[PATCH v3 06/14] ipc: Remove redundant rcu_read_lock/unlock() in spin_lock
From: pengdonglin <hidden>
Date: 2025-09-16 04:48:54
Also in:
cgroups, intel-gfx, linux-acpi, linux-fsdevel, linux-nfs, linux-rt-devel, linux-s390, linux-security-module, linux-wireless, lkml
Subsystem:
the rest · Maintainer:
Linus Torvalds
From: pengdonglin <redacted>
Since commit a8bb74acd8efe ("rcu: Consolidate RCU-sched update-side function definitions")
there is no difference between rcu_read_lock(), rcu_read_lock_bh() and
rcu_read_lock_sched() in terms of RCU read section and the relevant grace
period. That means that spin_lock(), which implies rcu_read_lock_sched(),
also implies rcu_read_lock().
There is no need no explicitly start a RCU read section if one has already
been started implicitly by spin_lock().
Simplify the code and remove the inner rcu_read_lock() invocation.
Signed-off-by: pengdonglin <redacted>
Signed-off-by: pengdonglin <redacted>
---
ipc/msg.c | 1 -
ipc/sem.c | 1 -
ipc/shm.c | 1 -
ipc/util.c | 2 --
4 files changed, 5 deletions(-)
diff --git a/ipc/msg.c b/ipc/msg.c
index ee6af4fe52bf..1e579b57023f 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c@@ -179,7 +179,6 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params) } ipc_unlock_object(&msq->q_perm); - rcu_read_unlock(); return msq->q_perm.id; }
diff --git a/ipc/sem.c b/ipc/sem.c
index a39cdc7bf88f..38ad57b2b558 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c@@ -579,7 +579,6 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params) ns->used_sems += nsems; sem_unlock(sma, -1); - rcu_read_unlock(); return sma->sem_perm.id; }
diff --git a/ipc/shm.c b/ipc/shm.c
index a9310b6dbbc3..61fae1b6a18e 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c@@ -795,7 +795,6 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params) error = shp->shm_perm.id; ipc_unlock_object(&shp->shm_perm); - rcu_read_unlock(); return error; no_id:
diff --git a/ipc/util.c b/ipc/util.c
index cae60f11d9c2..1be691b5dcad 100644
--- a/ipc/util.c
+++ b/ipc/util.c@@ -293,7 +293,6 @@ int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit) idr_preload(GFP_KERNEL); spin_lock_init(&new->lock); - rcu_read_lock(); spin_lock(&new->lock); current_euid_egid(&euid, &egid);
@@ -316,7 +315,6 @@ int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit) if (idx < 0) { new->deleted = true; spin_unlock(&new->lock); - rcu_read_unlock(); return idx; }
--
2.34.1