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Thu, 3 Sep 2026 18:43:36 +0000 (GMT) Received: from d (unknown [9.16.41.19]) by smtpav06.dal12v.mail.ibm.com (Postfix) with ESMTPS; Thu, 3 Sep 2026 18:43:36 +0000 (GMT) From: Dave Marquardt To: sashiko-reviews@lists.linux.dev Cc: linux-scsi@vger.kernel.org Subject: Re: [PATCH v7 6/8] scsi: ibmvfc: extend channel registration and deregistration for async subq In-Reply-To: <20260831223431.2F4341F000E9@smtp.kernel.org> References: <20260831-ibmvfc-fpin-support-v7-0-77d0b9809080@linux.ibm.com> <20260831-ibmvfc-fpin-support-v7-6-77d0b9809080@linux.ibm.com> <20260831223431.2F4341F000E9@smtp.kernel.org> Date: Thu, 03 Sep 2026 13:43:36 -0500 Message-ID: <8733vq5g6f.fsf@linux.ibm.com> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTAzMDE2MiBTYWx0ZWRfX2qP3PaEyX4Kd tJ5492BHBpDhuwlYft5cEcaMVGDh5OLTIAzeZR+5HaQbhYqDTCmcIWr2Z1FOg/07RayUnrpQ0PT ZKSbptU5xBa9x9s/SCuVbwwKB+eaMIPEvtWIPifVup6zoftDSV78DDefGEAWqIiXb41GK+HQhgy YppNwK/wLChVboN32xzH84FYTF20N+FN1T+urHMQ0K3P+0FLK9qx3vJQvBwX8eRSLZOuBW7VS+K q+KFRe0h+o0Fb2kE8kUmn64SmFF6HXm4bNtmsJ6BC9HpwzIcK7Y3GGHJr8uzi8jrn8dad23lYPt tVggMZ//LGc8jNEDxfaY3VJpEDjUHdhB5dARsVRg2qeEHwnSaB5uEr0cWTm60PgI15hH9wjVNbS h5YHBC4yx6sxXuQ3PgIrij5L2VdRea5OQgyBDgWBs3UGc7PXpcm8TQ8Xm1eGefXBWxpP9yEODMp /EVssti3UgEx+9U975Q== X-Proofpoint-ORIG-GUID: nNdcDsrwh3BYkpSl0Me4-2RE9uEkTfSD X-Authority-Analysis: v=2.4 cv=CNgamxrD c=1 sm=1 tr=0 ts=6a99bfda cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VwQbUJbxAAAA:8 a=cFIKowR6tQ2XqRsfE8cA:9 X-Proofpoint-GUID: nNdcDsrwh3BYkpSl0Me4-2RE9uEkTfSD X-Proofpoint-Spam-Info: AW1haW4tMjYwOTAzMDE2MiBTYWx0ZWRfX/pkxUQ/dnUbf y72es/9NxzRyJiv8z9jS2AofViI6CBpZdDPrbG27/faNyt0zRGWxirYpwf9Bx9olLpzLoMqZZ1r nVI3TGMBAz3jPDEe6kjKQcMPt2Gmodk= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-03_05,2026-09-03_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 bulkscore=0 suspectscore=0 phishscore=0 lowpriorityscore=0 priorityscore=1501 clxscore=1015 impostorscore=0 adultscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2609030162 sashiko-bot@kernel.org writes: >> diff --git a/drivers/scsi/ibmvscsi/ibmvfc-core.c b/drivers/scsi/ibmvscsi/ibmvfc-core.c >> --- a/drivers/scsi/ibmvscsi/ibmvfc-core.c >> +++ b/drivers/scsi/ibmvscsi/ibmvfc-core.c >> @@ -4409,7 +4409,7 @@ static void ibmvfc_drain_async_subq(struct ibmvfc_queue *scrq) >> * @scrq_instance: async subq >> * >> **/ >> -static irqreturn_t __maybe_unused ibmvfc_interrupt_async_subq(int irq, void *scrq_instance) >> +static irqreturn_t ibmvfc_interrupt_async_subq(int irq, void *scrq_instance) >> { >> struct ibmvfc_queue *scrq = (struct ibmvfc_queue *)scrq_instance; >> > > [Severity: High] > Now that the async sub-CRQ handler is enabled by this patch, can its > execution race with target teardown or host reset? > > In drivers/scsi/ibmvscsi/ibmvfc-core.c, the interrupt handler calls: > ibmvfc_interrupt_async_subq() -> ibmvfc_drain_async_subq() -> > ibmvfc_handle_async(). > > The ibmvfc_handle_async() function expects to hold vhost->host->host_lock, > but this call chain only holds scrq->q_lock. Consequently, it iterates over > and modifies vhost->scsi_scrqs.targets without the proper lock. > > Could this lockless list traversal cause a use-after-free or data corruption > when handling dynamic async events sent by the hypervisor? > > [ ... ] This is fixed in the next revision of patch 5, where the host lock is acquired and released in ibmvfc_handle_async. >> @@ -6825,36 +6841,49 @@ static int ibmvfc_register_channel(struct ibmvfc_host *vhost, > [ ... ] >> rc = request_irq(scrq->irq, scrq->handler, 0, scrq->name, scrq); >> >> if (rc) { >> - dev_err(dev, "Couldn't register sub-crq[%d] irq\n", index); >> + if (!is_async) >> + dev_err(dev, "Couldn't register sub-crq[%d] irq\n", index); >> + else >> + dev_err(dev, "Couldn't register async sub-crq irq\n"); >> irq_dispose_mapping(scrq->irq); >> goto irq_failed; >> } > > [Severity: Medium] > This is a pre-existing issue, but does leaving scrq->irq populated with a > stale value after irq_dispose_mapping() cause a kernel warning during > teardown? > > If request_irq() fails in ibmvfc_register_channel(), the error path calls > irq_dispose_mapping(scrq->irq) but does not clear the irq field to 0. Later, > when ibmvfc_deregister_channel() is unconditionally called for the async > sub-CRQ during teardown, it might call free_irq(scrq->irq, scrq) on this > stale mapping ID (or on 0 if it was never registered). > > Should scrq->irq be explicitly cleared to 0 in this error path to prevent > invalid IRQ descriptor warnings? Agreed, this is a bug. I will add a separate patch to fix this issue. -Dave