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Tue, 3 Mar 2026 21:45:21 +0000 (GMT) Message-ID: <77b2b44d7101d55151c8e9852ce41783205ed987.camel@linux.ibm.com> Subject: Re: [PATCH 1/1] scsi: virtio_scsi: move INIT_WORK calls to virtscsi_init From: Eric Farman To: Joshua Daley , linux-scsi@vger.kernel.org Cc: linux-kernel@vger.kernel.org, virtualization@lists.linux.dev, mst@redhat.com, jasowang@redhat.com, pbonzini@redhat.com, stefanha@redhat.com, eperezma@redhat.com, James.Bottomley@HansenPartnership.com, martin.petersen@oracle.com, mjrosato@linux.ibm.com, frankja@linux.ibm.com Date: Tue, 03 Mar 2026 16:45:20 -0500 In-Reply-To: <20260226204345.1904786-2-jdaley@linux.ibm.com> References: <20260226204345.1904786-1-jdaley@linux.ibm.com> <20260226204345.1904786-2-jdaley@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.3 (3.58.3-1.fc43) Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=Rp/I7SmK c=1 sm=1 tr=0 ts=69a75674 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=OoLDd18DN7KcugGRceQA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzAzMDE3OCBTYWx0ZWRfX9UV+9tKVerIM k10Vj2ibRJ8eww0ccLke/e0k0hZswnhSv7Dtw/F/rqVEjA3f+LOI5SnCldZe+nTAq+cWReKtMb4 KjrpWkPpznsGS5fNGk1yXarMN+lnSUpjegM1kHo8lJQSn88KaWaJQwj45fTtEZnKb7W5DBc/SPI PNlXp1X2DAGnLx0YDgn1OgLyZT/fsqKJPGRsv4g41cFePt4/Vt/R+Z++kU47TjEem0nPamikORv kKgSLqSIksZW2awxqAVxqbSHZiYdZVhj8sST8ttrduRR6xrExTVxUEynL1+dtSCEpAl28As7Emq ZvdvKRTV7GgeHAyPXJ3R0yIr0NDsh6Ukqzxu3c4c/TCLOzzas6ZT+HxGWP+qBaJ1jGoQOhvh5sz ddIds/XKb9rf2Wdf9mHv97lwz0Fp1nIcyPlTTXxdGR4PpnDT994XcDDhncWyu8hE8KELMsHv3kz HcZentz7j5rknyj+1Hg== X-Proofpoint-GUID: M9-a5C4YNMae_nxfA-v5ZeCBMvDe9zWq X-Proofpoint-ORIG-GUID: M9-a5C4YNMae_nxfA-v5ZeCBMvDe9zWq X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-03_03,2026-03-03_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 priorityscore=1501 spamscore=0 phishscore=0 adultscore=0 bulkscore=0 clxscore=1011 impostorscore=0 malwarescore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2602130000 definitions=main-2603030178 On Thu, 2026-02-26 at 21:43 +0100, Joshua Daley wrote: > The last step of virtscsi_handle_event is to call virtscsi_kick_event, > which calls INIT_WORK on it's own work item. INIT_WORK resets the > work item's data bits to 0. >=20 > If this occurs while the work item is being flushed by > cancel_work_sync, then kernel/workqueue.c/work_offqd_enable triggers a > kernel warning, as it expects the "disable" bit to be 1: >=20 > [ 21.450115] workqueue: work disable count underflowed > [ 21.450117] WARNING: CPU: 1 PID: 56 at kernel/workqueue.c:4328 enable_= work+0x10a/0x120 > ... > [ 21.450171] Call Trace: > [ 21.450173] [<000003db2e5bdc3e>] enable_work+0x10e/0x120 > [ 21.450176] ([<000003db2e5bdc3a>] enable_work+0x10a/0x120) > [ 21.450178] [<000003db2e5bdd86>] cancel_work_sync+0x86/0xa0 > [ 21.450181] [<000003daae97d9e4>] virtscsi_remove+0xb4/0xd0 [virtio_sc= si] > [ 21.450184] [<000003db2ef3b5ca>] virtio_dev_remove+0x6a/0xd0 > [ 21.450186] [<000003db2ef9106c>] device_release_driver_internal+0x1ac= /0x260 > [ 21.450190] [<000003db2ef8edc8>] bus_remove_device+0xf8/0x190 > [ 21.450192] [<000003db2ef88d72>] device_del+0x142/0x340 > [ 21.450194] [<000003db2ef88fa0>] device_unregister+0x30/0xa0 > [ 21.450196] [<000003db2ef3b2fa>] unregister_virtio_device+0x2a/0x40 >=20 > This warning may occur if a controller is detached immediately > following a disk detach. >=20 > Move the INIT_WORK call to prevent this. Don't re-init event list > work items in virtscsi_kick_event, init them only once in > virtscsi_init instead. >=20 > Signed-off-by: Joshua Daley The fact that the INIT_WORK points to virtscsi_handle_event(), which itself= calls virtscsi_kick_event() and re-inits the workqueue struct today, does seem od= d. Moving this to _init, as part of the _probe() process, seems correct to me. One nit below, but FW= IW: Reviewed-by: Eric Farman Tested-by: Eric Farman > --- > drivers/scsi/virtio_scsi.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) >=20 > diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c > index 0ed8558dad72..173092931df6 100644 > --- a/drivers/scsi/virtio_scsi.c > +++ b/drivers/scsi/virtio_scsi.c > @@ -242,7 +242,6 @@ static int virtscsi_kick_event(struct virtio_scsi *vs= csi, Just before this hunk is a prototype for virtscsi_handle_event(), since it = was previously used in this function but defined afterwards. I suspect it can be removed now? > struct scatterlist sg; > unsigned long flags; > =20 > - INIT_WORK(&event_node->work, virtscsi_handle_event); > sg_init_one(&sg, event_node->event, sizeof(struct virtio_scsi_event)); > =20 > spin_lock_irqsave(&vscsi->event_vq.vq_lock, flags); > @@ -898,6 +897,11 @@ static int virtscsi_init(struct virtio_device *vdev, > virtscsi_config_set(vdev, cdb_size, VIRTIO_SCSI_CDB_SIZE); > virtscsi_config_set(vdev, sense_size, VIRTIO_SCSI_SENSE_SIZE); > =20 > + if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) { > + for (i =3D 0; i < VIRTIO_SCSI_EVENT_LEN; i++) > + INIT_WORK(&vscsi->event_list[i].work, virtscsi_handle_event); > + } > + > err =3D 0; > =20 > out: