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author | Jason A. Donenfeld <Jason@zx2c4.com> | 2020-01-08 16:59:02 -0500 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-01-23 15:49:56 +0100 |
commit | 8e6f5a1d3bd462ff54cdb86f2938bfaa4223ccc9 (patch) | |
tree | 17b45bd4ccfdec3592f0f1a3becc3d62948804b8 /include/linux/skbuff.h | |
parent | 4d1d3dddcb3f26000e66cd0a9b8b16f7c2eb41bb (diff) | |
download | linux-stable-8e6f5a1d3bd462ff54cdb86f2938bfaa4223ccc9.tar.gz linux-stable-8e6f5a1d3bd462ff54cdb86f2938bfaa4223ccc9.tar.bz2 linux-stable-8e6f5a1d3bd462ff54cdb86f2938bfaa4223ccc9.zip |
net: introduce skb_list_walk_safe for skb segment walking
commit dcfea72e79b0aa7a057c8f6024169d86a1bbc84b upstream.
As part of the continual effort to remove direct usage of skb->next and
skb->prev, this patch adds a helper for iterating through the
singly-linked variant of skb lists, which are used for lists of GSO
packet. The name "skb_list_..." has been chosen to match the existing
function, "kfree_skb_list, which also operates on these singly-linked
lists, and the "..._walk_safe" part is the same idiom as elsewhere in
the kernel.
This patch removes the helper from wireguard and puts it into
linux/skbuff.h, while making it a bit more robust for general usage. In
particular, parenthesis are added around the macro argument usage, and it
now accounts for trying to iterate through an already-null skb pointer,
which will simply run the iteration zero times. This latter enhancement
means it can be used to replace both do { ... } while and while (...)
open-coded idioms.
This should take care of these three possible usages, which match all
current methods of iterations.
skb_list_walk_safe(segs, skb, next) { ... }
skb_list_walk_safe(skb, skb, next) { ... }
skb_list_walk_safe(segs, skb, segs) { ... }
Gcc appears to generate efficient code for each of these.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[ Just the skbuff.h changes for backporting - gregkh]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/skbuff.h')
-rw-r--r-- | include/linux/skbuff.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 703ce71caeac..881038a0e1c8 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1363,6 +1363,11 @@ static inline void skb_mark_not_on_list(struct sk_buff *skb) skb->next = NULL; } +/* Iterate through singly-linked GSO fragments of an skb. */ +#define skb_list_walk_safe(first, skb, next) \ + for ((skb) = (first), (next) = (skb) ? (skb)->next : NULL; (skb); \ + (skb) = (next), (next) = (skb) ? (skb)->next : NULL) + static inline void skb_list_del_init(struct sk_buff *skb) { __list_del_entry(&skb->list); |