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Thu, 01 Feb 2024 12:43:38 +0000 Message-ID: <2abd09d9-eb35-413f-9447-5ecb6e9839ba@suse.de> Date: Thu, 1 Feb 2024 13:43:38 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 04/12] nvmet-fc: defer cleanup using RCU properly Content-Language: en-US To: Daniel Wagner , James Smart Cc: Keith Busch , Christoph Hellwig , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org References: <20240131085112.21668-1-dwagner@suse.de> <20240131085112.21668-5-dwagner@suse.de> From: Hannes Reinecke In-Reply-To: <20240131085112.21668-5-dwagner@suse.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Authentication-Results: smtp-out1.suse.de; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=F4cLai+e; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=SKyiwdm2 X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Spamd-Result: default: False [-4.50 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; XM_UA_NO_VERSION(0.01)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; BAYES_HAM(-3.00)[100.00%]; MIME_GOOD(-0.10)[text/plain]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; NEURAL_HAM_LONG(-1.00)[-1.000]; RCPT_COUNT_FIVE(0.00)[6]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.de:+]; MX_GOOD(-0.01)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:dkim,suse.de:email]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; NEURAL_HAM_SHORT(-0.20)[-1.000]; RCVD_TLS_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[] X-Rspamd-Queue-Id: 6953F21224 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240201_044342_098680_1BE1CBAD X-CRM114-Status: GOOD ( 18.04 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 1/31/24 09:51, Daniel Wagner wrote: > When the target executes a disconnect and the host triggers a reconnect > immediately, the reconnect command still finds an existing association. > > The reconnect crashes later on because nvmet_fc_delete_target_assoc > blindly removes resources while the reconnect code wants to use it. > > To address this, nvmet_fc_find_target_assoc should not be able to > lookup an association which is being removed. The association list > is already under RCU lifetime management, so let's properly use it > and remove the association from the list and wait for a grace period > before cleaning up all. This means we also can drop the RCU management > on the queues, because this is now handled via the association itself. > > A second step split the execution context so that the initial disconnect > command can complete without running the reconnect code in the same > context. As usual, this is done by deferring the ->done to a workqueue. > > Reviewed-by: Christoph Hellwig > Signed-off-by: Daniel Wagner > --- > drivers/nvme/target/fc.c | 83 ++++++++++++++++++---------------------- > 1 file changed, 37 insertions(+), 46 deletions(-) > Reviewed-by: Hannes Reinecke Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), GF: Ivo Totev, Andrew McDonald, Werner Knoblich