From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com,
rostedt@goodmis.org, Puranjay Mohan <puranjay@kernel.org>,
"Paul E . McKenney" <paulmck@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>
Subject: [PATCH RFC 03/12] rcu/segcblist: Add SRCU and Tasks RCU wrapper functions
Date: Thu, 30 Jul 2026 17:57:23 -0700 [thread overview]
Message-ID: <20260731005732.3530999-3-paulmck@kernel.org> (raw)
In-Reply-To: <58bcd561-0520-43ff-95b0-1ed10e1e3bff@paulmck-laptop>
From: Puranjay Mohan <puranjay@kernel.org>
Add srcu_segcblist_advance() and srcu_segcblist_accelerate() wrappers
that forward to the core rcu_segcblist_advance() and
rcu_segcblist_accelerate() functions, and switch all SRCU (srcutree.c)
and Tasks RCU (tasks.h) callers to use these wrappers.
This isolates SRCU and Tasks RCU from upcoming changes to the core
advance/accelerate functions, which will switch to struct
rcu_gp_seq for dual normal/expedited GP tracking. Because SRCU and
Tasks RCU use only normal GP sequences, their wrappers will maintain the
existing unsigned long interface.
No functional change.
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/rcu_segcblist.c | 10 ++++++++++
kernel/rcu/rcu_segcblist.h | 2 ++
kernel/rcu/srcutree.c | 14 +++++++-------
kernel/rcu/tasks.h | 8 ++++----
4 files changed, 23 insertions(+), 11 deletions(-)
diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c
index 298a2c573f02c3..da39d818b01b10 100644
--- a/kernel/rcu/rcu_segcblist.c
+++ b/kernel/rcu/rcu_segcblist.c
@@ -620,3 +620,13 @@ void rcu_segcblist_merge(struct rcu_segcblist *dst_rsclp,
rcu_segcblist_init(src_rsclp);
}
+
+void srcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq)
+{
+ rcu_segcblist_advance(rsclp, seq);
+}
+
+bool srcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq)
+{
+ return rcu_segcblist_accelerate(rsclp, seq);
+}
diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h
index fadc08ad4b7b60..956f2967d9d294 100644
--- a/kernel/rcu/rcu_segcblist.h
+++ b/kernel/rcu/rcu_segcblist.h
@@ -143,3 +143,5 @@ void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq);
bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq);
void rcu_segcblist_merge(struct rcu_segcblist *dst_rsclp,
struct rcu_segcblist *src_rsclp);
+void srcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq);
+bool srcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq);
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 7c2f7cc131f7ae..519a35719c8961 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -1351,7 +1351,7 @@ static unsigned long srcu_gp_start_if_needed(struct srcu_struct *ssp,
* 2) The grace period for RCU_WAIT_TAIL is seen as started but not
* completed so rcu_seq_current() returns X + SRCU_STATE_SCAN1.
*
- * 3) This value is passed to rcu_segcblist_advance() which can't move
+ * 3) This value is passed to srcu_segcblist_advance() which can't move
* any segment forward and fails.
*
* 4) srcu_gp_start_if_needed() still proceeds with callback acceleration.
@@ -1360,15 +1360,15 @@ static unsigned long srcu_gp_start_if_needed(struct srcu_struct *ssp,
* RCU_NEXT_READY_TAIL segment as started (ie: X + 4 + SRCU_STATE_SCAN1)
* so it returns a snapshot of the next grace period, which is X + 12.
*
- * 5) The value of X + 12 is passed to rcu_segcblist_accelerate() but the
+ * 5) The value of X + 12 is passed to srcu_segcblist_accelerate() but the
* freshly enqueued callback in RCU_NEXT_TAIL can't move to
* RCU_NEXT_READY_TAIL which already has callbacks for a previous grace
* period (gp_num = X + 8). So acceleration fails.
*/
s = rcu_seq_snap(&ssp->srcu_sup->srcu_gp_seq);
if (rhp) {
- rcu_segcblist_advance(&sdp->srcu_cblist,
- rcu_seq_current(&ssp->srcu_sup->srcu_gp_seq));
+ srcu_segcblist_advance(&sdp->srcu_cblist,
+ rcu_seq_current(&ssp->srcu_sup->srcu_gp_seq));
/*
* Acceleration can never fail because the base current gp_seq
* used for acceleration is <= the value of gp_seq used for
@@ -1376,7 +1376,7 @@ static unsigned long srcu_gp_start_if_needed(struct srcu_struct *ssp,
* always be able to be emptied by the acceleration into the
* RCU_NEXT_READY_TAIL or RCU_WAIT_TAIL segments.
