Hi, On 12/9/19 12:32 PM, Moritz Müller wrote: > In some cases floppy disks are being indexed, even though no actual > device exists. In our case this was caused by the CMOS-RAM having a few > peculiar bits. This caused a non-existent floppy disk of the type 13 (in > our case) to be registered as an possibly mountable device, even though > it could not be mounted by any user. > > We believe this to be an instance of this bug: > > https://bugzilla.kernel.org/show_bug.cgi?id=13486 > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/384579 > > This patch adds the option FLOPPY_ALLOW_UNKNOWN_TYPES to prevent the > additional check that fixed the issue on our reference system, and > increases the startup time of affected systems by over a minute. > > Co-developed-by: Philip K. <philip@xxxxxxxxxxxx> > Signed-off-by: Philip K. <philip@xxxxxxxxxxxx> > Signed-off-by: Moritz Müller <moritzm.mueller@xxxxxxxxx> Thank you for the patch! Have you tested your patch with FLOPPY_ALLOW_UNKNOWN_TYPES and without FLOPPY_ALLOW_UNKNOWN_TYPES? I will answer about motivation for this change in V2 branch of the patch. > --- > drivers/block/Kconfig | 10 ++++++++++ > drivers/block/floppy.c | 6 ++++++ > 2 files changed, 16 insertions(+) > > diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig > index 1bb8ec575352..9e6b32c50b67 100644 > --- a/drivers/block/Kconfig > +++ b/drivers/block/Kconfig > @@ -72,6 +72,16 @@ config AMIGA_Z2RAM > To compile this driver as a module, choose M here: the > module will be called z2ram. > > +config FLOPPY_ALLOW_UNKNOWN_TYPES > + bool "Allow floppy disks of unknown type to be registered." > + default n > + help > + Select this option if you want the Kernel to register floppy > + disks of an unknown type. > + > + This should usually not be enabled, because of cases where the > + system falsely recognizes a non-existent floppy disk as mountable. > + > config CDROM > tristate > select BLK_SCSI_REQUEST > diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c > index 485865fd0412..9439444d46d0 100644 > --- a/drivers/block/floppy.c > +++ b/drivers/block/floppy.c > @@ -3949,7 +3949,11 @@ static void __init config_types(void) > } else > allowed_drive_mask &= ~(1 << drive); > } else { > +#ifdef CONFIG_FLOPPY_ALLOW_UNKNOWN_TYPES > params = &default_drive_params[0].params; > +#else > + params = UDP; > +#endif > snprintf(temparea, sizeof(temparea), > "unknown type %d (usb?)", type); > name = temparea; Maybe just skip the else branch completely here? This will omit snprintf, following if (name) block and UDP update. +#ifdef CONFIG_FLOPPY_ALLOW_UNKNOWN_TYPES params = &default_drive_params[0].params; snprintf(temparea, sizeof(temparea), "unknown type %d (usb?)", type); name = temparea; +#else + continue; +#endif > @@ -4518,7 +4520,10 @@ static bool floppy_available(int drive) > return false; > if (fdc_state[FDC(drive)].version == FDC_NONE) > return false; > +#ifndef CONFIG_FLOPPY_ALLOW_UNKNOWN_TYPES > + if (UDP->cmos >= ARRAY_SIZE(default_drive_params)) > + return false; > +#endif > return true; > } > > Thanks, Denis
