Hi Alex On 05/10/14 18:50, Alexander Aring wrote:
Wasn't it separated in v1 patch series and you asked me to combine into one patch??Hi Martin, On Wed, Oct 01, 2014 at 01:10:22PM +0100, Martin Townsend wrote:Currently there are a number of error paths in the lowpan_rcv function that free the skb before returning, the patch simplifies the receive path by ensuring that the skb is only freed from this function. Passing the skb from 6lowpan up to the higher layers is not a function of IPHC. By moving it out of IPHC we also remove the need to support error code returns with NET_RX codes.I think we should split the movement of "passing skb to higher layer" into a separate patch.
If you are decompressing UDP header then you also have to decompress the IP Header below it. This would mean that 2 pskb_expand_head calls would be needed which could result in 2 data copies which seems a waste, why not just do it once?It also makes the lowpan_rcv function more extendable as we can support more compression schemes. With the above 2 lowpan_rcv is refactored so eliminate incorrect return values. Signed-off-by: Martin Townsend <martin.townsend@xxxxxxxxxx> --- include/net/6lowpan.h | 9 +++-- net/6lowpan/iphc.c | 92 ++++++++++++++++--------------------------- net/bluetooth/6lowpan.c | 52 ++++++++++++++++-------- net/ieee802154/6lowpan_rtnl.c | 66 ++++++++++++++++++++----------- 4 files changed, 117 insertions(+), 102 deletions(-) diff --git a/include/net/6lowpan.h b/include/net/6lowpan.h index d184df1..05ff67e 100644 --- a/include/net/6lowpan.h +++ b/include/net/6lowpan.h @@ -374,10 +374,11 @@ lowpan_uncompress_size(const struct sk_buff *skb, u16 *dgram_offset)typedef int (*skb_delivery_cb)(struct sk_buff *skb, struct net_device *dev); -int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,- const u8 *saddr, const u8 saddr_type, const u8 saddr_len, - const u8 *daddr, const u8 daddr_type, const u8 daddr_len, - u8 iphc0, u8 iphc1, skb_delivery_cb skb_deliver); +int +lowpan_process_data(struct sk_buff *skb, struct net_device *dev, + const u8 *saddr, const u8 saddr_type, const u8 saddr_len, + const u8 *daddr, const u8 daddr_type, const u8 daddr_len, + u8 iphc0, u8 iphc1); int lowpan_header_compress(struct sk_buff *skb, struct net_device *dev, unsigned short type, const void *_daddr, const void *_saddr, unsigned int len); diff --git a/net/6lowpan/iphc.c b/net/6lowpan/iphc.c index 142eef5..3888357 100644 --- a/net/6lowpan/iphc.c +++ b/net/6lowpan/iphc.c @@ -171,37 +171,6 @@ static int uncompress_context_based_src_addr(struct sk_buff *skb, return 0; }-static int skb_deliver(struct sk_buff *skb, struct ipv6hdr *hdr,- struct net_device *dev, skb_delivery_cb deliver_skb) -{ - struct sk_buff *new; - int stat; - - new = skb_copy_expand(skb, sizeof(struct ipv6hdr), skb_tailroom(skb), - GFP_ATOMIC); - kfree_skb(skb); - - if (!new) - return -ENOMEM; - - skb_push(new, sizeof(struct ipv6hdr)); - skb_reset_network_header(new); - skb_copy_to_linear_data(new, hdr, sizeof(struct ipv6hdr)); - - new->protocol = htons(ETH_P_IPV6); - new->pkt_type = PACKET_HOST; - new->dev = dev; - - raw_dump_table(__func__, "raw skb data dump before receiving", - new->data, new->len); - - stat = deliver_skb(new, dev); - - kfree_skb(new); - - return stat; -} - /* Uncompress function for multicast destination address, * when M bit is set. */ @@ -332,10 +301,11 @@ err: /* TTL uncompression values */ static const u8 lowpan_ttl_values[] = { 0, 1, 64, 255 };-int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,- const u8 *saddr, const u8 saddr_type, const u8 saddr_len, - const u8 *daddr, const u8 daddr_type, const u8 daddr_len, - u8 iphc0, u8 iphc1, skb_delivery_cb deliver_skb) +int +lowpan_process_data(struct sk_buff *skb, struct net_device *dev, + const u8 *saddr, const u8 saddr_type, const u8 saddr_len, + const u8 *daddr, const u8 daddr_type, const u8 daddr_len, + u8 iphc0, u8 iphc1) { struct ipv6hdr hdr = {}; u8 tmp, num_context = 0; @@ -348,7 +318,7 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev, if (iphc1 & LOWPAN_IPHC_CID) { pr_debug("CID flag is set, increase header with one\n"); if (lowpan_fetch_skb(skb, &num_context, sizeof(num_context))) - goto drop; + return -EINVAL; }hdr.version = 6;@@ -360,7 +330,7 