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Wed, 2 Dec 2020 15:56:27 +0000 (GMT) Subject: Re: [PATCH v2 06/17] ibmvfc: add handlers to drain and complete Sub-CRQ responses To: Tyrel Datwyler , james.bottomley@hansenpartnership.com Cc: martin.petersen@oracle.com, linux-scsi@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, brking@linux.ibm.com References: <20201202005329.4538-1-tyreld@linux.ibm.com> <20201202005329.4538-7-tyreld@linux.ibm.com> From: Brian King Message-ID: <8a3c6a0b-ebf5-581a-e3e9-748c09373d92@linux.vnet.ibm.com> Date: Wed, 2 Dec 2020 09:56:26 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201202005329.4538-7-tyreld@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312,18.0.737 definitions=2020-12-02_08:2020-11-30,2020-12-02 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 bulkscore=0 phishscore=0 clxscore=1015 adultscore=0 priorityscore=1501 suspectscore=2 mlxlogscore=999 impostorscore=0 mlxscore=0 malwarescore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2012020093 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/1/20 6:53 PM, Tyrel Datwyler wrote: > +static void ibmvfc_handle_scrq(struct ibmvfc_crq *crq, struct ibmvfc_host *vhost) > +{ > + struct ibmvfc_event *evt = (struct ibmvfc_event *)be64_to_cpu(crq->ioba); > + unsigned long flags; > + > + switch (crq->valid) { > + case IBMVFC_CRQ_CMD_RSP: > + break; > + case IBMVFC_CRQ_XPORT_EVENT: > + return; > + default: > + dev_err(vhost->dev, "Got and invalid message type 0x%02x\n", crq->valid); > + return; > + } > + > + /* The only kind of payload CRQs we should get are responses to > + * things we send. Make sure this response is to something we > + * actually sent > + */ > + if (unlikely(!ibmvfc_valid_event(&vhost->pool, evt))) { > + dev_err(vhost->dev, "Returned correlation_token 0x%08llx is invalid!\n", > + crq->ioba); > + return; > + } > + > + if (unlikely(atomic_read(&evt->free))) { > + dev_err(vhost->dev, "Received duplicate correlation_token 0x%08llx!\n", > + crq->ioba); > + return; > + } > + > + spin_lock_irqsave(vhost->host->host_lock, flags); > + del_timer(&evt->timer); > + list_del(&evt->queue); > + ibmvfc_trc_end(evt); Another thought here... If you are going through ibmvfc_purge_requests at the same time as this code, you could check the free bit above, then have ibmvfc_purge_requests put the event on the free queue and call scsi_done, then you come down and get the host lock here, remove the command from the free list, and call the done function again, which could result in a double completion to the scsi layer. I think you need to grab the host lock before you check the free bit to avoid this race. > + spin_unlock_irqrestore(vhost->host->host_lock, flags); > + evt->done(evt); > +} > + -- Brian King Power Linux I/O IBM Linux Technology Center