netdev - Re: [PATCH net 0/3] net: add support for flex_array_resize in flex

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Date:   Wed, 5 Dec 2018 07:34:08 -0500
From:   Neil Horman <nhorman@...driver.com>
To:     Xin Long <lucien.xin@...il.com>
Cc:     network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org,
        davem@...emloft.net,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Dave Hansen <dave@...ux.vnet.ibm.com>,
        Konstantin Khorenko <khorenko@...tuozzo.com>
Subject: Re: [PATCH net 0/3] net: add support for flex_array_resize in
 flex_array

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@...driver.com>