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authorNeil Horman <nhorman@tuxdriver.com>2016-05-02 12:20:15 -0400
committerSasha Levin <sasha.levin@oracle.com>2016-07-12 08:48:12 -0400
commit3f6683aa55a4be9867b4128f396aa955b19db78b (patch)
tree602bb9a3d7f35b261b2ba78bc81a841e1c0f7574
parent13baacbfc6feca83054aaff5ecae28a32cb11ea1 (diff)
downloadlinux-linaro-stable-3f6683aa55a4be9867b4128f396aa955b19db78b.tar.gz
netem: Segment GSO packets on enqueue
[ Upstream commit 6071bd1aa13ed9e41824bafad845b7b7f4df5cfd ] This was recently reported to me, and reproduced on the latest net kernel, when attempting to run netperf from a host that had a netem qdisc attached to the egress interface: [ 788.073771] ---------------------[ cut here ]--------------------------- [ 788.096716] WARNING: at net/core/dev.c:2253 skb_warn_bad_offload+0xcd/0xda() [ 788.129521] bnx2: caps=(0x00000001801949b3, 0x0000000000000000) len=2962 data_len=0 gso_size=1448 gso_type=1 ip_summed=3 [ 788.182150] Modules linked in: sch_netem kvm_amd kvm crc32_pclmul ipmi_ssif ghash_clmulni_intel sp5100_tco amd64_edac_mod aesni_intel lrw gf128mul glue_helper ablk_helper edac_mce_amd cryptd pcspkr sg edac_core hpilo ipmi_si i2c_piix4 k10temp fam15h_power hpwdt ipmi_msghandler shpchp acpi_power_meter pcc_cpufreq nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c sd_mod crc_t10dif crct10dif_generic mgag200 syscopyarea sysfillrect sysimgblt i2c_algo_bit drm_kms_helper ahci ata_generic pata_acpi ttm libahci crct10dif_pclmul pata_atiixp tg3 libata crct10dif_common drm crc32c_intel ptp serio_raw bnx2 r8169 hpsa pps_core i2c_core mii dm_mirror dm_region_hash dm_log dm_mod [ 788.465294] CPU: 16 PID: 0 Comm: swapper/16 Tainted: G W ------------ 3.10.0-327.el7.x86_64 #1 [ 788.511521] Hardware name: HP ProLiant DL385p Gen8, BIOS A28 12/17/2012 [ 788.542260] ffff880437c036b8 f7afc56532a53db9 ffff880437c03670 ffffffff816351f1 [ 788.576332] ffff880437c036a8 ffffffff8107b200 ffff880633e74200 ffff880231674000 [ 788.611943] 0000000000000001 0000000000000003 0000000000000000 ffff880437c03710 [ 788.647241] Call Trace: [ 788.658817] <IRQ> [<ffffffff816351f1>] dump_stack+0x19/0x1b [ 788.686193] [<ffffffff8107b200>] warn_slowpath_common+0x70/0xb0 [ 788.713803] [<ffffffff8107b29c>] warn_slowpath_fmt+0x5c/0x80 [ 788.741314] [<ffffffff812f92f3>] ? ___ratelimit+0x93/0x100 [ 788.767018] [<ffffffff81637f49>] skb_warn_bad_offload+0xcd/0xda [ 788.796117] [<ffffffff8152950c>] skb_checksum_help+0x17c/0x190 [ 788.823392] [<ffffffffa01463a1>] netem_enqueue+0x741/0x7c0 [sch_netem] [ 788.854487] [<ffffffff8152cb58>] dev_queue_xmit+0x2a8/0x570 [ 788.880870] [<ffffffff8156ae1d>] ip_finish_output+0x53d/0x7d0 ... The problem occurs because netem is not prepared to handle GSO packets (as it uses skb_checksum_help in its enqueue path, which cannot manipulate these frames). The solution I think is to simply segment the skb in a simmilar fashion to the way we do in __dev_queue_xmit (via validate_xmit_skb), with some minor changes. When we decide to corrupt an skb, if the frame is GSO, we segment it, corrupt the first segment, and enqueue the remaining ones. tested successfully by myself on the latest net kernel, to which this applies Signed-off-by: Neil Horman <nhorman@tuxdriver.com> CC: Jamal Hadi Salim <jhs@mojatatu.com> CC: "David S. Miller" <davem@davemloft.net> CC: netem@lists.linux-foundation.org CC: eric.dumazet@gmail.com CC: stephen@networkplumber.org Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
-rw-r--r--net/sched/sch_netem.c61
1 files changed, 59 insertions, 2 deletions
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index fac07d534fb7..f60db2b3e5ef 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -408,6 +408,25 @@ static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
sch->q.qlen++;
}
+/* netem can't properly corrupt a megapacket (like we get from GSO), so instead
+ * when we statistically choose to corrupt one, we instead segment it, returning
+ * the first packet to be corrupted, and re-enqueue the remaining frames
+ */
+static struct sk_buff *netem_segment(struct sk_buff *skb, struct Qdisc *sch)
+{
+ struct sk_buff *segs;
+ netdev_features_t features = netif_skb_features(skb);
+
+ segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
+
+ if (IS_ERR_OR_NULL(segs)) {
+ qdisc_reshape_fail(skb, sch);
+ return NULL;
+ }
+ consume_skb(skb);
+ return segs;
+}
+
/*
* Insert one skb into qdisc.
* Note: parent depends on return value to account for queue length.
@@ -420,7 +439,11 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
/* We don't fill cb now as skb_unshare() may invalidate it */
struct netem_skb_cb *cb;
struct sk_buff *skb2;
+ struct sk_buff *segs = NULL;
+ unsigned int len = 0, last_len, prev_len = qdisc_pkt_len(skb);
+ int nb = 0;
int count = 1;
+ int rc = NET_XMIT_SUCCESS;
/* Random duplication */
if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
@@ -466,10 +489,23 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
* do it now in software before we mangle it.
*/
if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
+ if (skb_is_gso(skb)) {
+ segs = netem_segment(skb, sch);
+ if (!segs)
+ return NET_XMIT_DROP;
+ } else {
+ segs = skb;
+ }
+
+ skb = segs;
+ segs = segs->next;
+
if (!(skb = skb_unshare(skb, GFP_ATOMIC)) ||
(skb->ip_summed == CHECKSUM_PARTIAL &&
- skb_checksum_help(skb)))
- return qdisc_drop(skb, sch);
+ skb_checksum_help(skb))) {
+ rc = qdisc_drop(skb, sch);
+ goto finish_segs;
+ }
skb->data[prandom_u32() % skb_headlen(skb)] ^=
1<<(prandom_u32() % 8);
@@ -529,6 +565,27 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
sch->qstats.requeues++;
}
+finish_segs:
+ if (segs) {
+ while (segs) {
+ skb2 = segs->next;
+ segs->next = NULL;
+ qdisc_skb_cb(segs)->pkt_len = segs->len;
+ last_len = segs->len;
+ rc = qdisc_enqueue(segs, sch);
+ if (rc != NET_XMIT_SUCCESS) {
+ if (net_xmit_drop_count(rc))
+ qdisc_qstats_drop(sch);
+ } else {
+ nb++;
+ len += last_len;
+ }
+ segs = skb2;
+ }
+ sch->q.qlen += nb;
+ if (nb > 1)
+ qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len);
+ }
return NET_XMIT_SUCCESS;
}