From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: [md PATCH 14/15] percpu-refcount: support synchronous switch to atomic mode. Date: Wed, 15 Mar 2017 14:05:14 +1100 Message-ID: <148954711451.18641.16530335727683897485.stgit@noble> References: <148954692173.18641.1294690639716682540.stgit@noble> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <148954692173.18641.1294690639716682540.stgit@noble> Sender: linux-raid-owner@vger.kernel.org To: Shaohua Li Cc: linux-raid@vger.kernel.org, hch@lst.de List-Id: linux-raid.ids percpu_ref_switch_to_atomic_sync() schedules the switch to atomic mode, then waits for it to complete. Also export percpu_ref_switch_to_* so they can be used from modules. Signed-off-by: NeilBrown --- include/linux/percpu-refcount.h | 1 + lib/percpu-refcount.c | 18 ++++++++++++++++++ 2 files changed, 19 insertions(+) diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h index 3a481a49546e..c13dceb87b60 100644 --- a/include/linux/percpu-refcount.h +++ b/include/linux/percpu-refcount.h @@ -99,6 +99,7 @@ int __must_check percpu_ref_init(struct percpu_ref *ref, void percpu_ref_exit(struct percpu_ref *ref); void percpu_ref_switch_to_atomic(struct percpu_ref *ref, percpu_ref_func_t *confirm_switch); +void percpu_ref_switch_to_atomic_sync(struct percpu_ref *ref); void percpu_ref_switch_to_percpu(struct percpu_ref *ref); void percpu_ref_kill_and_confirm(struct percpu_ref *ref, percpu_ref_func_t *confirm_kill); diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c index 9ac959ef4cae..d133ed43a375 100644 --- a/lib/percpu-refcount.c +++ b/lib/percpu-refcount.c @@ -260,6 +260,23 @@ void percpu_ref_switch_to_atomic(struct percpu_ref *ref, spin_unlock_irqrestore(&percpu_ref_switch_lock, flags); } +EXPORT_SYMBOL_GPL(percpu_ref_switch_to_atomic); + +/** + * percpu_ref_switch_to_atomic_sync - switch a percpu_ref to atomic mode + * @ref: percpu_ref to switch to atomic mode + * + * Schedule switching the ref to atomic mode, and wait for the + * switch to complete. Caller must ensure that no other thread + * will switch back to percpu mode. + * + */ +void percpu_ref_switch_to_atomic_sync(struct percpu_ref *ref) +{ + percpu_ref_switch_to_atomic(ref, NULL); + wait_event(percpu_ref_switch_waitq, !ref->confirm_switch); +} +EXPORT_SYMBOL_GPL(percpu_ref_switch_to_atomic_sync); /** * percpu_ref_switch_to_percpu - switch a percpu_ref to percpu mode @@ -290,6 +307,7 @@ void percpu_ref_switch_to_percpu(struct percpu_ref *ref) spin_unlock_irqrestore(&percpu_ref_switch_lock, flags); } +EXPORT_SYMBOL_GPL(percpu_ref_switch_to_percpu); /** * percpu_ref_kill_and_confirm - drop the initial ref and schedule confirmation