On Wed, Dec 05, 2018 at 02:49:39PM +0800, Xin Long wrote: > Without the support for the total_nr_elements's growing or shrinking > dynamically, flex_array is not that 'flexible'. Like when users want > to change the size, they have to redo flex_array_alloc and copy all > the elements from the old to the new one. The worse thing is every > element's memory gets changed. > > To implement flex_array_resize based on current code, the difficult > thing is to process the size border of FLEX_ARRAY_BASE_BYTES_LEFT, > where the base data memory may change to an array for the 2nd level > data memory for growing, likewise for shrinking. > > To make this part easier, we separate the base data memory and define > FLEX_ARRAY_BASE_SIZE as a same value of FLEX_ARRAY_PART_SIZE, as Neil > suggested. When new size is crossing the border, the base memory is > allocated as the array for the 2nd level data memory and its part[0] > is pointed to the old base memory, and do the opposite for shrinking. > > But it doesn't do any memory allocation or shrinking for elements in > flex_array_resize, as which should be done by flex_array_prealloc or > flex_array_shrink called by users. No memory leaks can be caused by > that. > > SCTP has benefited a lot from flex_array_resize() for managing its > stream memory so far. > > Xin Long (3): > flex_array: make FLEX_ARRAY_BASE_SIZE the same value of > FLEX_ARRAY_PART_SIZE > flex_array: support flex_array_resize > sctp: fa_resize sctp stream instead of redo fa_alloc > > include/linux/flex_array.h | 40 ++++++++++----------- > lib/flex_array.c | 73 ++++++++++++++++++++++++++++++++++++-- > net/sctp/stream.c | 87 +++++++++++++++++++++------------------------- > 3 files changed, 130 insertions(+), 70 deletions(-) > > -- > 2.1.0 > > Series Acked-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
