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ppp: remove pch->chan NULL checks from tx path

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Now that ppp_disconnect_channel() is called before pch->chan is set to
NULL, a channel from ppp->channels list on the transmit path is
guaranteed to have non-NULL pch->chan.

Remove the pch->chan NULL checks from ppp_push(), ppp_mp_explode(), and
ppp_fill_forward_path(), where a channel is obtained from the list.
Remove the corresponding WRITE/READ_ONCE annotations as they no longer
race.

Signed-off-by: Qingfang Deng <dqfext@gmail.com>
Link: https://patch.msgid.link/20260312093732.277254-2-dqfext@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Qingfang Deng 2026-03-12 17:37:31 +08:00 committed by Paolo Abeni
parent 6a196e83a1
commit febe801245
1 changed files with 20 additions and 46 deletions
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66
drivers/net/ppp/ppp_generic.c
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@ -1602,10 +1602,7 @@ static int ppp_fill_forward_path(struct net_device_path_ctx *ctx,
if (!pch)
return -ENODEV;
chan = READ_ONCE(pch->chan);
if (!chan)
return -ENODEV;
chan = pch->chan;
if (!chan->ops->fill_forward_path)
return -EOPNOTSUPP;
@ -1928,9 +1925,9 @@ ppp_push(struct ppp *ppp, struct sk_buff *skb)
spin_lock(&pch->downl);
chan = pch->chan;
if (unlikely(!chan || (!chan->direct_xmit && skb_linearize(skb)))) {
/* channel got unregistered, or it requires a linear
* skb but linearization failed
if (unlikely(!chan->direct_xmit && skb_linearize(skb))) {
/* channel requires a linear skb but linearization
* failed
*/
kfree_skb(skb);
ret = 1;
@ -1991,28 +1988,23 @@ static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
i = 0;
list_for_each_entry(pch, &ppp->channels, clist) {
if (pch->chan) {
pch->avail = 1;
navail++;
pch->speed = pch->chan->speed;
} else {
pch->avail = 0;
}
if (pch->avail) {
if (skb_queue_empty(&pch->file.xq) ||
!pch->had_frag) {
if (pch->speed == 0)
nzero++;
else
totspeed += pch->speed;
pch->avail = 1;
navail++;
pch->speed = pch->chan->speed;
pch->avail = 2;
++nfree;
++totfree;
}
if (!pch->had_frag && i < ppp->nxchan)
ppp->nxchan = i;
if (skb_queue_empty(&pch->file.xq) || !pch->had_frag) {
if (pch->speed == 0)
nzero++;
else
totspeed += pch->speed;
pch->avail = 2;
++nfree;
++totfree;
}
if (!pch->had_frag && i < ppp->nxchan)
ppp->nxchan = i;
++i;
}
/*
@ -2071,25 +2063,7 @@ static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
pch->avail = 1;
}
/* check the channel's mtu and whether it is still attached. */
spin_lock(&pch->downl);
if (pch->chan == NULL) {
/* can't use this channel, it's being deregistered */
if (pch->speed == 0)
nzero--;
else
totspeed -= pch->speed;
spin_unlock(&pch->downl);
pch->avail = 0;
totlen = len;
totfree--;
nfree--;
if (--navail == 0)
break;
continue;
}
/*
*if the channel speed is not set divide
*the packet evenly among the free channels;
@ -3035,7 +3009,7 @@ ppp_unregister_channel(struct ppp_channel *chan)
ppp_disconnect_channel(pch);
down_write(&pch->chan_sem);
spin_lock_bh(&pch->downl);
WRITE_ONCE(pch->chan, NULL);
pch->chan = NULL;
spin_unlock_bh(&pch->downl);
up_write(&pch->chan_sem);