On 09/21/2016 12:23 PM, zijun_hu wrote: > From: zijun_hu <zijun...@htc.com> > > correct a few logic error for __insert_vmap_area() since the else > if condition is always true and meaningless > > in order to fix this issue, if vmap_area inserted is lower than one > on rbtree then walk around left branch; if higher then right branch > otherwise intersects with the other then BUG_ON() is triggered > > Signed-off-by: zijun_hu <zijun...@htc.com> i give more explanation to the intent of my change any comments is welcome > --- > mm/vmalloc.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 91f44e7..cc6ecd6 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -321,10 +321,10 @@ static void __insert_vmap_area(struct vmap_area *va) > > parent = *p; > tmp_va = rb_entry(parent, struct vmap_area, rb_node); > - if (va->va_start < tmp_va->va_end) > - p = &(*p)->rb_left; > - else if (va->va_end > tmp_va->va_start) > - p = &(*p)->rb_right; this else if condition is always true and meaningless as long as there are no zero sized vamp_area due to the following expression va->va_end > va->va_start >= tmp_va->va_end > tmp_va->va_start
> + if (va->va_end <= tmp_va->va_start) > + p = &parent->rb_left; if the vamp_area to be inserted is lower than that on the rbtree then we walk around the left branch of the node given consider va->va_end == tmp_va->va_start as legal case which represent two neighbor areas tightly BTW, the available range of a vmap area include the start boundary not the end, namely, [start, end) > + else if (va->va_start >= tmp_va->va_end) > + p = &parent->rb_right; if the vamp_area to be inserted is higher than that on the rbtree then we walk around the right branch of the node given > else > BUG(); this indicate the vamp_area to be inserted have intersects with that on the rbtree then we remain the BUG() logic > } >
