kernel/linux.git/net/core/dev.c, branch v7.0.14

net: export netif_open for self_test usage

2026-06-27T10:07:40+00:00

commit 3fdd33697c2be9184668c89ba4f24a5ecbc8ec51 upstream. dev_open() already is exported, but drivers which use the netdev instance lock need to use netif_open() instead. netif_close() is also already exported [1] so this completes the pairing. This export is required for the following fbnic self tests to avoid calling ndo_stop() and ndo_open() in favor of the more appropriate netif_open() and netif_close() that notifies any listeners that the interface went down to test and is now coming back up. Link: https://patch.msgid.link/20250309215851.2003708-1-sdf@fomichev.me [1] Signed-off-by: Mike Marciniszyn (Meta) Link: https://patch.msgid.link/20260307105847.1438-2-mike.marciniszyn@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

net: napi: Avoid gro timer misfiring at end of busypoll

2026-06-01T15:54:36+00:00

[ Upstream commit 58e2330bd45572a6e3d46ea94cf7a9641f43591a ] When in irq deferral mode (defer-hard-irqs > 0), a short enough gro-flush timeout can trigger before NAPI_STATE_SCHED is cleared if the last poll in busy_poll_stop() takes too long. This can have the effect of leaving the queue stuck with interrupts disabled and no timer armed which results in a tx timeout if there is no subsequent busypoll cycle. To prevent this, defer the gro-flush timer arm after the last poll. Fixes: 7fd3253a7de6 ("net: Introduce preferred busy-polling") Co-developed-by: Martin Karsten Signed-off-by: Martin Karsten Signed-off-by: Dragos Tatulea Reviewed-by: Tariq Toukan Reviewed-by: Cosmin Ratiu Reviewed-by: Joe Damato Link: https://patch.msgid.link/20260506090808.820559-2-dtatulea@nvidia.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: pull headers in qdisc_pkt_len_segs_init()

2026-05-23T11:08:37+00:00

[ Upstream commit 7fb4c19670110f052c04e1ec1d2b953b9f4f57e4 ] Most ndo_start_xmit() methods expects headers of gso packets to be already in skb->head. net/core/tso.c users are particularly at risk, because tso_build_hdr() does a memcpy(hdr, skb->data, hdr_len); qdisc_pkt_len_segs_init() already does a dissection of gso packets. Use pskb_may_pull() instead of skb_header_pointer() to make sure drivers do not have to reimplement this. Some malicious packets could be fed, detect them so that we can drop them sooner with a new SKB_DROP_REASON_SKB_BAD_GSO drop_reason. Fixes: e876f208af18 ("net: Add a software TSO helper API") Signed-off-by: Eric Dumazet Reviewed-by: Joe Damato Link: https://patch.msgid.link/20260403221540.3297753-3-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: qdisc_pkt_len_segs_init() cleanup

2026-05-23T11:08:37+00:00

[ Upstream commit 30e02ec3b4b6bd429a4824f125eb843a291dcccf ] Reduce indentation level by returning early if the transport header was not set. Add an unlikely() clause as this is not the common case. No functional change. Signed-off-by: Eric Dumazet Reviewed-by: Joe Damato Link: https://patch.msgid.link/20260403221540.3297753-2-edumazet@google.com Signed-off-by: Jakub Kicinski Stable-dep-of: 7fb4c1967011 ("net: pull headers in qdisc_pkt_len_segs_init()") Signed-off-by: Sasha Levin

net: plumb drop reasons to __dev_queue_xmit()

