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Wed, 12 Jun 2024 11:07:30 GMT Received: from smtpav01.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 53FF45807A; Wed, 12 Jun 2024 11:07:28 +0000 (GMT) Received: from smtpav01.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 79E385806B; Wed, 12 Jun 2024 11:07:25 +0000 (GMT) Received: from [9.43.104.93] (unknown [9.43.104.93]) by smtpav01.wdc07v.mail.ibm.com (Postfix) with ESMTP; Wed, 12 Jun 2024 11:07:25 +0000 (GMT) Message-ID: <15192c9d-ce45-4dbc-bdbb-752cdfd4e663@linux.ibm.com> Date: Wed, 12 Jun 2024 16:37:23 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/1] nvme-pci : Fix EEH failure on ppc after subsystem reset To: Maurizio Lombardi Cc: kbusch@kernel.org, linux-nvme@lists.infradead.org, hch@lst.de, sagi@grimberg.me, gjoyce@linux.ibm.com, axboe@fb.com References: <20240604091523.1422027-1-nilay@linux.ibm.com> <20240604091523.1422027-2-nilay@linux.ibm.com> Content-Language: en-US From: Nilay Shroff In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: ZwVwC0O3uFc1K0LRX84VwNPnWBKVzplB X-Proofpoint-ORIG-GUID: wWlgI_2vIgWHtf0rnRQRDKhEmYRM8BMC X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.28.16 definitions=2024-06-12_06,2024-06-12_01,2024-05-17_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 spamscore=0 suspectscore=0 adultscore=0 malwarescore=0 priorityscore=1501 clxscore=1015 impostorscore=0 phishscore=0 lowpriorityscore=0 bulkscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2405170001 definitions=main-2406120079 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240612_040818_781357_61AA3D0F X-CRM114-Status: GOOD ( 21.44 ) 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 6/10/24 18:02, Maurizio Lombardi wrote: > út 4. 6. 2024 v 11:16 odesílatel Nilay Shroff napsal: >> >> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c >> index f5d150c62955..afb8419566a9 100644 >> --- a/drivers/nvme/host/core.c >> +++ b/drivers/nvme/host/core.c >> @@ -562,6 +562,7 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl, >> switch (old_state) { >> case NVME_CTRL_NEW: >> case NVME_CTRL_LIVE: >> + case NVME_CTRL_CONNECTING: >> changed = true; >> fallthrough; >> default: > > Side note: > > I believe this could fix a race condition in the nvme-tcp driver. > Some time ago we received a kernel dump where the controller was > flagged as NVME_CTRL_LIVE but the sockets were marked as TCP_CLOSED, > the kernel was hanging into io_work. > It might be possible that the socket's nvme_tcp_error_recovery > callback was executed while the ctrl was still marked as > NVME_CTRL_CONNECTING, nvme_change_ctrl_state() doesn't allow a > reconnecting controller to switch to the resetting state and therefore > nvme_tcp_error_recovery() simply returns without triggering an error > recovery. > > nvme_tcp_setup_ctrl() then moves the ctrl to the LIVE state, but with > closed tcp sockets. > > I guess that this change would fix the possible race condition, even > if I am not completely sure what could happen in case of a race > between nvme_tcp_setup_ctrl() and the error recovery code. > I think for your case you shall consider using nvme_wait_reset() before queuing error recovery work. For instance, it could be done something like below assuming that all callers of nvme_tcp_error_recovery() are allowed to sleep (not fully tested) : static void nvme_tcp_error_recovery(struct nvme_ctrl *ctrl) { if (!nvme_wait_reset(ctrl)) return; dev_warn(ctrl->device, "starting error recovery\n"); queue_work(nvme_reset_wq, &to_tcp_ctrl(ctrl)->err_work); } The nvme_wait_reset() shall wait until the nvme_tcp_setup_ctrl() finish its work and then the tcp error recovery work would be initiated. Thanks, --Nilay