*/
- WARN_ON_ONCE(!rcu_segcblist_accelerate(&sdp->srcu_cblist, s));
+ WARN_ON_ONCE(!srcu_segcblist_accelerate(&sdp->srcu_cblist, s));
}
if (ULONG_CMP_LT(sdp->srcu_gp_seq_needed, s)) {
sdp->srcu_gp_seq_needed = s;
@@ -1891,8 +1891,8 @@ static void srcu_invoke_callbacks(struct work_struct *work)
rcu_cblist_init(&ready_cbs);
raw_spin_lock_irq_rcu_node(sdp);
WARN_ON_ONCE(!rcu_segcblist_segempty(&sdp->srcu_cblist, RCU_NEXT_TAIL));
- rcu_segcblist_advance(&sdp->srcu_cblist,
- rcu_seq_current(&ssp->srcu_sup->srcu_gp_seq));
+ srcu_segcblist_advance(&sdp->srcu_cblist,
+ rcu_seq_current(&ssp->srcu_sup->srcu_gp_seq));
/*
* Although this function is theoretically re-entrant, concurrent
* callbacks invocation is disallowed to avoid executing an SRCU barrier
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index f4da5fad70f516..92971499a12c55 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -481,8 +481,8 @@ static int rcu_tasks_need_gpcb(struct rcu_tasks *rtp)
if (cpu > 0)
ncbsnz += n;
}
- rcu_segcblist_advance(&rtpcp->cblist, rcu_seq_current(&rtp->tasks_gp_seq));
- (void)rcu_segcblist_accelerate(&rtpcp->cblist, rcu_seq_snap(&rtp->tasks_gp_seq));
+ srcu_segcblist_advance(&rtpcp->cblist, rcu_seq_current(&rtp->tasks_gp_seq));
+ (void)srcu_segcblist_accelerate(&rtpcp->cblist, rcu_seq_snap(&rtp->tasks_gp_seq));
if (rtpcp->urgent_gp > 0 && rcu_segcblist_pend_cbs(&rtpcp->cblist)) {
if (rtp->lazy_jiffies)
rtpcp->urgent_gp--;
@@ -565,7 +565,7 @@ static void rcu_tasks_invoke_cbs(struct rcu_tasks *rtp, struct rcu_tasks_percpu
if (rcu_segcblist_empty(&rtpcp->cblist))
return;
raw_spin_lock_irqsave_rcu_node(rtpcp, flags);
- rcu_segcblist_advance(&rtpcp->cblist, rcu_seq_current(&rtp->tasks_gp_seq));
+ srcu_segcblist_advance(&rtpcp->cblist, rcu_seq_current(&rtp->tasks_gp_seq));
rcu_segcblist_extract_done_cbs(&rtpcp->cblist, &rcl);
raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags);
len = rcl.len;
@@ -578,7 +578,7 @@ static void rcu_tasks_invoke_cbs(struct rcu_tasks *rtp, struct rcu_tasks_percpu
}
raw_spin_lock_irqsave_rcu_node(rtpcp, flags);
rcu_segcblist_add_len(&rtpcp->cblist, -len);
- (void)rcu_segcblist_accelerate(&rtpcp->cblist, rcu_seq_snap(&rtp->tasks_gp_seq));
+ (void)srcu_segcblist_accelerate(&rtpcp->cblist, rcu_seq_snap(&rtp->tasks_gp_seq));
raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags);
}
--
2.40.1
next prev parent reply other threads:[~2026-07-31 0:57 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-31 0:57 [PATCH 0/12] Expediting normal RCU callbacks Paul E. McKenney
2026-07-31 0:57 ` [PATCH RFC 01/12] rcu: Remove unused rdp parameter from trace_rcu_this_gp() Paul E. McKenney
2026-07-31 0:57 ` [PATCH RFC 02/12] rcu: Rename struct rcu_gp_oldstate to rcu_gp_seq Paul E. McKenney
2026-07-31 0:57 ` Paul E. McKenney [this message]
2026-07-31 0:57 ` [PATCH RFC 04/12] rcu/segcblist: Factor out rcu_segcblist_advance_compact() helper Paul E. McKenney
2026-07-31 0:57 ` [PATCH RFC 05/12] rcu/segcblist: Track segment grace periods with struct rcu_gp_seq Paul E. McKenney
2026-07-31 0:57 ` [PATCH RFC 06/12] rcu: Add RCU_GET_STATE_NOT_TRACKED for subsystems without expedited GPs Paul E. McKenney
2026-07-31 0:57 ` [PATCH RFC 07/12] rcu: Enable RCU callbacks to benefit from expedited grace periods Paul E. McKenney
2026-07-31 0:57 ` [PATCH RFC 08/12] rcu: Update comments for gp_seq and expedited GP tracking Paul E. McKenney
2026-07-31 0:57 ` [PATCH RFC 09/12] rcu: Wake NOCB rcuog kthreads on expedited grace period completion Paul E. McKenney
2026-07-31 0:57 ` [PATCH RFC 10/12] rcu: Detect expedited grace period completion in rcu_pending() Paul E. McKenney
2026-07-31 0:57 ` [PATCH RFC 11/12] rcu: Advance callbacks for expedited GP completion in rcu_core() Paul E. McKenney
2026-07-31 0:57 ` [PATCH RFC 12/12] rcuscale: Add concurrent expedited GP threads for callback scaling tests Paul E. McKenney
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260731005732.3530999-3-paulmck@kernel.org \
--to=paulmck@kernel.org \
--cc=frederic@kernel.org \
--cc=kernel-team@meta.com \
--cc=linux-kernel@vger.kernel.org \
--cc=puranjay@kernel.org \
--cc=rcu@vger.kernel.org \
--cc=rostedt@goodmis.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.