2026-05-23T11:08:37+00:00

[ Upstream commit 045f977dd4ebdd3ad8e96cf684917adfc5805adb ] Add drop reasons to __dev_queue_xmit(): - SKB_DROP_REASON_DEV_READY : device is not UP. - SKB_DROP_REASON_RECURSION_LIMIT : recursion limit on virtual device is hit. Also add an unlikely() for the SKB_DROP_REASON_DEV_READY case, and reduce indentation level. Signed-off-by: Eric Dumazet Reviewed-by: Joe Damato Link: https://patch.msgid.link/20260312201824.203093-3-edumazet@google.com Signed-off-by: Jakub Kicinski Stable-dep-of: 7fb4c1967011 ("net: pull headers in qdisc_pkt_len_segs_init()") Signed-off-by: Sasha Levin

net: use skb_header_pointer() for TCPv4 GSO frag_off check

2026-03-31T00:35:21+00:00

Syzbot reported a KMSAN uninit-value warning in gso_features_check() called from netif_skb_features() [1]. gso_features_check() reads iph->frag_off to decide whether to clear mangleid_features. Accessing the IPv4 header via ip_hdr()/inner_ip_hdr() can rely on skb header offsets that are not always safe for direct dereference on packets injected from PF_PACKET paths. Use skb_header_pointer() for the TCPv4 frag_off check so the header read is robust whether data is already linear or needs copying. [1] https://syzkaller.appspot.com/bug?extid=1543a7d954d9c6d00407 Link: https://lore.kernel.org/netdev/willemdebruijn.kernel.1a9f35039caab@gmail.com/ Fixes: cbc53e08a793 ("GSO: Add GSO type for fixed IPv4 ID") Reported-by: syzbot+1543a7d954d9c6d00407@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=1543a7d954d9c6d00407 Tested-by: syzbot+1543a7d954d9c6d00407@syzkaller.appspotmail.com Signed-off-by: Guoyu Su Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20260327153507.39742-1-yss2813483011xxl@gmail.com Signed-off-by: Jakub Kicinski

net: correctly handle tunneled traffic on IPV6_CSUM GSO fallback

2026-03-24T11:35:19+00:00

NETIF_F_IPV6_CSUM only advertises support for checksum offload of packets without IPv6 extension headers. Packets with extension headers must fall back onto software checksumming. Since TSO depends on checksum offload, those must revert to GSO. The below commit introduces that fallback. It always checks network header length. For tunneled packets, the inner header length must be checked instead. Extend the check accordingly. A special case is tunneled packets without inner IP protocol. Such as RFC 6951 SCTP in UDP. Those are not standard IPv6 followed by transport header either, so also must revert to the software GSO path. Cc: stable@vger.kernel.org Fixes: 864e3396976e ("net: gso: Forbid IPv6 TSO with extensions on devices with only IPV6_CSUM") Reported-by: Tangxin Xie Closes: https://lore.kernel.org/netdev/0414e7e2-9a1c-4d7c-a99d-b9039cf68f40@yeah.net/ Suggested-by: Paolo Abeni Signed-off-by: Willem de Bruijn Link: https://patch.msgid.link/20260320190148.2409107-1-willemdebruijn.kernel@gmail.com Signed-off-by: Paolo Abeni

net: Provide a PREEMPT_RT specific check for netdev_queue::_xmit_lock

2026-03-05T11:14:21+00:00

After acquiring netdev_queue::_xmit_lock the number of the CPU owning the lock is recorded in netdev_queue::xmit_lock_owner. This works as long as the BH context is not preemptible. On PREEMPT_RT the softirq context is preemptible and without the softirq-lock it is possible to have multiple user in __dev_queue_xmit() submitting a skb on the same CPU. This is fine in general but this means also that the current CPU is recorded as netdev_queue::xmit_lock_owner. This in turn leads to the recursion alert and the skb is dropped. Instead checking the for CPU number, that owns the lock, PREEMPT_RT can check if the lockowner matches the current task. Add netif_tx_owned() which returns true if the current context owns the lock by comparing the provided CPU number with the recorded number. This resembles the current check by negating the condition (the current check returns true if the lock is not owned). On PREEMPT_RT use rt_mutex_owner() to return the lock owner and compare the current task against it. Use the new helper in __dev_queue_xmit() and netif_local_xmit_active() which provides a similar check. Update comments regarding pairing READ_ONCE(). Reported-by: Bert Karwatzki Closes: https://lore.kernel.org/all/20260216134333.412332-1-spasswolf@web.de Fixes: 3253cb49cbad4 ("softirq: Allow to drop the softirq-BKL lock on PREEMPT_RT") Signed-off-by: Sebastian Andrzej Siewior Reported-by: Bert Karwatzki Signed-off-by: Sebastian Andrzej Siewior Link: https://patch.msgid.link/20260302162631.uGUyIqDT@linutronix.de Signed-off-by: Paolo Abeni

