[tip: core/rcu] srcu: Remove superfluous sdp->srcu_lock_count zero filling

From: tip-bot2 for Frederic Weisbecker
Date: Wed Jun 30 2021 - 09:51:22 EST


The following commit has been merged into the core/rcu branch of tip:

Commit-ID: 94df76a1971d9c61eb2c67ae10cc294b68cbd03b
Gitweb: https://git.kernel.org/tip/94df76a1971d9c61eb2c67ae10cc294b68cbd03b
Author: Frederic Weisbecker <frederic@xxxxxxxxxx>
AuthorDate: Fri, 02 Apr 2021 01:47:03 +02:00
Committer: Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Mon, 10 May 2021 16:03:34 -07:00

srcu: Remove superfluous sdp->srcu_lock_count zero filling

Because alloc_percpu() zeroes out the allocated memory, there is no need
to zero-fill newly allocated per-CPU memory. This commit therefore removes
the loop zeroing the ->srcu_lock_count and ->srcu_unlock_count arrays
from init_srcu_struct_nodes(). This is the only use of that function's
is_static parameter, which this commit also removes.

Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
Cc: Neeraj Upadhyay <neeraju@xxxxxxxxxxxxxx>
Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
Cc: Uladzislau Rezki <urezki@xxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
kernel/rcu/srcutree.c | 12 ++----------
1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index e26547b..3414aff 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -80,7 +80,7 @@ do { \
* srcu_read_unlock() running against them. So if the is_static parameter
* is set, don't initialize ->srcu_lock_count[] and ->srcu_unlock_count[].
*/
-static void init_srcu_struct_nodes(struct srcu_struct *ssp, bool is_static)
+static void init_srcu_struct_nodes(struct srcu_struct *ssp)
{
int cpu;
int i;
@@ -148,14 +148,6 @@ static void init_srcu_struct_nodes(struct srcu_struct *ssp, bool is_static)
timer_setup(&sdp->delay_work, srcu_delay_timer, 0);
sdp->ssp = ssp;
sdp->grpmask = 1 << (cpu - sdp->mynode->grplo);
- if (is_static)
- continue;
-
- /* Dynamically allocated, better be no srcu_read_locks()! */
- for (i = 0; i < ARRAY_SIZE(sdp->srcu_lock_count); i++) {
- sdp->srcu_lock_count[i] = 0;
- sdp->srcu_unlock_count[i] = 0;
- }
}
}

@@ -179,7 +171,7 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
ssp->sda = alloc_percpu(struct srcu_data);
if (!ssp->sda)
return -ENOMEM;
- init_srcu_struct_nodes(ssp, is_static);
+ init_srcu_struct_nodes(ssp);
ssp->srcu_gp_seq_needed_exp = 0;
ssp->srcu_last_gp_end = ktime_get_mono_fast_ns();
smp_store_release(&ssp->srcu_gp_seq_needed, 0); /* Init done. */