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Tue, 6 May 2025 06:36:10 +0000 (GMT) Message-ID: Date: Tue, 6 May 2025 12:06:09 +0530 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V5 21/25] block: move elv_register[unregister]_queue out of elevator_lock To: Ming Lei , Jens Axboe , linux-block@vger.kernel.org Cc: Shinichiro Kawasaki , =?UTF-8?Q?Thomas_Hellstr=C3=B6m?= , Christoph Hellwig , Hannes Reinecke References: <20250505141805.2751237-1-ming.lei@redhat.com> <20250505141805.2751237-22-ming.lei@redhat.com> Content-Language: en-US From: Nilay Shroff In-Reply-To: <20250505141805.2751237-22-ming.lei@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=Up9jN/wB c=1 sm=1 tr=0 ts=6819addf cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=dt9VzEwgFbYA:10 a=20KFwNOVAAAA:8 a=VnNF1IyMAAAA:8 a=H82auua0CvPxHtOQ3OUA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: OwR_bHb_Wvy8c9fuiqwl5yHQ_UtY_XJp X-Proofpoint-GUID: OwR_bHb_Wvy8c9fuiqwl5yHQ_UtY_XJp X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNTA2MDA2MSBTYWx0ZWRfX8qgXW+GteIvI Q9Gn9NEKsTg+g7/kaiv5EIPfKxJCODcozS/NhtrAHmM9f3A2ANGOLDuRRvIaXTtfVFFhUPNl2Lo fFKll2rDM2VgiZc6Jvody2axReWkCRmkHsyxkOyQ7NgF42RRsJAKFPVOYep3WBqBg4ISml67HUK h1xSGQuo85DK+CxSTCgzVA0HCZcUGmH/MKX5SjgX5/kKXtnA//7WmR+Ahc3mPt+2Xdp+2Ddxf0v Xx17sjIgqOL4hNRmp8fQfHBIYkwXXSVqX3vigyC30GX3pjeUk80FHxptduqM4ceMPt/LROFY1ZK JrYaVrADBkBFdGOlgZmCvLGTtTuCd0zWgUc0CzMW93IpQuAlWQ2hcRgC7UTgrX2xxpfllAXckTV JKwy6yGFihFWxMjYzaBdvNLfjvE0A88zZFxZxAtibxJZiCFqQWW9GjIkn6B/sQuc5J0F2VFb X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.0.736,FMLib:17.12.80.40 definitions=2025-05-06_03,2025-05-05_01,2025-02-21_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 spamscore=0 phishscore=0 bulkscore=0 lowpriorityscore=0 mlxscore=0 impostorscore=0 suspectscore=0 adultscore=0 priorityscore=1501 clxscore=1015 malwarescore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2504070000 definitions=main-2505060061 On 5/5/25 7:47 PM, Ming Lei wrote: > Move elv_register[unregister]_queue out of ->elevator_lock & queue freezing, > so we can kill many lockdep warnings. > > elv_register[unregister]_queue() is serialized, and just dealing with sysfs/ > debugfs things, no need to be done with queue frozen: > > - when it is called from adding disk, elevator switch isn't possible > because ->queue_kobj isn't added yet > > - when it is called from deleting disk, disable_elv_switch() is > responsible for preventing new elevator switch and draining old > elevator switch. > > - when it is called from blk_mq_update_nr_hw_queues(), adding/removing > disk and elevator switch can't be allowed or in-progress > > With this change, elevator's ->exit() is called before calling > elv_unregister_queue, then user may call into ->show()/store() of elevator's > sysfs attributes, and we have covered this issue by adding `ELEVATOR_FLAG_DYNG`. > > For blk-mq debugfs, hctx->sched_tags is always checked with ->elevator_lock by > debugfs code, meantime hctx->sched_tags is updated with ->elevator_lock, so > there isn't such issue. > > Reviewed-by: Hannes Reinecke > Signed-off-by: Ming Lei Looks good to me: Reviewed-by : Nilay Shroff