net: devmem: use READ_ONCE/WRITE_ONCE on binding->dev

2026-03-05T01:59:27+00:00

binding->dev is protected on the write-side in mp_dmabuf_devmem_uninstall() against concurrent writes, but due to the concurrent bare reads in net_devmem_get_binding() and validate_xmit_unreadable_skb() it should be wrapped in a READ_ONCE/WRITE_ONCE pair to make sure no compiler optimizations play with the underlying register in unforeseen ways. Doesn't present a critical bug because the known compiler optimizations don't result in bad behavior. There is no tearing on u64, and load omissions/invented loads would only break if additional binding->dev references were inlined together (they aren't right now). This just more strictly follows the linux memory model (i.e., "Lock-Protected Writes With Lockless Reads" in tools/memory-model/Documentation/access-marking.txt). Fixes: bd61848900bf ("net: devmem: Implement TX path") Signed-off-by: Bobby Eshleman Link: https://patch.msgid.link/20260302-devmem-membar-fix-v2-1-5b33c9cbc28b@meta.com Signed-off-by: Jakub Kicinski

net: Fix rcu_tasks stall in threaded busypoll

2026-03-03T12:44:28+00:00

I was debugging a NIC driver when I noticed that when I enable threaded busypoll, bpftrace hangs when starting up. dmesg showed: rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 10658 jiffies old. rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 40793 jiffies old. rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 131273 jiffies old. rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 402058 jiffies old. INFO: rcu_tasks detected stalls on tasks: 00000000769f52cd: .N nvcsw: 2/2 holdout: 1 idle_cpu: -1/64 task:napi/eth2-8265 state:R running task stack:0 pid:48300 tgid:48300 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: ? napi_threaded_poll_loop+0x27c/0x2c0 ? __pfx_napi_threaded_poll+0x10/0x10 ? napi_threaded_poll+0x26/0x80 ? kthread+0xfa/0x240 ? __pfx_kthread+0x10/0x10 ? ret_from_fork+0x31/0x50 ? __pfx_kthread+0x10/0x10 ? ret_from_fork_asm+0x1a/0x30 The cause is that in threaded busypoll, the main loop is in napi_threaded_poll rather than napi_threaded_poll_loop, where the latter rarely iterates more than once within its loop. For rcu_softirq_qs_periodic inside napi_threaded_poll_loop to report its qs state, the last_qs must be 100ms behind, and this can't happen because napi_threaded_poll_loop rarely iterates in threaded busypoll, and each time napi_threaded_poll_loop is called last_qs is reset to latest jiffies. This patch changes so that in threaded busypoll, last_qs is saved in the outer napi_threaded_poll, and whether busy_poll_last_qs is NULL indicates whether napi_threaded_poll_loop is called for busypoll. This way last_qs would not reset to latest jiffies on each invocation of napi_threaded_poll_loop. Fixes: c18d4b190a46 ("net: Extend NAPI threaded polling to allow kthread based busy polling") Cc: stable@vger.kernel.org Signed-off-by: YiFei Zhu Reviewed-by: Samiullah Khawaja Link: https://patch.msgid.link/20260227221937.1060857-1-zhuyifei@google.com Signed-off-by: Paolo Abeni