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Message-ID: <alpine.DEB.2.02.1405021528510.19956@tomh.mtv.corp.google.com>
Date: Fri, 2 May 2014 16:29:18 -0700 (PDT)
From: Tom Herbert <therbert@...gle.com>
To: davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 5/8 v4] net: Generalize checksum_init functions
Create a general __skb_checksum_validate function (actually a
macro) to subsume the various checksum_init functions. This
function can either init the checksum, or do the full validation
(logically checksum_init+skb_check_complete)-- a flag specifies
if full vaidation is performed. Also, there is a flag to the function
to indicate that zero checksums are allowed (to support optional
UDP checksums).
Added several stub functions for calling __skb_checksum_validate.
Signed-off-by: Tom Herbert <therbert@...gle.com>
---
include/linux/skbuff.h | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 93 insertions(+)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 08074a8..3ca0dda 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2741,6 +2741,99 @@ static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
0 : __skb_checksum_complete(skb);
}
+/* Check if we need to perform checksum complete validation.
+ *
+ * Returns true if checksum complete is needed, false otherwise
+ * (either checksum is unnecessary or zero checksum is allowed).
+ */
+static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
+ bool zero_okay,
+ __sum16 check)
+{
+ if (skb_csum_unnecessary(skb)) {
+ return false;
+ } else if (zero_okay && !check) {
+ skb->ip_summed = CHECKSUM_UNNECESSARY;
+ return false;
+ }
+
+ return true;
+}
+
+/* For small packets <= CHECKSUM_BREAK peform checksum complete directly
+ * in checksum_init.
+ */
+#define CHECKSUM_BREAK 76
+
+/* Validate (init) checksum based on checksum complete.
+ *
+ * Return values:
+ * 0: checksum is validated or try to in skb_checksum_complete. In the latter
+ * case the ip_summed will not be CHECKSUM_UNNECESSARY and the pseudo
+ * checksum is stored in skb->csum for use in __skb_checksum_complete
+ * non-zero: value of invalid checksum
+ *
+ */
+static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,
+ bool complete,
+ __wsum psum)
+{
+ if (skb->ip_summed == CHECKSUM_COMPLETE) {
+ if (!csum_fold(csum_add(psum, skb->csum))) {
+ skb->ip_summed = CHECKSUM_UNNECESSARY;
+ return 0;
+ }
+ }
+
+ skb->csum = psum;
+
+ if (complete || skb->len <= CHECKSUM_BREAK)
+ return __skb_checksum_complete(skb);
+
+ return 0;
+}
+
+static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto)
+{
+ return 0;
+}
+
+/* Perform checksum validate (init). Note that this is a macro since we only
+ * want to calculate the pseudo header which is an input function if necessary.
+ * First we try to validate without any computation (checksum unnecessary) and
+ * then calculate based on checksum complete calling the function to compute
+ * pseudo header.
+ *
+ * Return values:
+ * 0: checksum is validated or try to in skb_checksum_complete
+ * non-zero: value of invalid checksum
+ */
+#define __skb_checksum_validate(skb, proto, complete, \
+ zero_okay, check, compute_pseudo) \
+({ \
+ __sum16 __ret = 0; \
+ if (__skb_checksum_validate_needed(skb, zero_okay, check)) \
+ __ret = __skb_checksum_validate_complete(skb, \
+ complete, compute_pseudo(skb, proto)); \
+ __ret; \
+})
+
+#define skb_checksum_init(skb, proto, compute_pseudo) \
+ __skb_checksum_validate(skb, proto, false, false, 0, compute_pseudo)
+
+#define skb_checksum_init_zero_check(skb, proto, check, compute_pseudo) \
+ __skb_checksum_validate(skb, proto, false, true, check, compute_pseudo)
+
+#define skb_checksum_validate(skb, proto, compute_pseudo) \
+ __skb_checksum_validate(skb, proto, true, false, 0, compute_pseudo)
+
+#define skb_checksum_validate_zero_check(skb, proto, check, \
+ compute_pseudo) \
+ __skb_checksum_validate_(skb, proto, true, true, check, compute_pseudo)
+
+#define skb_checksum_simple_validate(skb) \
+ __skb_checksum_validate(skb, 0, true, false, 0, null_compute_pseudo)
+
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
void nf_conntrack_destroy(struct nf_conntrack *nfct);
static inline void nf_conntrack_put(struct nf_conntrack *nfct)
--
1.9.1.423.g4596e3a
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