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Tue, 16 Sep 2025 10:51:04 +0000 (GMT) MIME-Version: 1.0 Date: Tue, 16 Sep 2025 12:51:03 +0200 From: Harald Freudenberger To: pengdonglin 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 , Vasily Gorbik , Alexander Gordeev , pengdonglin Subject: Re: [PATCH v3 05/14] s390/pkey: Remove redundant rcu_read_lock/unlock() in spin_lock Mail-Reply-To: freude@linux.ibm.com In-Reply-To: <20250916044735.2316171-6-dolinux.peng@gmail.com> References: <20250916044735.2316171-1-dolinux.peng@gmail.com> <20250916044735.2316171-6-dolinux.peng@gmail.com> Message-ID: <31be6bb6541bb3e338e3025ac9e8fce5@linux.ibm.com> X-Sender: freude@linux.ibm.com Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: dUB5GxZDVKC_6J2Ylb023C_3mzK49UHc X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwOTE1MDA4NiBTYWx0ZWRfX5K5HvLPe748s 1a0iccxe5DzHqpq2HHVExtQN3K3dDZAHmx+plczsOrZBuez8PS/bGeKlwxmdko1vp27MiJETJTG rWBkahKjm6E+Lehe9W5AsUAlfhXLzBCKZl91u4s5pKGLTilBgre1vFNiCO4KLvO9XrWU1Caav6A LP5y7FEjU/NnADi5ucPQYwViKT2GmRSmRBhcRXXpZEfspZ5l5uxEmXVcbW4As4eHjzGuflsj31H fsacgfENVa2S7hh4yS1XXPBx2rL5+dQv2gYhPIFTz7huQ8NQh9IyA9t8ZyRl7UxTDbk1vmK6jmT k/dl/Zv55pKlRrfw9Ym17kI1XWuEyzglymXJjQwZlfbaExngRAMTnR8i/K+0vtUxACA7W2YSZzh NNpGuSjP X-Proofpoint-ORIG-GUID: okqK8s0OaduvH8SS01anEhfn0Ac3dkSd X-Authority-Analysis: v=2.4 cv=UJ7dHDfy c=1 sm=1 tr=0 ts=68c9411d cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=kj9zAlcOel0A:10 a=yJojWOMRYYMA:10 a=IeNN-m2dAAAA:8 a=VnNF1IyMAAAA:8 a=pGLkceISAAAA:8 a=6zuzY4jPHNdFWWqqfRgA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1117,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-09-16_02,2025-09-12_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 bulkscore=0 impostorscore=0 spamscore=0 priorityscore=1501 clxscore=1011 suspectscore=0 phishscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2509150086 X-Mailman-Approved-At: Tue, 16 Sep 2025 14:55:20 +0000 X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: freude@linux.ibm.com Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On 2025-09-16 06:47, pengdonglin wrote: > From: pengdonglin > > 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 > Cc: Holger Dengler > Cc: Vasily Gorbik > Cc: Alexander Gordeev > Signed-off-by: pengdonglin > Signed-off-by: pengdonglin > --- > 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