Re: [PATCH net-next 3/4] net: factorize code in kmalloc_reserve()

[Soheil Hassas Yeganeh <soheil@google.com>]

On Thu, Feb 2, 2023 at 1:58 PM Eric Dumazet <edumazet@google.com> wrote:
>
> All kmalloc_reserve() callers have to make the same computation,
> we can factorize them, to prepare following patch in the series.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Acked-by: Soheil Hassas Yeganeh <soheil@google.com>

> ---
>  net/core/skbuff.c | 27 +++++++++++----------------
>  1 file changed, 11 insertions(+), 16 deletions(-)
>
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index a82df5289208d69716e60c5c1f201ec3ca50a258..ae0b2aa1f01e8060cc4fe69137e9bd98e44280cc 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -478,17 +478,20 @@ EXPORT_SYMBOL(napi_build_skb);
>   * may be used. Otherwise, the packet data may be discarded until enough
>   * memory is free
>   */
> -static void *kmalloc_reserve(size_t size, gfp_t flags, int node,
> +static void *kmalloc_reserve(unsigned int *size, gfp_t flags, int node,
>                              bool *pfmemalloc)
>  {
> -       void *obj;
>         bool ret_pfmemalloc = false;
> +       unsigned int obj_size;
> +       void *obj;
>
> +       obj_size = SKB_HEAD_ALIGN(*size);
> +       *size = obj_size = kmalloc_size_roundup(obj_size);
>         /*
>          * Try a regular allocation, when that fails and we're not entitled
>          * to the reserves, fail.
>          */
> -       obj = kmalloc_node_track_caller(size,
> +       obj = kmalloc_node_track_caller(obj_size,
>                                         flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
>                                         node);
>         if (obj || !(gfp_pfmemalloc_allowed(flags)))
> @@ -496,7 +499,7 @@ static void *kmalloc_reserve(size_t size, gfp_t flags, int node,
>
>         /* Try again but now we are using pfmemalloc reserves */
>         ret_pfmemalloc = true;
> -       obj = kmalloc_node_track_caller(size, flags, node);
> +       obj = kmalloc_node_track_caller(obj_size, flags, node);
>
>  out:
>         if (pfmemalloc)
> @@ -557,9 +560,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
>          * aligned memory blocks, unless SLUB/SLAB debug is enabled.
>          * Both skb->head and skb_shared_info are cache line aligned.
>          */
> -       size = SKB_HEAD_ALIGN(size);
> -       size = kmalloc_size_roundup(size);
> -       data = kmalloc_reserve(size, gfp_mask, node, &pfmemalloc);
> +       data = kmalloc_reserve(&size, gfp_mask, node, &pfmemalloc);
>         if (unlikely(!data))
>                 goto nodata;
>         /* kmalloc_size_roundup() might give us more room than requested.
> @@ -1931,9 +1932,7 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
>         if (skb_pfmemalloc(skb))
>                 gfp_mask |= __GFP_MEMALLOC;
>
> -       size = SKB_HEAD_ALIGN(size);
> -       size = kmalloc_size_roundup(size);
> -       data = kmalloc_reserve(size, gfp_mask, NUMA_NO_NODE, NULL);
> +       data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
>         if (!data)
>                 goto nodata;
>         size = SKB_WITH_OVERHEAD(size);
> @@ -6282,9 +6281,7 @@ static int pskb_carve_inside_header(struct sk_buff *skb, const u32 off,
>         if (skb_pfmemalloc(skb))
>                 gfp_mask |= __GFP_MEMALLOC;
>
> -       size = SKB_HEAD_ALIGN(size);
> -       size = kmalloc_size_roundup(size);
> -       data = kmalloc_reserve(size, gfp_mask, NUMA_NO_NODE, NULL);
> +       data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
>         if (!data)
>                 return -ENOMEM;
>         size = SKB_WITH_OVERHEAD(size);
> @@ -6400,9 +6397,7 @@ static int pskb_carve_inside_nonlinear(struct sk_buff *skb, const u32 off,
>         if (skb_pfmemalloc(skb))
>                 gfp_mask |= __GFP_MEMALLOC;
>
> -       size = SKB_HEAD_ALIGN(size);
> -       size = kmalloc_size_roundup(size);
> -       data = kmalloc_reserve(size, gfp_mask, NUMA_NO_NODE, NULL);
> +       data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
>         if (!data)
>                 return -ENOMEM;
>         size = SKB_WITH_OVERHEAD(size);
> --
> 2.39.1.456.gfc5497dd1b-goog
>