On Mon, Mar 22, 2021 at 4:02 PM Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote: > > On Mon, Mar 22, 2021 at 4:57 PM Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote: > > > > On Fri, Mar 19, 2021 at 8:21 PM Andy Shevchenko > > <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote: > > > > > > The decrementation of acpi_device_bus_id->instance_no > > > in acpi_device_del() is incorrect, because it may cause > > > a duplicate instance number to be allocated next time > > > a device with the same acpi_device_bus_id is added. > > > > > > Replace above mentioned approach by using IDA framework. > > ... > > > > + result = ida_simple_get(&acpi_device_bus_id->instance_ida, 0, 255, GFP_KERNEL); > > > > This is ida_alloc_range(ida, start, (end) - 1, gfp), so I think it > > should be 256 above, instead of 255. > > Ah, good catch! > > > > While at it, though, there can be more than 256 CPU devices easily on > > contemporary systems, so I would use a greater number here. Maybe > > 4096 and define a symbol for it? > > I was thinking about it, but there is a problem with the device name, > since it will break a lot of code, What problem is there? > And taking into account that currently we don't change the behaviour > it is good enough per se as a fix. > > That said, we may extend by an additional patch with a logic like this: > > res = ida_get(4096) > if (res < 0) > return res; > if (res >= 256) > use %04x > else > use %02x > > Would it make sense to you? I'm not sure why not to always use %02x ? It doesn't truncate numbers longer than 2 digits AFAICS.
