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Wed, 19 Mar 2025 15:47:21 -0700 (PDT) Message-ID: <4937c9f8-fbc7-46d4-a14f-262a0244f1f0@gmail.com> Date: Wed, 19 Mar 2025 15:47:20 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 10/18] nvmet-fcloop: allocate/free fcloop_lsreq directly To: Daniel Wagner , James Smart , Christoph Hellwig , Sagi Grimberg , Chaitanya Kulkarni Cc: Hannes Reinecke , Keith Busch , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org References: <20250318-nvmet-fcloop-v3-0-05fec0fc02f6@kernel.org> <20250318-nvmet-fcloop-v3-10-05fec0fc02f6@kernel.org> Content-Language: en-US From: James Smart In-Reply-To: <20250318-nvmet-fcloop-v3-10-05fec0fc02f6@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/18/2025 3:40 AM, Daniel Wagner wrote: > fcloop depends on the host or the target to allocate the fcloop_lsreq > object. This means that the lifetime of the fcloop_lsreq is tied to > either the host or the target. Consequently, the host or the target must > cooperate during shutdown. > > Unfortunately, this approach does not work well when the target forces a > shutdown, as there are dependencies that are difficult to resolve in a > clean way. ok - although I'm guessing you'll trading one set of problems for another. > > The simplest solution is to decouple the lifetime of the fcloop_lsreq > object by managing them directly within fcloop. Since this is not a > performance-critical path and only a small number of LS objects are used > during setup and cleanup, it does not significantly impact performance > to allocate them during normal operation. ok > > Signed-off-by: Daniel Wagner > --- > drivers/nvme/target/fcloop.c | 53 +++++++++++++++++++++++++++++--------------- > 1 file changed, 35 insertions(+), 18 deletions(-) > > diff --git a/drivers/nvme/target/fcloop.c b/drivers/nvme/target/fcloop.c > index 06f42da6a0335c53ae319133119d057aab12e07e..537fc6533a4cf5d39855cf850b82af739eeb3056 100644 > --- a/drivers/nvme/target/fcloop.c > +++ b/drivers/nvme/target/fcloop.c > @@ -342,6 +342,7 @@ fcloop_rport_lsrqst_work(struct work_struct *work) > * callee may free memory containing tls_req. > * do not reference lsreq after this. > */ > + kfree(tls_req); > > spin_lock(&rport->lock); > } > @@ -353,10 +354,13 @@ fcloop_h2t_ls_req(struct nvme_fc_local_port *localport, > struct nvme_fc_remote_port *remoteport, > struct nvmefc_ls_req *lsreq) > { > - struct fcloop_lsreq *tls_req = lsreq->private; > struct fcloop_rport *rport = remoteport->private; > + struct fcloop_lsreq *tls_req; > int ret = 0; > > + tls_req = kmalloc(sizeof(*tls_req), GFP_KERNEL); > + if (!tls_req) > + return -ENOMEM; > tls_req->lsreq = lsreq; > INIT_LIST_HEAD(&tls_req->ls_list); > > @@ -387,19 +391,23 @@ fcloop_h2t_xmt_ls_rsp(struct nvmet_fc_target_port *targetport, > struct nvme_fc_remote_port *remoteport = tport->remoteport; > struct fcloop_rport *rport; > > + > + if (!remoteport) { > + kfree(tls_req); > + return -ECONNREFUSED; > + } > + don't do this - this is not a path the lldd would generate. > memcpy(lsreq->rspaddr, lsrsp->rspbuf, > ((lsreq->rsplen < lsrsp->rsplen) ? > lsreq->rsplen : lsrsp->rsplen)); > > lsrsp->done(lsrsp); This done() call should always be made regardless of the remoteport presence. instead, put the check here if (!remoteport) { kfree(tls_req); return 0; } > > - if (remoteport) { > - rport = remoteport->private; > - spin_lock(&rport->lock); > - list_add_tail(&tls_req->ls_list, &rport->ls_list); > - spin_unlock(&rport->lock); > - queue_work(nvmet_wq, &rport->ls_work); > - } > + rport = remoteport->private; > + spin_lock(&rport->lock); > + list_add_tail(&tls_req->ls_list, &rport->ls_list); > + spin_unlock(&rport->lock); > + queue_work(nvmet_wq, &rport->ls_work); this is just an indentation style - whichever way works. > > return 0; > } > @@ -426,6 +434,7 @@ fcloop_tport_lsrqst_work(struct work_struct *work) > * callee may free memory containing tls_req. > * do not reference lsreq after this. > */ > + kfree(tls_req); > > spin_lock(&tport->lock); > } > @@ -436,8 +445,8 @@ static int > fcloop_t2h_ls_req(struct nvmet_fc_target_port *targetport, void *hosthandle, > struct nvmefc_ls_req *lsreq) > { > - struct fcloop_lsreq *tls_req = lsreq->private; > struct fcloop_tport *tport = targetport->private; > + struct fcloop_lsreq *tls_req; > int ret = 0; > > /* > @@ -445,6 +454,10 @@ fcloop_t2h_ls_req(struct nvmet_fc_target_port *targetport, void *hosthandle, > * hosthandle ignored as fcloop currently is > * 1:1 tgtport vs remoteport > */ > + > + tls_req = kmalloc(sizeof(*tls_req), GFP_KERNEL); > + if (!tls_req) > + return -ENOMEM; > tls_req->lsreq = lsreq; > INIT_LIST_HEAD(&tls_req->ls_list); > > @@ -461,6 +474,9 @@ fcloop_t2h_ls_req(struct nvmet_fc_target_port *targetport, void *hosthandle, > ret = nvme_fc_rcv_ls_req(tport->remoteport, &tls_req->ls_rsp, > lsreq->rqstaddr, lsreq->rqstlen); > > + if (ret) > + kfree(tls_req); > + > return ret; > } > > @@ -475,18 +491,21 @@ fcloop_t2h_xmt_ls_rsp(struct nvme_fc_local_port *localport, > struct nvmet_fc_target_port *targetport = rport->targetport; > struct fcloop_tport *tport; > > + if (!targetport) { > + kfree(tls_req); > + return -ECONNREFUSED; > + } > + same here - don't do this - this is not a path the lldd would generate. > memcpy(lsreq->rspaddr, lsrsp->rspbuf, > ((lsreq->rsplen < lsrsp->rsplen) ? > lsreq->rsplen : lsrsp->rsplen)); > lsrsp->done(lsrsp); > Same for this done(). instead, put the check here if (!targetport) { kfree(tls_req); return 0; } > - if (targetport) { > - tport = targetport->private; > - spin_lock(&tport->lock); > - list_add_tail(&tport->ls_list, &tls_req->ls_list); > - spin_unlock(&tport->lock); > - queue_work(nvmet_wq, &tport->ls_work); > - } > + tport = targetport->private; > + spin_lock(&tport->lock); > + list_add_tail(&tport->ls_list, &tls_req->ls_list); > + spin_unlock(&tport->lock); > + queue_work(nvmet_wq, &tport->ls_work); > > return 0; > } > @@ -1129,7 +1148,6 @@ static struct nvme_fc_port_template fctemplate = { > /* sizes of additional private data for data structures */ > .local_priv_sz = sizeof(struct fcloop_lport_priv), > .remote_priv_sz = sizeof(struct fcloop_rport), > - .lsrqst_priv_sz = sizeof(struct fcloop_lsreq), > .fcprqst_priv_sz = sizeof(struct fcloop_ini_fcpreq), > }; > > @@ -1152,7 +1170,6 @@ static struct nvmet_fc_target_template tgttemplate = { > .target_features = 0, > /* sizes of additional private data for data structures */ > .target_priv_sz = sizeof(struct fcloop_tport), > - .lsrqst_priv_sz = sizeof(struct fcloop_lsreq), > }; > > static ssize_t > -- james