ppp: use IFF_NO_QUEUE in virtual interfaces

For PPPoE, PPTP, and PPPoL2TP, the start_xmit() function directly
forwards packets to the underlying network stack and never returns
anything other than 1. So these interfaces do not require a qdisc,
and the IFF_NO_QUEUE flag should be set.

Introduces a direct_xmit flag in struct ppp_channel to indicate when
IFF_NO_QUEUE should be applied. The flag is set in ppp_connect_channel()
for relevant protocols.

While at it, remove the usused latency member from struct ppp_channel.

Signed-off-by: Qingfang Deng <dqfext@gmail.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://patch.msgid.link/20250301135517.695809-1-dqfext@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 6220866258fc43c1e2914a637ba8618d540afd67..815108c98b78c6aa824c7e0bd57a6f6fadf0713a 100644 (file)
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -3493,6 +3493,10 @@ ppp_connect_channel(struct channel *pch, int unit)
                ret = -ENOTCONN;
                goto outl;
        }
+       if (pch->chan->direct_xmit)
+               ppp->dev->priv_flags |= IFF_NO_QUEUE;
+       else
+               ppp->dev->priv_flags &= ~IFF_NO_QUEUE;
        spin_unlock_bh(&pch->downl);
        if (pch->file.hdrlen > ppp->file.hdrlen)
                ppp->file.hdrlen = pch->file.hdrlen;

diff --git a/drivers/net/ppp/pppoe.c b/drivers/net/ppp/pppoe.c
index 2ea4f4890d23b5f1c5229c7f8b303ee85a954037..68e631718ab0b675c6ba98dcac4f8468f3d2e21e 100644 (file)
--- a/drivers/net/ppp/pppoe.c
+++ b/drivers/net/ppp/pppoe.c
@@ -693,6 +693,7 @@ static int pppoe_connect(struct socket *sock, struct sockaddr *uservaddr,
                po->chan.mtu = dev->mtu - sizeof(struct pppoe_hdr) - 2;
                po->chan.private = sk;
                po->chan.ops = &pppoe_chan_ops;
+               po->chan.direct_xmit = true;
 
                error = ppp_register_net_channel(dev_net(dev), &po->chan);
                if (error) {

diff --git a/drivers/net/ppp/pptp.c b/drivers/net/ppp/pptp.c
index 689687bd2574bcd41e857584a4b692c42d2ccba7..5feaa70b5f47e6cd33fbaff33f6715f42c4d71b5 100644 (file)
--- a/drivers/net/ppp/pptp.c
+++ b/drivers/net/ppp/pptp.c
@@ -465,6 +465,7 @@ static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
        po->chan.mtu -= PPTP_HEADER_OVERHEAD;
 
        po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);
+       po->chan.direct_xmit = true;
        error = ppp_register_channel(&po->chan);
        if (error) {
                pr_err("PPTP: failed to register PPP channel (%d)\n", error);

diff --git a/include/linux/ppp_channel.h b/include/linux/ppp_channel.h
index 45e6e427ceb8a08566b0fcc1a41b0aa6a91172e0..f73fbea0dbc239a22b59bc273afbd405cb4c2037 100644 (file)
--- a/include/linux/ppp_channel.h
+++ b/include/linux/ppp_channel.h
@@ -42,8 +42,7 @@ struct ppp_channel {
        int             hdrlen;         /* amount of headroom channel needs */
        void            *ppp;           /* opaque to channel */
        int             speed;          /* transfer rate (bytes/second) */
-       /* the following is not used at present */
-       int             latency;        /* overhead time in milliseconds */
+       bool            direct_xmit;    /* no qdisc, xmit directly */
 };
 
 #ifdef __KERNEL__

diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 53baf2dd5d5dab2ce37ee8947742c94c2b37127e..fc5c2fd8f34c7ec23e6f5ab978ea96c9f48ac81d 100644 (file)
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -806,6 +806,7 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
        po->chan.private = sk;
        po->chan.ops     = &pppol2tp_chan_ops;
        po->chan.mtu     = pppol2tp_tunnel_mtu(tunnel);
+       po->chan.direct_xmit    = true;
 
        error = ppp_register_net_channel(sock_net(sk), &po->chan);
        if (error) {