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev, */ case 0: /* 00b */ if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp))) - goto drop; + return -EINVAL;memcpy(&hdr.flow_lbl, &skb->data[0], 3);skb_pull(skb, 3); @@ -373,7 +343,7 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev, */ case 2: /* 10b */ if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp))) - goto drop; + return -EINVAL;hdr.priority = ((tmp >> 2) & 0x0f);hdr.flow_lbl[0] = ((tmp << 6) & 0xC0) | ((tmp >> 2) & 0x30); @@ -383,7 +353,7 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev, */ case 1: /* 01b */ if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp))) - goto drop; + return -EINVAL;hdr.flow_lbl[0] = (skb->data[0] & 0x0F) | ((tmp >> 2) & 0x30);memcpy(&hdr.flow_lbl[1], &skb->data[0], 2); @@ -400,7 +370,7 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev, if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) { /* Next header is carried inline */ if (lowpan_fetch_skb(skb, &hdr.nexthdr, sizeof(hdr.nexthdr))) - goto drop; + return -EINVAL;pr_debug("NH flag is set, next header carried inline: %02x\n",hdr.nexthdr); @@ -412,7 +382,7 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev, } else { if (lowpan_fetch_skb(skb, &hdr.hop_limit, sizeof(hdr.hop_limit))) - goto drop; + return -EINVAL; }/* Extract SAM to the tmp variable */@@ -431,7 +401,7 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,/* Check on error of previous branch */if (err) - goto drop; + return -EINVAL;/* Extract DAM to the tmp variable */tmp = ((iphc1 & LOWPAN_IPHC_DAM_11) >> LOWPAN_IPHC_DAM_BIT) & 0x03; @@ -446,7 +416,7 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev, tmp);if (err)- goto drop; + return -EINVAL; } } else { err = uncompress_addr(skb, &hdr.daddr, tmp, daddr, @@ -454,28 +424,26 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev, pr_debug("dest: stateless compression mode %d dest %pI6c\n", tmp, &hdr.daddr); if (err) - goto drop; + return -EINVAL; }/* UDP data uncompression */if (iphc0 & LOWPAN_IPHC_NH_C) { struct udphdr uh; - struct sk_buff *new;if (uncompress_udp_header(skb, &uh))- goto drop; + return -EINVAL;/* replace the compressed UDP head by the uncompressed UDP* header */ - new = skb_copy_expand(skb, sizeof(struct udphdr), - skb_tailroom(skb), GFP_ATOMIC); - kfree_skb(skb); - - if (!new) - return -ENOMEM; + if (skb_headroom(skb) < sizeof(struct udphdr) + sizeof(hdr)) { + int n = sizeof(struct udphdr) + sizeof(hdr);For this also a separate for "check if we have enough headroom". This has nothing to do with the errno fix. All patches should follow "keep it short and simple" not doing too much in a patch, if you can separate it then separate it. Then we have a better overview while reviewing and a nice git commit history. Also this should be "if (skb_headroom(skb) < sizeof(struct udphdr))" only, without the sizeof(hdr). Why you check also for space for ipv6 header here? This is part of transport header.
- skb = new;+ err = pskb_expand_head(skb, n, 0, GFP_ATOMIC); + if (unlikely(err)) + return err; + }skb_push(skb, sizeof(struct udphdr));Here we add data for udphdr only. Then check only for headroom for udphdr.skb_reset_transport_header(skb); @@ -485,6 +453,13 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev, (u8 *)&uh, sizeof(uh));hdr.nexthdr = UIP_PROTO_UDP;+ } else {Now I see why you make "sizeof(struct udphdr) + sizeof(hdr)" Better remove this else branch and then simple make: "if (skb_headroom(skb) < sizeof(hdr))", then we don't need to check this above. This is a little bit confusing.
See above, maybe a comment would help things?
+ if (skb_headroom(skb) < sizeof(hdr)) { + err = pskb_expand_head(skb, sizeof(hdr), 0, GFP_ATOMIC); +remove this whitespace.
ok.
The intention of the code is to ensure that there is enough headroom before this push. Maybe the following pseudocode helps :)+ if (unlikely(err)) + return err; + } }hdr.payload_len = htons(skb->len);@@ -499,11 +474,14 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,raw_dump_table(__func__, "raw header dump", (u8 *)&hdr, sizeof(hdr)); - return skb_deliver(skb, &hdr, dev, deliver_skb);+ skb_push(skb, sizeof(hdr));Here is the push for sizeof(hdr) above we should _always_ check for "(skb_headroom(skb) < sizeof(hdr))".
