From: "tip-bot2 for Paul E. McKenney" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Kent Overstreet <kent.overstreet@gmail.com>,
Neeraj Upadhyay <neeraju@codeaurora.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: core/rcu] srcu: Provide internal interface to start a Tree SRCU grace period
Date: Mon, 15 Feb 2021 14:55:44 -0000 [thread overview]
Message-ID: <161340094498.20312.1445677559215645808.tip-bot2@tip-bot2> (raw)
The following commit has been merged into the core/rcu branch of tip:
Commit-ID: 29d2bb94a8a126ce80ffbb433b648b32fdea524e
Gitweb: https://git.kernel.org/tip/29d2bb94a8a126ce80ffbb433b648b32fdea524e
Author: Paul E. McKenney <paulmck@kernel.org>
AuthorDate: Fri, 13 Nov 2020 10:08:09 -08:00
Committer: Paul E. McKenney <paulmck@kernel.org>
CommitterDate: Mon, 04 Jan 2021 13:53:37 -08:00
srcu: Provide internal interface to start a Tree SRCU grace period
There is a need for a polling interface for SRCU grace periods.
This polling needs to initiate an SRCU grace period without having
to queue (and manage) a callback. This commit therefore splits the
Tree SRCU __call_srcu() function into callback-initialization and
queuing/start-grace-period portions, with the latter in a new function
named srcu_gp_start_if_needed(). This function may be passed a NULL
callback pointer, in which case it will refrain from queuing anything.
Why have the new function mess with queuing? Locking considerations,
of course!
Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Reviewed-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/srcutree.c | 66 +++++++++++++++++++++++-------------------
1 file changed, 37 insertions(+), 29 deletions(-)
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 0f23d20..9a7b650 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -808,6 +808,42 @@ static void srcu_leak_callback(struct rcu_head *rhp)
}
/*
+ * Start an SRCU grace period, and also queue the callback if non-NULL.
+ */
+static void srcu_gp_start_if_needed(struct srcu_struct *ssp, struct rcu_head *rhp, bool do_norm)
+{
+ unsigned long flags;
+ int idx;
+ bool needexp = false;
+ bool needgp = false;
+ unsigned long s;
+ struct srcu_data *sdp;
+
+ idx = srcu_read_lock(ssp);
+ sdp = raw_cpu_ptr(ssp->sda);
+ spin_lock_irqsave_rcu_node(sdp, flags);
+ rcu_segcblist_enqueue(&sdp->srcu_cblist, rhp);
+ rcu_segcblist_advance(&sdp->srcu_cblist,
+ rcu_seq_current(&ssp->srcu_gp_seq));
+ s = rcu_seq_snap(&ssp->srcu_gp_seq);
+ (void)rcu_segcblist_accelerate(&sdp->srcu_cblist, s);
+ if (ULONG_CMP_LT(sdp->srcu_gp_seq_needed, s)) {
+ sdp->srcu_gp_seq_needed = s;
+ needgp = true;
+ }
+ if (!do_norm && ULONG_CMP_LT(sdp->srcu_gp_seq_needed_exp, s)) {
+ sdp->srcu_gp_seq_needed_exp = s;
+ needexp = true;
+ }
+ spin_unlock_irqrestore_rcu_node(sdp, flags);
+ if (needgp)
+ srcu_funnel_gp_start(ssp, sdp, s, do_norm);
+ else if (needexp)
+ srcu_funnel_exp_start(ssp, sdp->mynode, s);
+ srcu_read_unlock(ssp, idx);
+}
+
+/*
* Enqueue an SRCU callback on the srcu_data structure associated with
* the current CPU and the specified srcu_struct structure, initiating
* grace-period processing if it is not already running.
@@ -838,13 +874,6 @@ static void srcu_leak_callback(struct rcu_head *rhp)
static void __call_srcu(struct srcu_struct *ssp, struct rcu_head *rhp,
rcu_callback_t func, bool do_norm)
{
- unsigned long flags;
- int idx;
- bool needexp = false;
- bool needgp = false;
- unsigned long s;
- struct srcu_data *sdp;
-
check_init_srcu_struct(ssp);
if (debug_rcu_head_queue(rhp)) {
/* Probable double call_srcu(), so leak the callback. */
@@ -853,28 +882,7 @@ static void __call_srcu(struct srcu_struct *ssp, struct rcu_head *rhp,
return;
}
rhp->func = func;
- idx = srcu_read_lock(ssp);
- sdp = raw_cpu_ptr(ssp->sda);
- spin_lock_irqsave_rcu_node(sdp, flags);
- rcu_segcblist_enqueue(&sdp->srcu_cblist, rhp);
- rcu_segcblist_advance(&sdp->srcu_cblist,
- rcu_seq_current(&ssp->srcu_gp_seq));
- s = rcu_seq_snap(&ssp->srcu_gp_seq);
- (void)rcu_segcblist_accelerate(&sdp->srcu_cblist, s);
- if (ULONG_CMP_LT(sdp->srcu_gp_seq_needed, s)) {
- sdp->srcu_gp_seq_needed = s;
- needgp = true;
- }
- if (!do_norm && ULONG_CMP_LT(sdp->srcu_gp_seq_needed_exp, s)) {
- sdp->srcu_gp_seq_needed_exp = s;
- needexp = true;
- }
- spin_unlock_irqrestore_rcu_node(sdp, flags);
- if (needgp)
- srcu_funnel_gp_start(ssp, sdp, s, do_norm);
- else if (needexp)
- srcu_funnel_exp_start(ssp, sdp->mynode, s);
- srcu_read_unlock(ssp, idx);
+ srcu_gp_start_if_needed(ssp, rhp, do_norm);
}
/**
reply other threads:[~2021-02-15 14:59 UTC|newest]
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