a7fe30736a46d203b74e9fb2df3fb4e1d94222bc ("batman-adv: Add function to calculate crc32c for the skb payload") introduced a function that walked through the three different socket buffer classes to compute the crc32 for an skb. This function is affected by many changes to the sk_buff structure in future. This can be avoided by using the sequential read functions to access blocks transparently.

Reported-by: Martin Hundebøll martin@hundeboll.net Reported-by: Marek Lindner lindner_marek@yahoo.de Signed-off-by: Sven Eckelmann sven@narfation.org --- compat.h | 35 ----------------------------------- main.c | 31 +++++++++++++------------------ main.h | 2 +- 3 files changed, 14 insertions(+), 54 deletions(-)

diff --git a/compat.h b/compat.h index 83befd1..be685aa 100644 --- a/compat.h +++ b/compat.h @@ -37,9 +37,6 @@

#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 31)

-#define skb_walk_frags(skb, iter) \ - for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next) - #define __compat__module_param_call(p1, p2, p3, p4, p5, p6, p7) \ __module_param_call(p1, p2, p3, p4, p5, p7)

@@ -81,18 +78,6 @@ #endif /* < KERNEL_VERSION(2, 6, 35) */

-#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 37) - -#define kmap_atomic(p) kmap_atomic(p, KM_SKB_DATA_SOFTIRQ) - -#ifdef kunmap_atomic -#undef kunmap_atomic -#endif -#define kunmap_atomic(x, arg...) do { pagefault_enable(); } while (0) - -#endif /* < KERNEL_VERSION(2, 6, 37) */ - - #if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 36)

#define __rcu @@ -160,26 +145,6 @@ static inline void skb_reset_mac_len(struct sk_buff *skb) #endif /* < KERNEL_VERSION(3, 0, 0) */

-#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 2, 0) - -static inline struct page *skb_frag_page(const skb_frag_t *frag) -{ - return frag->page; -} - -static inline void *skb_frag_address(const skb_frag_t *frag) -{ - return page_address(skb_frag_page(frag)) + frag->page_offset; -} - -static inline unsigned int skb_frag_size(const skb_frag_t *frag) -{ - return frag->size; -} - -#endif /* < KERNEL_VERSION(3, 2, 0) */ - - #if LINUX_VERSION_CODE < KERNEL_VERSION(3, 4, 0)

static inline void eth_hw_addr_random(struct net_device *dev) diff --git a/main.c b/main.c index 2b1123d..253e240 100644 --- a/main.c +++ b/main.c @@ -444,29 +444,24 @@ int batadv_compat_seq_print_text(struct seq_file *seq, void *offset) * payload_ptr must always point to an address in the skb head buffer and not to * a fragment. */ -__be32 batadv_skb_crc32(const struct sk_buff *skb, u8 *payload_ptr) +__be32 batadv_skb_crc32(struct sk_buff *skb, u8 *payload_ptr) { u32 crc = 0; - struct sk_buff *iter; - size_t skip_len, read_len; - const skb_frag_t *f; - u8 *vaddr; - int i; + unsigned int from; + unsigned int to = skb->len; + struct skb_seq_state st; + const u8 *data; + unsigned int len; + unsigned int consumed = 0;

- skip_len = payload_ptr - skb->data; - read_len = skb_headlen(skb) - skip_len; - if (read_len) - crc = crc32c(crc, payload_ptr, read_len); + from = (unsigned int)(payload_ptr - skb->data);

- for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { - f = &skb_shinfo(skb)->frags[i]; - vaddr = kmap_atomic(skb_frag_page(f)); - crc = crc32c(crc, vaddr + f->page_offset, skb_frag_size(f)); - kunmap_atomic(vaddr); + skb_prepare_seq_read(skb, from, to, &st); + while ((len = skb_seq_read(consumed, &data, &st)) != 0) { + crc = crc32c(crc, data, len); + consumed += len; } - - skb_walk_frags(skb, iter) - crc = crc32c(crc, iter->data, skb_headlen(iter)); + skb_abort_seq_read(&st);

return htonl(crc); } diff --git a/main.h b/main.h index e147261..3321173 100644 --- a/main.h +++ b/main.h @@ -177,7 +177,7 @@ int batadv_algo_register(struct batadv_algo_ops *bat_algo_ops); int batadv_algo_select(struct batadv_priv *bat_priv, char *name); int batadv_algo_seq_print_text(struct seq_file *seq, void *offset); int batadv_compat_seq_print_text(struct seq_file *seq, void *offset); -__be32 batadv_skb_crc32(const struct sk_buff *skb, u8 *payload_ptr); +__be32 batadv_skb_crc32(struct sk_buff *skb, u8 *payload_ptr);

/** * enum batadv_dbg_level - available log levels