IF UDP Hdr Compression
ensure enough room for UDP Hdr and IPv6 Hdr
make room for UDP Hdr (skb_push)
decompress UDP Hdr
ELSE
ensure enough room for IPv6 Hdr
make room for IPv6 Hdr (skb_push)
decompress IPv6 Hdr
It's necessary as pskb_expand_head must have no references as you are potentially reallocating the data part of the skb. It's position is questionable but until other compression schemes are supported it will suffice.The code is much similar for udphdr and hdr, here.... create a static function in this file, then we have a generic function for this (this is useful for other transport header when next header compression layer comes mainline. protoype looks like: int skb_check_and_expand(struct sk_buff *skb, size_t len) should contain something like: if (skb_headroom(skb) < len) do_expand_stuff(skb....); return 0;+ skb_reset_network_header(skb); + skb_copy_to_linear_data(skb, &hdr, sizeof(hdr));-drop:- kfree_skb(skb); - return -EINVAL; + raw_dump_table(__func__, "raw skb data dump before receiving", + skb->data, skb->len); + + return 0; } EXPORT_SYMBOL_GPL(lowpan_process_data);diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.cindex 206b65c..adfd361 100644 --- a/net/bluetooth/6lowpan.c +++ b/net/bluetooth/6lowpan.c @@ -230,36 +230,31 @@ static int process_data(struct sk_buff *skb, struct net_device *netdev, peer = peer_lookup_chan(dev, chan); read_unlock_irqrestore(&devices_lock, flags); if (!peer) - goto drop; + return -EINVAL;saddr = peer->eui64_addr;daddr = dev->netdev->dev_addr;/* at least two bytes will be used for the encoding */if (skb->len < 2) - goto drop; + return -EINVAL;if (lowpan_fetch_skb_u8(skb, &iphc0))- goto drop; + return -EINVAL;if (lowpan_fetch_skb_u8(skb, &iphc1))- goto drop; + return -EINVAL;return lowpan_process_data(skb, netdev,saddr, IEEE802154_ADDR_LONG, EUI64_ADDR_LEN, daddr, IEEE802154_ADDR_LONG, EUI64_ADDR_LEN, - iphc0, iphc1, give_skb_to_upper); - -drop: - kfree_skb(skb); - return -EINVAL; + iphc0, iphc1); }static int recv_pkt(struct sk_buff *skb, struct net_device *dev,struct l2cap_chan *chan) { struct sk_buff *local_skb; - int ret;if (!netif_running(dev))goto drop; @@ -280,12 +275,8 @@ static int recv_pkt(struct sk_buff *skb, struct net_device *dev, local_skb->protocol = htons(ETH_P_IPV6); local_skb->pkt_type = PACKET_HOST;- skb_reset_network_header(local_skb);- skb_set_transport_header(local_skb, sizeof(struct ipv6hdr)); - if (give_skb_to_upper(local_skb, dev) != NET_RX_SUCCESS) { - kfree_skb(local_skb); - goto drop; + goto drop_local_skb; }dev->stats.rx_bytes += skb->len;@@ -294,15 +285,40 @@ static int recv_pkt(struct sk_buff *skb, struct net_device *dev, kfree_skb(local_skb); kfree_skb(skb); } else { + int ret; + + if (skb_cloned(skb)) {why is this now here? Is this necessary, we don't have such thing current mainline, if necessary make a separate patch for this or put it in the right one.
sorry, I didn't intend to writing confusing code, wait until you see the GHC patch :)+ struct sk_buff *new; + int new_headroom = sizeof(struct ipv6hdr) + + sizeof(struct udphdr); + + new = skb_copy_expand(skb, new_headroom, + skb_tailroom(skb), GFP_ATOMIC); + if (!new) + return -ENOMEM; + consume_skb(skb); + skb = new; + } + switch (skb->data[0] & 0xe0) { case LOWPAN_DISPATCH_IPHC: /* ipv6 datagram */ + + ret = process_data(skb, dev, chan); + if (ret < 0) + goto drop; + local_skb = skb_clone(skb, GFP_ATOMIC); if (!local_skb) goto drop;This looks a little bit confusing, I will look at this when you sperate the patches. Again "move handling to upper layer" and the "check if expand is necessary". Then I will look at this code for correct "kfree_skb" and "consume_skb" calling. Hope this is okay, I need to decrypt this code at first. :-)
If I'm going to base it on bluetooth-next then I think the best solution is to submit separate patches in stagesSorry too much changes in one patch, we need to split this one. Also base it on bluetooth-next, should be complicated to megre this stuff for bluetooth with -next... - Alex
1) Checking for headroom and using pskb_expand_head for decompression:reason for patch: saves on copying the whole structure and there potentially might not be a copy especially if the driver allocates a larger buffer than needed knowing that it will be decompressed
2) Move delivery out of IPHC.reason: Ensures return value isn't a mish mash of error codes and NET_RX_ codes, allows for better scalability as we don't have a requirement for decompression to pass the skb onto the next layer
3) Fix lowpan_rcv reason: Fix those pesky return value problems Then I can go on to submit those 2 outstanding patches 4) Refactor lowpan_rcv to handle fragmented uncompressed IPv6 packets. 5) Rename process_data etc..I think this will help Jukka as my patch currently breaks their transmit code and we could see which part causes this. Also I'm really busy at the moment writing a QEMU virtual device to model our transceiver so we can get a virtual test bed working as well as a couple of other things so it would be better for me to concentrate on one patch at a time as time is something I don't have a lot of at the moment :)
Would you be happy with this? I know it means the bug fix happens third, but I think it will be better in the long run.
- Martin -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
