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net: net_test: add tests for TCP re-segmentation

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The GSO engine can now be asked to group several MSS segments into one
output skb, which is what re-segmentation needs.  Add KUnit coverage for
the max_segs parameter.

The parameterized GSO test gains a max_segs input and four cases: a limit
of two MSS applied to a 3003 byte and to a 5003 byte payload, a tail which
holds one MSS and is therefore not a GSO skb, and a max_segs of one MSS
which must leave the output unchanged.  It drives skb_segment() directly,
because the synthetic protocol it uses has no gso_segment callback.

Assisted-by: LLM
Signed-off-by: Wang Zhan <wang.zhan@smartx.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20261008100651.2534957-7-wang.zhan@smartx.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Wang Zhan 2026-10-08 18:06:51 +08:00 committed by Paolo Abeni
parent 32bfd220cd
commit a374c5bb41
1 changed files with 87 additions and 0 deletions
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87
net/core/net_test.c
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@ -5,6 +5,7 @@
/* GSO */
#include <linux/skbuff.h>
#include <net/gso.h>
static const char hdr[] = "abcdefgh";
#define GSO_TEST_SIZE 1000
@ -34,6 +35,10 @@ enum gso_test_nr {
GSO_TEST_FRAG_LIST_PURE,
GSO_TEST_FRAG_LIST_NON_UNIFORM,
GSO_TEST_GSO_BY_FRAGS,
GSO_TEST_RESEGMENT,
GSO_TEST_RESEGMENT_MULTI,
GSO_TEST_RESEGMENT_TAIL,
GSO_TEST_RESEGMENT_ONE_MSS,
};
struct gso_test_case {
@ -46,10 +51,12 @@ struct gso_test_case {
const unsigned int *frags;
unsigned int nr_frag_skbs;
const unsigned int *frag_skbs;
unsigned int max_segs;
/* output as expected */
unsigned int nr_segs;
const unsigned int *segs;
const unsigned int *gso_segs;
};
static struct gso_test_case cases[] = {
@ -135,6 +142,68 @@ static struct gso_test_case cases[] = {
.nr_segs = 4,
.segs = (const unsigned int[]) { 100, 200, 300, 400 },
},
{
.id = GSO_TEST_RESEGMENT,
.name = "resegment",
.linear_len = GSO_TEST_SIZE,
.nr_frags = 3,
.frags = (const unsigned int[]) {
GSO_TEST_SIZE, GSO_TEST_SIZE, 3,
},
.max_segs = 2,
.nr_segs = 2,
.segs = (const unsigned int[]) {
2 * GSO_TEST_SIZE, GSO_TEST_SIZE + 3,
},
.gso_segs = (const unsigned int[]) { 2, 2 },
},
{
.id = GSO_TEST_RESEGMENT_MULTI,
.name = "resegment_multi",
.linear_len = 2 * GSO_TEST_SIZE,
.nr_frags = 4,
.frags = (const unsigned int[]) {
GSO_TEST_SIZE, GSO_TEST_SIZE, GSO_TEST_SIZE, 3,
},
.max_segs = 2,
.nr_segs = 3,
.segs = (const unsigned int[]) {
2 * GSO_TEST_SIZE, 2 * GSO_TEST_SIZE, GSO_TEST_SIZE + 3,
},
.gso_segs = (const unsigned int[]) { 2, 2, 2 },
},
{
/* The last output is not a GSO skb. */
.id = GSO_TEST_RESEGMENT_TAIL,
.name = "resegment_tail",
.linear_len = GSO_TEST_SIZE,
.nr_frags = 2,
.frags = (const unsigned int[]) {
GSO_TEST_SIZE, 400,
},
.max_segs = 2,
.nr_segs = 2,
.segs = (const unsigned int[]) {
2 * GSO_TEST_SIZE, 400,
},
.gso_segs = (const unsigned int[]) { 2, 0 },
},
{
/* max_segs of 1 is the same as no limit. */
.id = GSO_TEST_RESEGMENT_ONE_MSS,
.name = "resegment_one_mss",
.linear_len = GSO_TEST_SIZE,
.nr_frags = 3,
.frags = (const unsigned int[]) {
GSO_TEST_SIZE, GSO_TEST_SIZE, 3,
},
.max_segs = 1,
.nr_segs = 4,
.segs = (const unsigned int[]) {
GSO_TEST_SIZE, GSO_TEST_SIZE, GSO_TEST_SIZE, 3,
},
.gso_segs = (const unsigned int[]) { 0, 0, 0, 0 },
},
};
static void gso_test_case_to_desc(struct gso_test_case *t, char *desc)
@ -226,6 +295,7 @@ static void gso_test_func(struct kunit *test)
if (tcase->id == GSO_TEST_FRAG_LIST_NON_UNIFORM)
features &= ~NETIF_F_SG;
SKB_GSO_CB(skb)->max_segs = tcase->max_segs;
segs = skb_segment(skb, features);
if (IS_ERR(segs)) {
KUNIT_FAIL(test, "segs error %pe", segs);
@ -239,6 +309,9 @@ static void gso_test_func(struct kunit *test)
for (cur = segs, i = 0; cur; cur = next, i++) {
next = cur->next;
if (i >= tcase->nr_segs)
goto consume;
KUNIT_ASSERT_EQ(test, cur->len, sizeof(hdr) + tcase->segs[i]);
/* segs have skb->data pointing to the mac header */
@ -247,11 +320,25 @@ static void gso_test_func(struct kunit *test)
/* header was copied to all segs */
KUNIT_ASSERT_EQ(test, memcmp(skb_mac_header(cur), hdr, sizeof(hdr)), 0);
if (tcase->gso_segs) {
unsigned int gso_segs = tcase->gso_segs[i];
KUNIT_EXPECT_EQ(test, skb_shinfo(cur)->gso_segs,
gso_segs);
if (!gso_segs) {
KUNIT_EXPECT_FALSE(test, skb_is_gso(cur));
} else {
KUNIT_EXPECT_TRUE(test, skb_is_gso(cur));
KUNIT_EXPECT_EQ(test, skb_shinfo(cur)->gso_size,
GSO_TEST_SIZE);
}
}
/* last seg can be found through segs->prev pointer */
if (!next)
KUNIT_ASSERT_PTR_EQ(test, cur, last);
consume:
consume_skb(cur);
}