On Sun, Jan 29, 2023 at 09:13:55AM +0800, Yu Kuai wrote: > Hi, Greg > > 在 2023/01/28 18:45, Greg KH 写道: > > > diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c > > > index cac7c902cf70..a22109cdb8ef 100644 > > > --- a/drivers/scsi/scsi_sysfs.c > > > +++ b/drivers/scsi/scsi_sysfs.c > > > @@ -1535,9 +1535,7 @@ static void __scsi_remove_target(struct scsi_target *starget) > > > if (sdev->channel != starget->channel || > > > sdev->id != starget->id) > > > continue; > > > - if (sdev->sdev_state == SDEV_DEL || > > > - sdev->sdev_state == SDEV_CANCEL || > > > - !get_device(&sdev->sdev_gendev)) > > > + if (!get_device_unless_zero(&sdev->sdev_gendev)) > > > > If sdev_gendev is 0 here, the object is gone and you are working with > > memory that is already freed so something is _VERY_ wrong. > > In fact, this patch will work: > > In __scsi_remove_target(), 'host_lock' is held to protect iterating > siblings, and object will wait for this lock in > scsi_device_dev_release() to remove siblings. Hence sdev will not be > freed untill the lock is released. Then you got lucky, as that is not how a reference counted object should be working (i.e. the reference dropped to 0 and it still be kept alive.) Please fix up the scsi logic here, don't abuse the reference count code. thanks, greg k-h
