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Wed, 31 Jan 2024 08:51:28 +0000 (UTC) Received: from dovecot-director2.suse.de ([10.150.64.162]) by imap2.dmz-prg2.suse.org with ESMTPSA id dtunLxAKumWfHAAAn2gu4w (envelope-from ); Wed, 31 Jan 2024 08:51:28 +0000 From: Daniel Wagner To: James Smart Cc: Keith Busch , Christoph Hellwig , Hannes Reinecke , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, Daniel Wagner Subject: [PATCH v5 12/12] nvmet-fc: use RCU list iterator for assoc_list Date: Wed, 31 Jan 2024 09:51:12 +0100 Message-ID: <20240131085112.21668-13-dwagner@suse.de> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240131085112.21668-1-dwagner@suse.de> References: <20240131085112.21668-1-dwagner@suse.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Authentication-Results: smtp-out2.suse.de; none X-Spam-Level: ** X-Spam-Score: 2.26 X-Spamd-Result: default: False [2.26 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; R_MISSING_CHARSET(2.50)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.10)[text/plain]; BROKEN_CONTENT_TYPE(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_RATELIMIT(0.00)[to_ip_from(RL7u6ok1g4a6hhe6aduz96x8er)]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; RCPT_COUNT_SEVEN(0.00)[7]; MID_CONTAINS_FROM(1.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_ALL(0.00)[]; BAYES_HAM(-1.44)[91.26%] X-Spam-Flag: NO Content-Type: text/plain; charset="utf-8" The assoc_list is a RCU protected list, thus use the RCU flavor of list functions. Let's use this opportunity and refactor this code and move the lookup into a helper and give it a descriptive name. Signed-off-by: Daniel Wagner Reviewed-by: Christoph Hellwig --- drivers/nvme/target/fc.c | 34 ++++++++++++++++++++++------------ 1 file changed, 22 insertions(+), 12 deletions(-) diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c index 671d096745a5..fd229f310c93 100644 --- a/drivers/nvme/target/fc.c +++ b/drivers/nvme/target/fc.c @@ -1114,14 +1114,27 @@ nvmet_fc_schedule_delete_assoc(struct nvmet_fc_tgt_= assoc *assoc) queue_work(nvmet_wq, &assoc->del_work); } =20 +static bool +nvmet_fc_assoc_exits(struct nvmet_fc_tgtport *tgtport, u64 association_id) +{ + struct nvmet_fc_tgt_assoc *a; + + list_for_each_entry_rcu(a, &tgtport->assoc_list, a_list) { + if (association_id =3D=3D a->association_id) + return true; + } + + return false; +} + static struct nvmet_fc_tgt_assoc * nvmet_fc_alloc_target_assoc(struct nvmet_fc_tgtport *tgtport, void *hostha= ndle) { - struct nvmet_fc_tgt_assoc *assoc, *tmpassoc; + struct nvmet_fc_tgt_assoc *assoc; unsigned long flags; + bool done; u64 ran; int idx; - bool needrandom =3D true; =20 if (!tgtport->pe) return NULL; @@ -1145,24 +1158,21 @@ nvmet_fc_alloc_target_assoc(struct nvmet_fc_tgtport= *tgtport, void *hosthandle) INIT_WORK(&assoc->del_work, nvmet_fc_delete_assoc_work); atomic_set(&assoc->terminating, 0); =20 - while (needrandom) { + done =3D false; + do { get_random_bytes(&ran, sizeof(ran) - BYTES_FOR_QID); ran =3D ran << BYTES_FOR_QID_SHIFT; =20 spin_lock_irqsave(&tgtport->lock, flags); - needrandom =3D false; - list_for_each_entry(tmpassoc, &tgtport->assoc_list, a_list) { - if (ran =3D=3D tmpassoc->association_id) { - needrandom =3D true; - break; - } - } - if (!needrandom) { + rcu_read_lock(); + if (!nvmet_fc_assoc_exits(tgtport, ran)) { assoc->association_id =3D ran; list_add_tail_rcu(&assoc->a_list, &tgtport->assoc_list); + done =3D true; } + rcu_read_unlock(); spin_unlock_irqrestore(&tgtport->lock, flags); - } + } while (!done); =20 return assoc; =20 --=20 2.43.0