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gro: Fix remcsum offload to deal with frags in GRO
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The remote checksum offload GRO did not consider the case that frag0
might be in use. This patch fixes that by accessing headers using the
skb_gro functions and not saving offsets relative to skb->head.

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Tom Herbert authored and David S. Miller committed Aug 23, 2015
1 parent 9a873c7 commit b7fe10e
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Showing 3 changed files with 53 additions and 42 deletions.
23 changes: 9 additions & 14 deletions drivers/net/vxlan.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -519,10 +519,10 @@ static struct vxlanhdr *vxlan_gro_remcsum(struct sk_buff *skb,
u32 data, struct gro_remcsum *grc,
bool nopartial)
{
size_t start, offset, plen;
size_t start, offset;

if (skb->remcsum_offload)
return NULL;
return vh;

if (!NAPI_GRO_CB(skb)->csum_valid)
return NULL;
Expand All @@ -532,17 +532,8 @@ static struct vxlanhdr *vxlan_gro_remcsum(struct sk_buff *skb,
offsetof(struct udphdr, check) :
offsetof(struct tcphdr, check));

plen = hdrlen + offset + sizeof(u16);

/* Pull checksum that will be written */
if (skb_gro_header_hard(skb, off + plen)) {
vh = skb_gro_header_slow(skb, off + plen, off);
if (!vh)
return NULL;
}

skb_gro_remcsum_process(skb, (void *)vh + hdrlen,
start, offset, grc, nopartial);
vh = skb_gro_remcsum_process(skb, (void *)vh, off, hdrlen,
start, offset, grc, nopartial);

skb->remcsum_offload = 1;

Expand Down Expand Up @@ -573,7 +564,6 @@ static struct sk_buff **vxlan_gro_receive(struct sk_buff **head,
goto out;
}

skb_gro_pull(skb, sizeof(struct vxlanhdr)); /* pull vxlan header */
skb_gro_postpull_rcsum(skb, vh, sizeof(struct vxlanhdr));

flags = ntohl(vh->vx_flags);
Expand All @@ -588,6 +578,8 @@ static struct sk_buff **vxlan_gro_receive(struct sk_buff **head,
goto out;
}

skb_gro_pull(skb, sizeof(struct vxlanhdr)); /* pull vxlan header */

flush = 0;

for (p = *head; p; p = p->next) {
Expand Down Expand Up @@ -1110,6 +1102,9 @@ static struct vxlanhdr *vxlan_remcsum(struct sk_buff *skb, struct vxlanhdr *vh,
{
size_t start, offset, plen;

if (skb->remcsum_offload)
return vh;

start = (data & VXLAN_RCO_MASK) << VXLAN_RCO_SHIFT;
offset = start + ((data & VXLAN_RCO_UDP) ?
offsetof(struct udphdr, check) :
Expand Down
44 changes: 32 additions & 12 deletions include/linux/netdevice.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2311,8 +2311,7 @@ __sum16 __skb_gro_checksum_complete(struct sk_buff *skb);

static inline bool skb_at_gro_remcsum_start(struct sk_buff *skb)
{
return (NAPI_GRO_CB(skb)->gro_remcsum_start - skb_headroom(skb) ==
skb_gro_offset(skb));
return (NAPI_GRO_CB(skb)->gro_remcsum_start == skb_gro_offset(skb));
}

static inline bool __skb_gro_checksum_validate_needed(struct sk_buff *skb,
Expand Down Expand Up @@ -2408,37 +2407,58 @@ static inline void skb_gro_remcsum_init(struct gro_remcsum *grc)
grc->delta = 0;
}

static inline void skb_gro_remcsum_process(struct sk_buff *skb, void *ptr,
int start, int offset,
struct gro_remcsum *grc,
bool nopartial)
static inline void *skb_gro_remcsum_process(struct sk_buff *skb, void *ptr,
unsigned int off, size_t hdrlen,
int start, int offset,
struct gro_remcsum *grc,
bool nopartial)
{
__wsum delta;
size_t plen = hdrlen + max_t(size_t, offset + sizeof(u16), start);

