>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Borislav Petkov <bp@...en8.de>, c0d1n61at3@...il.com,
        "David S. Miller" <davem@...emloft.net>, edumazet@...gle.com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Josh Triplett <josh@...htriplett.org>, keescook@...omium.org,
        kernel-hardening@...ts.openwall.com, kernel-team@...roid.com,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Len Brown <lenb@...nel.org>, linux-acpi@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-pm@...r.kernel.org,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        neilb@...e.com, netdev@...r.kernel.org,
        "Paul E. McKenney" <paulmck@...ux.ibm.com>,
        Pavel Machek <pavel@....cz>, peterz@...radead.org,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Rasmus Villemoes <rasmus.villemoes@...vas.dk>,
        rcu@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        Tejun Heo <tj@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>, will@...nel.org,
        x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT))
Subject: [PATCH v2 3/9] rcu/sync: Remove custom check for reader-section

The rcu/sync code was doing its own check whether we are in a reader
section. With RCU consolidating flavors and the generic helper added in
this series, this is no longer need. We can just use the generic helper
and it results in a nice cleanup.

Cc: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
---
Please note: Only build and boot tested this particular patch so far.

 include/linux/rcu_sync.h |  5 ++---
 kernel/rcu/sync.c        | 22 ----------------------
 2 files changed, 2 insertions(+), 25 deletions(-)

diff --git a/include/linux/rcu_sync.h b/include/linux/rcu_sync.h
index 6fc53a1345b3..c954f1efc919 100644
--- a/include/linux/rcu_sync.h
+++ b/include/linux/rcu_sync.h
@@ -39,9 +39,8 @@ extern void rcu_sync_lockdep_assert(struct rcu_sync *);
  */
 static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
 {
-#ifdef CONFIG_PROVE_RCU
-	rcu_sync_lockdep_assert(rsp);
-#endif
+	RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(),
+			 "suspicious rcu_sync_is_idle() usage");
 	return !rsp->gp_state; /* GP_IDLE */
 }
 
diff --git a/kernel/rcu/sync.c b/kernel/rcu/sync.c
index a8304d90573f..535e02601f56 100644
--- a/kernel/rcu/sync.c
+++ b/kernel/rcu/sync.c
@@ -10,37 +10,25 @@
 #include <linux/rcu_sync.h>
 #include <linux/sched.h>
 
-#ifdef CONFIG_PROVE_RCU
-#define __INIT_HELD(func)	.held = func,
-#else
-#define __INIT_HELD(func)
-#endif
-
 static const struct {
 	void (*sync)(void);
 	void (*call)(struct rcu_head *, void (*)(struct rcu_head *));
 	void (*wait)(void);
-#ifdef CONFIG_PROVE_RCU
-	int  (*held)(void);
-#endif
 } gp_ops[] = {
 	[RCU_SYNC] = {
 		.sync = synchronize_rcu,
 		.call = call_rcu,
 		.wait = rcu_barrier,
-		__INIT_HELD(rcu_read_lock_held)
 	},
 	[RCU_SCHED_SYNC] = {
 		.sync = synchronize_rcu,
 		.call = call_rcu,
 		.wait = rcu_barrier,
-		__INIT_HELD(rcu_read_lock_sched_held)
 	},
 	[RCU_BH_SYNC] = {
 		.sync = synchronize_rcu,
 		.call = call_rcu,
 		.wait = rcu_barrier,
-		__INIT_HELD(rcu_read_lock_bh_held)
 	},
 };
 
@@ -49,16 +37,6 @@ enum { CB_IDLE = 0, CB_PENDING, CB_REPLAY };
 
 #define	rss_lock	gp_wait.lock
 
-#ifdef CONFIG_PROVE_RCU
-void rcu_sync_lockdep_assert(struct rcu_sync *rsp)
-{
-	RCU_LOCKDEP_WARN(!gp_ops[rsp->gp_type].held(),
-			 "suspicious rcu_sync_is_idle() usage");
-}
-
-EXPORT_SYMBOL_GPL(rcu_sync_lockdep_assert);
-#endif
-
 /**
  * rcu_sync_init() - Initialize an rcu_sync structure
  * @rsp: Pointer to rcu_sync structure to be initialized
-- 
2.22.0.510.g264f2c817a-goog