Re: [PATCH 10/17] netvm: Allow skb allocation to use PFMEMALLOCreserves

From: Sebastian Andrzej Siewior
Date: Thu Jun 21 2012 - 12:09:23 EST


On Wed, Jun 20, 2012 at 12:44:05PM +0100, Mel Gorman wrote:
> index b534a1b..61c951f 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -505,6 +506,15 @@ struct sk_buff {
> #include <linux/slab.h>
>
>
> +#define SKB_ALLOC_FCLONE 0x01
> +#define SKB_ALLOC_RX 0x02
> +
> +/* Returns true if the skb was allocated from PFMEMALLOC reserves */
> +static inline bool skb_pfmemalloc(struct sk_buff *skb)
> +{
> + return unlikely(skb->pfmemalloc);
> +}
> +
> /*
> * skb might have a dst pointer attached, refcounted or not.
> * _skb_refdst low order bit is set if refcount was _not_ taken
> @@ -568,7 +578,7 @@ extern bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 1d6ecc8..9a58dcc 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -839,6 +900,13 @@ static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
> skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
> }
>
> +static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
> +{
> + if (skb_pfmemalloc((struct sk_buff *)skb))
> + return SKB_ALLOC_RX;
> + return 0;
> +}
> +
> /**
> * skb_copy - create private copy of an sk_buff
> * @skb: buffer to copy

If merge this chunk

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 6510a5d..2acfec9 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -510,7 +510,7 @@ struct sk_buff {
#define SKB_ALLOC_RX 0x02

/* Returns true if the skb was allocated from PFMEMALLOC reserves */
-static inline bool skb_pfmemalloc(struct sk_buff *skb)
+static inline bool skb_pfmemalloc(const struct sk_buff *skb)
{
return unlikely(skb->pfmemalloc);
}
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index c44ab68..6ce94b5 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -852,7 +852,7 @@ static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)

static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
{
- if (skb_pfmemalloc((struct sk_buff *)skb))
+ if (skb_pfmemalloc(skb))
return SKB_ALLOC_RX;
return 0;
}


Then you should be able to drop the case in skb_alloc_rx_flag() without adding
a warning.

Sebastian
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