BUG_ON(!NAPI_GRO_CB(skb)->csum_valid);

if (!nopartial) {
NAPI_GRO_CB(skb)->gro_remcsum_start =
((unsigned char *)ptr + start) - skb->head;
return;
NAPI_GRO_CB(skb)->gro_remcsum_start = off + hdrlen + start;
return ptr;
}

ptr = skb_gro_header_fast(skb, off);
if (skb_gro_header_hard(skb, off + plen)) {
ptr = skb_gro_header_slow(skb, off + plen, off);
if (!ptr)
return NULL;
}

delta = remcsum_adjust(ptr, NAPI_GRO_CB(skb)->csum, start, offset);
delta = remcsum_adjust(ptr + hdrlen, NAPI_GRO_CB(skb)->csum,
start, offset);

/* Adjust skb->csum since we changed the packet */
NAPI_GRO_CB(skb)->csum = csum_add(NAPI_GRO_CB(skb)->csum, delta);

grc->offset = (ptr + offset) - (void *)skb->head;
grc->offset = off + hdrlen + offset;
grc->delta = delta;

return ptr;
}

static inline void skb_gro_remcsum_cleanup(struct sk_buff *skb,
struct gro_remcsum *grc)
{
void *ptr;
size_t plen = grc->offset + sizeof(u16);

if (!grc->delta)
return;

remcsum_unadjust((__sum16 *)(skb->head + grc->offset), grc->delta);
ptr = skb_gro_header_fast(skb, grc->offset);
if (skb_gro_header_hard(skb, grc->offset + sizeof(u16))) {
ptr = skb_gro_header_slow(skb, plen, grc->offset);
if (!ptr)
return;
}

remcsum_unadjust((__sum16 *)ptr, grc->delta);
}

static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev,
Expand Down
28 changes: 12 additions & 16 deletions net/ipv4/fou.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -79,7 +79,11 @@ static struct guehdr *gue_remcsum(struct sk_buff *skb, struct guehdr *guehdr,
__be16 *pd = data;
size_t start = ntohs(pd[0]);
size_t offset = ntohs(pd[1]);
size_t plen = hdrlen + max_t(size_t, offset + sizeof(u16), start);
size_t plen = sizeof(struct udphdr) + hdrlen +
max_t(size_t, offset + sizeof(u16), start);

if (skb->remcsum_offload)
return guehdr;

if (!pskb_may_pull(skb, plen))
return NULL;
Expand Down Expand Up @@ -221,29 +225,21 @@ static int fou_gro_complete(struct sk_buff *skb, int nhoff,

static struct guehdr *gue_gro_remcsum(struct sk_buff *skb, unsigned int off,
struct guehdr *guehdr, void *data,
size_t hdrlen, u8 ipproto,
struct gro_remcsum *grc, bool nopartial)
size_t hdrlen, struct gro_remcsum *grc,
bool nopartial)
{
__be16 *pd = data;
size_t start = ntohs(pd[0]);
size_t offset = ntohs(pd[1]);
size_t plen = hdrlen + max_t(size_t, offset + sizeof(u16), start);

if (skb->remcsum_offload)
return NULL;
return guehdr;

if (!NAPI_GRO_CB(skb)->csum_valid)
return NULL;

/* Pull checksum that will be written */
if (skb_gro_header_hard(skb, off + plen)) {
guehdr = skb_gro_header_slow(skb, off + plen, off);
if (!guehdr)
return NULL;
}

skb_gro_remcsum_process(skb, (void *)guehdr + hdrlen,
start, offset, grc, nopartial);
guehdr = skb_gro_remcsum_process(skb, (void *)guehdr, off, hdrlen,
start, offset, grc, nopartial);

skb->remcsum_offload = 1;

Expand Down Expand Up @@ -307,10 +303,10 @@ static struct sk_buff **gue_gro_receive(struct sk_buff **head,

if (flags & GUE_PFLAG_REMCSUM) {
guehdr = gue_gro_remcsum(skb, off, guehdr,
data + doffset, hdrlen,
guehdr->proto_ctype, &grc,
data + doffset, hdrlen, &grc,
!!(fou->flags &
FOU_F_REMCSUM_NOPARTIAL));

if (!guehdr)
goto out;

Expand Down

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