linux.git/tools/testing/selftests/vfio/lib/sysfs.c, branch master Linux kernel source tree vfio: selftests: Introduce a sysfs lib 2026-05-20T17:54:10+00:00 Raghavendra Rao Ananta rananta@google.com 2026-05-05T21:28:33+00:00 c5db77a035e1291e2c9b488073c28b441e5e44f3 Introduce a sysfs library to handle the common reads/writes to the PCI sysfs files, for example, getting the total number of VFs supported by the device via /sys/bus/pci/devices/$BDF/sriov_totalvfs. The library will be used in the upcoming test patch to configure the VFs for a given PF device. Since readlink() is quite commonly used in the lib, introduce and use readlink_safe() to take care of potential buffer overrun errors and to safely terminate the buffer with '\0'. Opportunistically, move vfio_pci_get_group_from_dev() to this library as it falls under the same bucket. Rename it to sysfs_iommu_group_get() to align with other function names. Signed-off-by: Raghavendra Rao Ananta <rananta@google.com> Reviewed-by: Vipin Sharma <vipinsh@google.com> Reviewed-by: David Matlack <dmatlack@google.com> Tested-by: David Matlack <dmatlack@google.com> Link: https://lore.kernel.org/r/20260505212838.1698034-4-rananta@google.com Signed-off-by: Alex Williamson <alex@shazbot.org> 
Introduce a sysfs library to handle the common reads/writes to the
PCI sysfs files, for example, getting the total number of VFs supported
by the device via /sys/bus/pci/devices/$BDF/sriov_totalvfs. The library
will be used in the upcoming test patch to configure the VFs for a given
PF device.

Since readlink() is quite commonly used in the lib, introduce and use
readlink_safe() to take care of potential buffer overrun errors and to
safely terminate the buffer with '\0'.

Opportunistically, move vfio_pci_get_group_from_dev() to this library as
it falls under the same bucket. Rename it to sysfs_iommu_group_get() to
align with other function names.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Vipin Sharma <vipinsh@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Tested-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20260505212838.1698034-4-rananta@google.com
Signed-off-by: Alex Williamson <alex@shazbot.org>