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    SubjectRe: [PATCH v1 18/29] virtio-mem: factor out calculation of the bit number within the sb_states bitmap
    On Mon, Oct 12, 2020 at 02:53:12PM +0200, David Hildenbrand wrote:
    >The calculation is already complicated enough, let's limit it to one
    >location.
    >
    >Cc: "Michael S. Tsirkin" <mst@redhat.com>
    >Cc: Jason Wang <jasowang@redhat.com>
    >Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
    >Signed-off-by: David Hildenbrand <david@redhat.com>

    Reviewed-by: Wei Yang <richard.weiyang@linux.alibaba.com>

    >---
    > drivers/virtio/virtio_mem.c | 20 +++++++++++++++-----
    > 1 file changed, 15 insertions(+), 5 deletions(-)
    >
    >diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
    >index 2cc497ad8298..73ff6e9ba839 100644
    >--- a/drivers/virtio/virtio_mem.c
    >+++ b/drivers/virtio/virtio_mem.c
    >@@ -327,6 +327,16 @@ static int virtio_mem_sbm_mb_states_prepare_next_mb(struct virtio_mem *vm)
    > _mb_id--) \
    > if (virtio_mem_sbm_get_mb_state(_vm, _mb_id) == _state)
    >
    >+/*
    >+ * Calculate the bit number in the sb_states bitmap for the given subblock
    >+ * inside the given memory block.
    >+ */
    >+static int virtio_mem_sbm_sb_state_bit_nr(struct virtio_mem *vm,
    >+ unsigned long mb_id, int sb_id)
    >+{
    >+ return (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
    >+}
    >+
    > /*
    > * Mark all selected subblocks plugged.
    > *
    >@@ -336,7 +346,7 @@ static void virtio_mem_sbm_set_sb_plugged(struct virtio_mem *vm,
    > unsigned long mb_id, int sb_id,
    > int count)
    > {
    >- const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
    >+ const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
    >
    > __bitmap_set(vm->sbm.sb_states, bit, count);
    > }
    >@@ -350,7 +360,7 @@ static void virtio_mem_sbm_set_sb_unplugged(struct virtio_mem *vm,
    > unsigned long mb_id, int sb_id,
    > int count)
    > {
    >- const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
    >+ const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
    >
    > __bitmap_clear(vm->sbm.sb_states, bit, count);
    > }
    >@@ -362,7 +372,7 @@ static bool virtio_mem_sbm_test_sb_plugged(struct virtio_mem *vm,
    > unsigned long mb_id, int sb_id,
    > int count)
    > {
    >- const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
    >+ const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
    >
    > if (count == 1)
    > return test_bit(bit, vm->sbm.sb_states);
    >@@ -379,7 +389,7 @@ static bool virtio_mem_sbm_test_sb_unplugged(struct virtio_mem *vm,
    > unsigned long mb_id, int sb_id,
    > int count)
    > {
    >- const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
    >+ 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) >=
    >@@ -393,7 +403,7 @@ static bool virtio_mem_sbm_test_sb_unplugged(struct virtio_mem *vm,
    > static int virtio_mem_sbm_first_unplugged_sb(struct virtio_mem *vm,
    > unsigned long mb_id)
    > {
    >- const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb;
    >+ const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, 0);
    >
    > return find_next_zero_bit(vm->sbm.sb_states,
    > bit + vm->nb_sb_per_mb, bit) - bit;
    >--
    >2.26.2

    --
    Wei Yang
    Help you, Help me

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