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From: Harald Freudenberger <freude@linux.ibm.com>
To: pengdonglin <dolinux.peng@gmail.com>
Cc: tj@kernel.org, tony.luck@intel.com, jani.nikula@linux.intel.com,
	ap420073@gmail.com, jv@jvosburgh.net, bcrl@kvack.org,
	trondmy@kernel.org, longman@redhat.com, kees@kernel.org,
	bigeasy@linutronix.de, hdanton@sina.com, paulmck@kernel.org,
	linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev,
	linux-nfs@vger.kernel.org, linux-aio@kvack.org,
	linux-fsdevel@vger.kernel.org,
	linux-security-module@vger.kernel.org, netdev@vger.kernel.org,
	intel-gfx@lists.freedesktop.org, linux-wireless@vger.kernel.org,
	linux-acpi@vger.kernel.org, linux-s390@vger.kernel.org,
	cgroups@vger.kernel.org, Holger Dengler <dengler@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	pengdonglin <pengdonglin@xiaomi.com>
Subject: Re: [PATCH v3 05/14] s390/pkey: Remove redundant rcu_read_lock/unlock() in spin_lock
Date: Tue, 16 Sep 2025 12:51:03 +0200	[thread overview]
Message-ID: <31be6bb6541bb3e338e3025ac9e8fce5@linux.ibm.com> (raw)
In-Reply-To: <20250916044735.2316171-6-dolinux.peng@gmail.com>

On 2025-09-16 06:47, pengdonglin wrote:
> From: pengdonglin <pengdonglin@xiaomi.com>
> 
> 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.
> 
> Cc: Harald Freudenberger <freude@linux.ibm.com>
> Cc: Holger Dengler <dengler@linux.ibm.com>
> Cc: Vasily Gorbik <gor@linux.ibm.com>
> Cc: Alexander Gordeev <agordeev@linux.ibm.com>
> Signed-off-by: pengdonglin <pengdonglin@xiaomi.com>
> Signed-off-by: pengdonglin <dolinux.peng@gmail.com>
> ---
>  drivers/s390/crypto/pkey_base.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/drivers/s390/crypto/pkey_base.c 
> b/drivers/s390/crypto/pkey_base.c
> index b15741461a63..4c4a9feecccc 100644
> --- a/drivers/s390/crypto/pkey_base.c
> +++ b/drivers/s390/crypto/pkey_base.c
> @@ -48,16 +48,13 @@ int pkey_handler_register(struct pkey_handler 
> *handler)
> 
>  	spin_lock(&handler_list_write_lock);
> 
> -	rcu_read_lock();
>  	list_for_each_entry_rcu(h, &handler_list, list) {
>  		if (h == handler) {
> -			rcu_read_unlock();
>  			spin_unlock(&handler_list_write_lock);
>  			module_put(handler->module);
>  			return -EEXIST;
>  		}
>  	}
> -	rcu_read_unlock();
> 
>  	list_add_rcu(&handler->list, &handler_list);
>  	spin_unlock(&handler_list_write_lock);

Acked-by: Harald Freudenberger <freude@linux.ibm.com>

  reply	other threads:[~2025-09-16 10:51 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-16  4:47 [PATCH v3 00/14] Remove redundant rcu_read_lock/unlock() in spin_lock pengdonglin
2025-09-16  4:47 ` [PATCH v3 01/14] ACPI: APEI: " pengdonglin
2025-09-27  3:22   ` Hanjun Guo
2025-09-28 10:33     ` Rafael J. Wysocki
2025-09-16  4:47 ` [PATCH v3 02/14] drm/i915/gt: " pengdonglin
2025-09-16  4:47 ` [PATCH v3 03/14] fs: aio: " pengdonglin
2025-09-16  4:47 ` [PATCH v3 04/14] nfs: " pengdonglin
2025-09-16  4:47 ` [PATCH v3 05/14] s390/pkey: " pengdonglin
2025-09-16 10:51   ` Harald Freudenberger [this message]
2025-09-16  4:47 ` [PATCH v3 06/14] ipc: " pengdonglin
2025-09-16  4:47 ` [PATCH v3 07/14] yama: " pengdonglin
2025-09-16  4:47 ` [PATCH v3 08/14] cgroup: " pengdonglin
2025-09-16 18:37   ` Tejun Heo
2025-09-16  4:47 ` [PATCH v3 09/14] cgroup/cpuset: " pengdonglin
2025-09-16 18:37   ` Tejun Heo
2025-09-16  4:47 ` [PATCH v3 10/14] wifi: mac80211: " pengdonglin
2025-09-16  4:47 ` [PATCH v3 11/14] net: ncsi: " pengdonglin
2025-09-16  9:41   ` Paul Fertser
2025-09-16  4:47 ` [PATCH v3 12/14] net: amt: " pengdonglin
2025-09-16  4:47 ` [PATCH v3 13/14] net: bonding: " pengdonglin
2025-09-16  4:47 ` [PATCH v3 14/14] wifi: ath9k: " pengdonglin

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