From: Frederic Weisbecker <frederic@kernel.org>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
"Paul E . McKenney" <paulmck@kernel.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Neeraj Upadhyay <neeraju@codeaurora.org>,
Joel Fernandes <joel@joelfernandes.org>,
Josh Triplett <josh@joshtriplett.org>
Subject: [PATCH 02/16] rcu: Turn enabled/offload states into a common flag
Date: Fri, 23 Oct 2020 16:46:35 +0200 [thread overview]
Message-ID: <20201023144649.53046-3-frederic@kernel.org> (raw)
In-Reply-To: <20201023144649.53046-1-frederic@kernel.org>
Gather the segcblist properties in a common map to avoid spreading
booleans in the structure. And this prepares for the offloaded state to
be mutable on runtime.
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
---
include/linux/rcu_segcblist.h | 6 ++++--
kernel/rcu/rcu_segcblist.c | 6 +++---
kernel/rcu/rcu_segcblist.h | 23 +++++++++++++++++++++--
3 files changed, 28 insertions(+), 7 deletions(-)
diff --git a/include/linux/rcu_segcblist.h b/include/linux/rcu_segcblist.h
index b36afe7b22c9..dca2f39ee67f 100644
--- a/include/linux/rcu_segcblist.h
+++ b/include/linux/rcu_segcblist.h
@@ -63,6 +63,9 @@ struct rcu_cblist {
#define RCU_NEXT_TAIL 3
#define RCU_CBLIST_NSEGS 4
+#define SEGCBLIST_ENABLED BIT(0)
+#define SEGCBLIST_OFFLOADED BIT(1)
+
struct rcu_segcblist {
struct rcu_head *head;
struct rcu_head **tails[RCU_CBLIST_NSEGS];
@@ -72,8 +75,7 @@ struct rcu_segcblist {
#else
long len;
#endif
- u8 enabled;
- u8 offloaded;
+ u8 flags;
};
#define RCU_SEGCBLIST_INITIALIZER(n) \
diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c
index 2d2a6b6b9dfb..e6522fa54311 100644
--- a/kernel/rcu/rcu_segcblist.c
+++ b/kernel/rcu/rcu_segcblist.c
@@ -152,7 +152,7 @@ void rcu_segcblist_init(struct rcu_segcblist *rsclp)
for (i = 0; i < RCU_CBLIST_NSEGS; i++)
rsclp->tails[i] = &rsclp->head;
rcu_segcblist_set_len(rsclp, 0);
- rsclp->enabled = 1;
+ rcu_segcblist_set_flags(rsclp, SEGCBLIST_ENABLED);
}
/*
@@ -163,7 +163,7 @@ void rcu_segcblist_disable(struct rcu_segcblist *rsclp)
{
WARN_ON_ONCE(!rcu_segcblist_empty(rsclp));
WARN_ON_ONCE(rcu_segcblist_n_cbs(rsclp));
- rsclp->enabled = 0;
+ rcu_segcblist_clear_flags(rsclp, SEGCBLIST_ENABLED);
}
/*
@@ -172,7 +172,7 @@ void rcu_segcblist_disable(struct rcu_segcblist *rsclp)
*/
void rcu_segcblist_offload(struct rcu_segcblist *rsclp)
{
- rsclp->offloaded = 1;
+ rcu_segcblist_set_flags(rsclp, SEGCBLIST_OFFLOADED);
}
/*
diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h
index 492262bcb591..fc98761e3ee9 100644
--- a/kernel/rcu/rcu_segcblist.h
+++ b/kernel/rcu/rcu_segcblist.h
@@ -50,19 +50,38 @@ static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp)
#endif
}
+static inline void rcu_segcblist_set_flags(struct rcu_segcblist *rsclp,
+ int flags)
+{
+ rsclp->flags |= flags;
+}
+
+static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
+ int flags)
+{
+ rsclp->flags &= ~flags;
+}
+
+static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
+ int flags)
+{
+ return READ_ONCE(rsclp->flags) & flags;
+}
+
/*
* Is the specified rcu_segcblist enabled, for example, not corresponding
* to an offline CPU?
*/
static inline bool rcu_segcblist_is_enabled(struct rcu_segcblist *rsclp)
{
- return rsclp->enabled;
+ return rcu_segcblist_test_flags(rsclp, SEGCBLIST_ENABLED);
}
/* Is the specified rcu_segcblist offloaded? */
static inline bool rcu_segcblist_is_offloaded(struct rcu_segcblist *rsclp)
{
- return IS_ENABLED(CONFIG_RCU_NOCB_CPU) && rsclp->offloaded;
+ return IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
+ rcu_segcblist_test_flags(rsclp, SEGCBLIST_OFFLOADED);
}
/*
--
2.25.1
next prev parent reply other threads:[~2020-10-23 14:47 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-23 14:46 [PATCH 00/16] rcu/nocb: De-offload and re-offload support v3 Frederic Weisbecker
2020-10-23 14:46 ` [PATCH 01/16] rcu: Implement rcu_segcblist_is_offloaded() config dependent Frederic Weisbecker
2020-10-23 14:46 ` Frederic Weisbecker [this message]
2020-10-23 14:46 ` [PATCH 03/16] rcu: Provide basic callback offloading state machine bits Frederic Weisbecker
2020-10-23 14:46 ` [PATCH 04/16] rcu/nocb: Always init segcblist on CPU up Frederic Weisbecker
2020-10-23 14:46 ` [PATCH 05/16] rcu: De-offloading CB kthread Frederic Weisbecker
2020-11-02 13:38 ` Boqun Feng
2020-11-04 14:31 ` Frederic Weisbecker
2020-11-04 14:42 ` Boqun Feng
2020-11-04 14:45 ` Frederic Weisbecker
2020-10-23 14:46 ` [PATCH 06/16] rcu/nocb: Don't deoffload an offline CPU with pending work Frederic Weisbecker
2020-10-23 14:46 ` [PATCH 07/16] rcu: De-offloading GP kthread Frederic Weisbecker
2020-10-23 14:46 ` [PATCH 08/16] rcu: Re-offload support Frederic Weisbecker
2020-10-23 14:46 ` [PATCH 09/16] rcu: Shutdown nocb timer on de-offloading Frederic Weisbecker
2020-10-23 14:46 ` [PATCH 10/16] rcu: Flush bypass before setting SEGCBLIST_SOFTIRQ_ONLY Frederic Weisbecker
2020-10-23 14:46 ` [PATCH 11/16] rcu: Set SEGCBLIST_SOFTIRQ_ONLY at the very last stage of de-offloading Frederic Weisbecker
2020-10-23 14:46 ` [PATCH 12/16] rcu/nocb: Only cond_resched() from actual offloaded batch processing Frederic Weisbecker
2020-10-23 14:46 ` [PATCH 13/16] rcu: Process batch locally as long as offloading isn't complete Frederic Weisbecker
2020-10-23 14:46 ` [PATCH 14/16] rcu: Locally accelerate callbacks " Frederic Weisbecker
2020-10-23 14:46 ` [PATCH 15/16] rcutorture: Test runtime toggling of CPUs' callback offloading Frederic Weisbecker
2020-10-23 14:46 ` [PATCH 16/16] tools/rcutorture: Support nocb toggle in TREE01 Frederic Weisbecker
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