Messages in this thread | | | Subject | Re: [PATH v2] scsi: scsi_dh_rdac: Avoid crash during rdac_bus_attach | From | yebin <> | Date | Thu, 22 Jul 2021 21:09:43 +0800 |
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On 2021/1/13 14:31, Ye Bin wrote: > We get follow BUG_ON when rdac scan: > [595952.944297] kernel BUG at drivers/scsi/device_handler/scsi_dh_rdac.c:427! > [595952.951143] Internal error: Oops - BUG: 0 [#1] SMP > ...... > [595953.251065] Call trace: > [595953.259054] check_ownership+0xb0/0x118 > [595953.269794] rdac_bus_attach+0x1f0/0x4b0 > [595953.273787] scsi_dh_handler_attach+0x3c/0xe8 > [595953.278211] scsi_dh_add_device+0xc4/0xe8 > [595953.282291] scsi_sysfs_add_sdev+0x8c/0x2a8 > [595953.286544] scsi_probe_and_add_lun+0x9fc/0xd00 > [595953.291142] __scsi_scan_target+0x598/0x630 > [595953.295395] scsi_scan_target+0x120/0x130 > [595953.299481] fc_user_scan+0x1a0/0x1c0 [scsi_transport_fc] > [595953.304944] store_scan+0xb0/0x108 > [595953.308420] dev_attr_store+0x44/0x60 > [595953.312160] sysfs_kf_write+0x58/0x80 > [595953.315893] kernfs_fop_write+0xe8/0x1f0 > [595953.319888] __vfs_write+0x60/0x190 > [595953.323448] vfs_write+0xac/0x1c0 > [595953.326836] ksys_write+0x74/0xf0 > [595953.330221] __arm64_sys_write+0x24/0x30 > > BUG_ON code is in check_ownership: > list_for_each_entry_rcu(tmp, &h->ctlr->dh_list, node) { > /* h->sdev should always be valid */ > BUG_ON(!tmp->sdev); > tmp->sdev->access_state = access_state; > } > rdac_bus_attach > initialize_controller > list_add_rcu(&h->node, &h->ctlr->dh_list); > h->sdev = sdev; > rdac_bus_detach > list_del_rcu(&h->node); > h->sdev = NULL; > > Test as follow steps: > (1) Find IO error, remove disk; > (2) Insert disk back; > (3) trigger scan disk; > > There is race between rdac_bus_attach and rdac_bus_detach, maybe access > rdac_dh_data which h->sdev has been set NULL when process rdac attach. And also > find that "h->sdev" set value after add list, this may lead to reference NULL ptr. > > Signed-off-by: Ye Bin <yebin10@huawei.com> > --- > drivers/scsi/device_handler/scsi_dh_rdac.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/scsi/device_handler/scsi_dh_rdac.c b/drivers/scsi/device_handler/scsi_dh_rdac.c > index 5efc959493ec..85a71bafaea7 100644 > --- a/drivers/scsi/device_handler/scsi_dh_rdac.c > +++ b/drivers/scsi/device_handler/scsi_dh_rdac.c > @@ -453,8 +453,8 @@ static int initialize_controller(struct scsi_device *sdev, > if (!h->ctlr) > err = SCSI_DH_RES_TEMP_UNAVAIL; > else { > - list_add_rcu(&h->node, &h->ctlr->dh_list); > h->sdev = sdev; > + list_add_rcu(&h->node, &h->ctlr->dh_list); > } > spin_unlock(&list_lock); > err = SCSI_DH_OK; > @@ -778,11 +778,11 @@ static void rdac_bus_detach( struct scsi_device *sdev ) > spin_lock(&list_lock); > if (h->ctlr) { > list_del_rcu(&h->node); > - h->sdev = NULL; > kref_put(&h->ctlr->kref, release_controller); > } > spin_unlock(&list_lock); > sdev->handler_data = NULL; > + synchronize_rcu(); > kfree(h); > } > ping ...
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