Encapsulate find_next_bit and find_next_zero_bit calls into helpers to verify if a range of subblocks is entirely plugged or unplugged.
This improves readability as requested by the TODO comments in the source code. Validation confirms the change is binary-neutral on ARM64, with the generated instructions remaining identical. Suggested-by: David Hildenbrand <[email protected]> Signed-off-by: Luan Haickel Araujo <[email protected]> --- Hi David, This is my first patch contribution to the Linux kernel, following up on your TODO notes in virtio_mem.c. As part of my learning process (LFX 103), I verified the change in a QEMU (KVM) environment with test_bitmap. I also compared the generated assembly on ARM64 and it remains identical, confirming the helpers are binary-neutral as expected. I noticed these helpers could also be useful in include/linux/bitmap.h in the future. If you think it makes sense to move them there, I'd be happy to work on that in a next step. Looking forward to your feedback. Luan. drivers/virtio/virtio_mem.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c index 48051e9e98ab..e94e30af3a5d 100644 --- a/drivers/virtio/virtio_mem.c +++ b/drivers/virtio/virtio_mem.c @@ -538,6 +538,22 @@ static void virtio_mem_sbm_set_sb_unplugged(struct virtio_mem *vm, __bitmap_clear(vm->sbm.sb_states, bit, count); } +static inline bool bitmap_test_range_all_set(const unsigned long *map, + unsigned int start, unsigned int nbits) +{ + unsigned int next_zero_bit = find_next_zero_bit(map, start + nbits, start); + + return next_zero_bit >= start + nbits; +} + +static inline bool bitmap_test_range_all_zero(const unsigned long *map, + unsigned int start, unsigned int nbits) +{ + unsigned int next_set_bit = find_next_bit(map, start + nbits, start); + + return next_set_bit >= start + nbits; +} + /* * Test if all selected subblocks are plugged. */ @@ -550,9 +566,7 @@ static bool virtio_mem_sbm_test_sb_plugged(struct virtio_mem *vm, if (count == 1) return test_bit(bit, vm->sbm.sb_states); - /* TODO: Helper similar to bitmap_set() */ - return find_next_zero_bit(vm->sbm.sb_states, bit + count, bit) >= - bit + count; + return bitmap_test_range_all_set(vm->sbm.sb_states, bit, count); } /* @@ -564,9 +578,7 @@ static bool virtio_mem_sbm_test_sb_unplugged(struct virtio_mem *vm, { const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id); - /* TODO: Helper similar to bitmap_set() */ - return find_next_bit(vm->sbm.sb_states, bit + count, bit) >= - bit + count; + return bitmap_test_range_all_zero(vm->sbm.sb_states, bit, count); } /* -- 2.53.0
