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net/packet: ignore timestamp bits when testing tx frame status

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Since the commit in Fixes, the tx completion handler writes the frame
status as TP_STATUS_AVAILABLE | ts, where ts can be
TP_STATUS_TS_SOFTWARE or TP_STATUS_TS_RAW_HARDWARE.

Two places compare a tx frame status to TP_STATUS_AVAILABLE for
equality, and so fail to detect such a released frame:

- tpacket_snd(), when packet_xmit() fails: the packet is silently
  dropped instead of an error being returned to the caller for retry.

- packet_poll(), on the tx ring head frame: the socket is not reported
  as writable.

Mask out the timestamp bits in both. In packet_lookup_frame(), only do
so when testing a tx ring frame for TP_STATUS_AVAILABLE.

Cc: stable+noautosel@kernel.org # LLM report + LLM fix, not seen in real life
Fixes: b9c32fb271 ("packet: if hw/sw ts enabled in rx/tx ring, report which ts we got")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20261004171847.186954-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Willem de Bruijn 2026-10-04 13:10:53 -04:00 committed by Jakub Kicinski
parent a9c455cd3d
commit 88fb9fad5c
1 changed files with 10 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
net/packet/af_packet.c
View File

@ -398,6 +398,10 @@ static inline struct page * __pure pgv_to_page(void *addr)
return virt_to_page(addr);
}
/* Timestamp bits that may be set in addition to the frame state */
static const u32 tp_status_ts_mask = TP_STATUS_TS_SOFTWARE |
TP_STATUS_TS_RAW_HARDWARE;
static void __packet_set_status(struct packet_sock *po, void *frame, int status)
{
union tpacket_uhdr h;
@ -519,6 +523,7 @@ static void *packet_lookup_frame(const struct packet_sock *po,
{
unsigned int pg_vec_pos, frame_offset;
union tpacket_uhdr h;
u32 mask = 0;
pg_vec_pos = position / rb->frames_per_block;
frame_offset = position % rb->frames_per_block;
@ -526,7 +531,10 @@ static void *packet_lookup_frame(const struct packet_sock *po,
h.raw = rb->pg_vec[pg_vec_pos].buffer +
(frame_offset * rb->frame_size);
if (status != __packet_get_status(po, h.raw))
if (rb == &po->tx_ring && status == TP_STATUS_AVAILABLE)
mask = tp_status_ts_mask;
if (status != (__packet_get_status(po, h.raw) & ~mask))
return NULL;
return h.raw;
@ -2947,7 +2955,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
if (unlikely(err != 0)) {
if (err > 0)
err = net_xmit_errno(err);
if (err && __packet_get_status(po, ph) ==
if (err && (__packet_get_status(po, ph) & ~tp_status_ts_mask) ==
TP_STATUS_AVAILABLE) {
/* skb was destructed already */
skb = NULL;