From: paulmck@kernel.org
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
mingo@kernel.org, jiangshanlai@gmail.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
Frederic Weisbecker <frederic@kernel.org>,
Neeraj Upadhyay <neeraju@codeaurora.org>,
"Paul E . McKenney" <paulmck@kernel.org>
Subject: [PATCH tip/core/rcu 01/21] rcu/nocb: Turn enabled/offload states into a common flag
Date: Tue, 5 Jan 2021 20:48:33 -0800 [thread overview]
Message-ID: <20210106044853.20812-1-paulmck@kernel.org> (raw)
In-Reply-To: <20210106013950.GA14663@paulmck-ThinkPad-P72>
From: Frederic Weisbecker <frederic@kernel.org>
This commit gathers the rcu_segcblist ->enabled and ->offloaded property
field into a single ->flags bitmask to avoid further proliferation of
individual u8 fields in the structure. This change prepares for the
state formerly known as ->offloaded state to be modified at runtime.
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>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.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 6c01f09..4714b02 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];
@@ -73,8 +76,7 @@ struct rcu_segcblist {
long len;
#endif
long seglen[RCU_CBLIST_NSEGS];
- 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 094de25..406c67b 100644
--- a/kernel/rcu/rcu_segcblist.c
+++ b/kernel/rcu/rcu_segcblist.c
@@ -246,7 +246,7 @@ void rcu_segcblist_init(struct rcu_segcblist *rsclp)
rcu_segcblist_set_seglen(rsclp, i, 0);
}
rcu_segcblist_set_len(rsclp, 0);
- rsclp->enabled = 1;
+ rcu_segcblist_set_flags(rsclp, SEGCBLIST_ENABLED);
}
/*
@@ -257,7 +257,7 @@ 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);
}
/*
@@ -266,7 +266,7 @@ 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 18e101d..ff372db 100644
--- a/kernel/rcu/rcu_segcblist.h
+++ b/kernel/rcu/rcu_segcblist.h
@@ -53,19 +53,38 @@ 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);
}
/*
--
2.9.5
next prev parent reply other threads:[~2021-01-06 4:49 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-06 1:39 [PATCH tip/core/rcu 0/21] Provide runtime switching of offloaded CPUs Paul E. McKenney
2021-01-06 4:48 ` paulmck [this message]
2021-01-06 4:48 ` [PATCH tip/core/rcu 02/21] rcu/nocb: Provide basic callback offloading state machine bits paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 03/21] rcu/nocb: Always init segcblist on CPU up paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 04/21] rcu/nocb: De-offloading CB kthread paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 05/21] rcu/nocb: Don't deoffload an offline CPU with pending work paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 06/21] rcu/nocb: De-offloading GP kthread paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 07/21] rcu/nocb: Re-offload support paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 08/21] rcu/nocb: Shutdown nocb timer on de-offloading paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 09/21] rcu/nocb: Flush bypass before setting SEGCBLIST_SOFTIRQ_ONLY paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 10/21] rcu/nocb: Set SEGCBLIST_SOFTIRQ_ONLY at the very last stage of de-offloading paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 11/21] rcu/nocb: Only cond_resched() from actual offloaded batch processing paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 12/21] rcu/nocb: Process batch locally as long as offloading isn't complete paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 13/21] rcu/nocb: Locally accelerate callbacks " paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 14/21] cpu/hotplug: Add lockdep_is_cpus_held() paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 15/21] timer: Add timer_curr_running() paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 16/21] rcutorture: Test runtime toggling of CPUs' callback offloading paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 17/21] tools/rcutorture: Support nocb toggle in TREE01 paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 18/21] rcu/nocb: Add grace period and task state to show_rcu_nocb_state() output paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 19/21] rcu/nocb: Add nocb CB kthread list " paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 20/21] rcu/nocb: Code-style nits in callback-offloading toggling paulmck
2021-01-06 4:48 ` [PATCH tip/core/rcu 21/21] rcu: Do any deferred nocb wakeups at CPU offline time paulmck
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