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network/setlink: adjust requested MTU when it is ready to set

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This should not change any effective behavior.
Just for safety, and making the logic consistent with others, e.g.
setting master ifindex.
This commit is contained in:
Yu Watanabe
2024-04-10 12:15:33 +09:00
parent 11a150bc43
commit d4386dd1c8
1 changed files with 50 additions and 41 deletions
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src/network/networkd-setlink.c
+50 -41
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@@ -453,6 +453,43 @@ static bool netdev_is_ready(NetDev *netdev) {
return true;
}
static uint32_t link_adjust_mtu(Link *link, uint32_t mtu) {
const char *origin;
uint32_t min_mtu;
assert(link);
assert(link->network);
min_mtu = link->min_mtu;
origin = "the minimum MTU of the interface";
if (link_ipv6_enabled(link)) {
/* IPv6 protocol requires a minimum MTU of IPV6_MTU_MIN(1280) bytes on the interface. Bump up
* MTU bytes to IPV6_MTU_MIN. */
if (min_mtu < IPV6_MIN_MTU) {
min_mtu = IPV6_MIN_MTU;
origin = "the minimum IPv6 MTU";
}
if (min_mtu < link->network->ipv6_mtu) {
min_mtu = link->network->ipv6_mtu;
origin = "the requested IPv6 MTU in IPv6MTUBytes=";
}
}
if (mtu < min_mtu) {
log_link_warning(link, "Bumping the requested MTU %"PRIu32" to %s (%"PRIu32")",
mtu, origin, min_mtu);
mtu = min_mtu;
}
if (mtu > link->max_mtu) {
log_link_warning(link, "Reducing the requested MTU %"PRIu32" to the interface's maximum MTU %"PRIu32".",
mtu, link->max_mtu);
mtu = link->max_mtu;
}
return mtu;
}
static int link_is_ready_to_set_link(Link *link, Request *req) {
int r;
@@ -570,13 +607,24 @@ static int link_is_ready_to_set_link(Link *link, Request *req) {
}))
return false;
/* Changing FD mode may affect MTU. */
/* Changing FD mode may affect MTU.
* See https://docs.kernel.org/networking/can.html#can-fd-flexible-data-rate-driver-support
* MTU = 16 (CAN_MTU) => Classical CAN device
* MTU = 72 (CANFD_MTU) => CAN FD capable device */
if (ordered_set_contains(link->manager->request_queue,
&(const Request) {
.link = link,
.type = REQUEST_TYPE_SET_LINK_CAN,
}))
return false;
/* Now, it is ready to set MTU, but before setting, adjust requested MTU. */
uint32_t mtu = link_adjust_mtu(link, PTR_TO_UINT32(req->userdata));
if (mtu == link->mtu)
return -EALREADY; /* Not necessary to set the same value. */
req->userdata = UINT32_TO_PTR(mtu);
return true;
}
default:
break;
@@ -865,51 +913,12 @@ int link_request_to_set_master(Link *link) {
}
int link_request_to_set_mtu(Link *link, uint32_t mtu) {
const char *origin;
uint32_t min_mtu, max_mtu;
Request *req;
int r;
assert(link);
assert(link->network);
min_mtu = link->min_mtu;
origin = "the minimum MTU of the interface";
if (link_ipv6_enabled(link)) {
/* IPv6 protocol requires a minimum MTU of IPV6_MTU_MIN(1280) bytes on the interface. Bump up
* MTU bytes to IPV6_MTU_MIN. */
if (min_mtu < IPV6_MIN_MTU) {
min_mtu = IPV6_MIN_MTU;
origin = "the minimum IPv6 MTU";
}
if (min_mtu < link->network->ipv6_mtu) {
min_mtu = link->network->ipv6_mtu;
origin = "the requested IPv6 MTU in IPv6MTUBytes=";
}
}
if (mtu < min_mtu) {
log_link_warning(link, "Bumping the requested MTU %"PRIu32" to %s (%"PRIu32")",
mtu, origin, min_mtu);
mtu = min_mtu;
}
max_mtu = link->max_mtu;
if (link->iftype == ARPHRD_CAN)
/* The maximum MTU may be changed when FD mode is changed.
* See https://docs.kernel.org/networking/can.html#can-fd-flexible-data-rate-driver-support
* MTU = 16 (CAN_MTU) => Classical CAN device
* MTU = 72 (CANFD_MTU) => CAN FD capable device
* So, even if the current maximum is 16, we should not reduce the requested value now. */
max_mtu = MAX(max_mtu, 72u);
if (mtu > max_mtu) {
log_link_warning(link, "Reducing the requested MTU %"PRIu32" to the interface's maximum MTU %"PRIu32".",
mtu, max_mtu);
mtu = max_mtu;
}
if (link->mtu == mtu)
if (mtu == 0)
return 0;
r = link_request_set_link(link, REQUEST_TYPE_SET_LINK_MTU,