On 04/03/2013 02:04 AM, Mikulas Patocka wrote: > Hi > > This fixes BZ 912245 and 902595. > > Mikulas > > --- > > dm-mpath: do not change SCSI device handler > > This patch prevents the multipath target from changing the device handler. > This fixes a kernel crash that can happen when changing the device > handler. > > When we reload a multipath device, there are two instances of the > multipath target - the first instance that is active and the second > instance that is being constructed with "ctr" method. > > If the multipath constructor finds out that the device is using a > different device handler, it detaches the existing handler and attaches a > new handler. However, the first instance of the multipath target still > exists and processes requests. If the first instance sends some > path-management request with scsi_dh_activate and the second instance > detaches the device handler while the path-management request is in > flight, a crash happens. The reason for the crash is that the endio > routine for the path-management request is working with structures that > were freed when the handler was detached. > > There is no practical need to change device handlers on an active device, > so this patch disables it. > > Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> > NACK. This kills multipath startup when scsi_dh_* modules are already loaded. After boot scsi_dh_* modules might already be loaded without multipath running. Multipath might have defined other hardware handlers in the configuration file, and will re-attach them on startup. With this patch multipath cannot configure the devices properly and will abort. Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
