| Message ID | 20241002125837.utOcRo6Y@linutronix.de (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 55e802468e1d38dec8e25a2fdb6078d45b647e8c |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] sfc: Don't invoke xdp_do_flush() from netpoll. | expand |
On 02/10/2024 13:58, Sebastian Andrzej Siewior wrote: > Yury reported a crash in the sfc driver originated from > netpoll_send_udp(). The netconsole sends a message and then netpoll > invokes the driver's NAPI function with a budget of zero. It is > dedicated to allow driver to free TX resources, that it may have used > while sending the packet. > > In the netpoll case the driver invokes xdp_do_flush() unconditionally, > leading to crash because bpf_net_context was never assigned. > > Invoke xdp_do_flush() only if budget is not zero. > > Fixes: 401cb7dae8130 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.") > Reported-by: Yury Vostrikov <mon@unformed.ru> > Closes: https://lore.kernel.org/5627f6d1-5491-4462-9d75-bc0612c26a22@app.fastmail.com > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Reviewed-by: Edward Cree <ecree.xilinx@gmail.com>
On Wed, 2 Oct 2024 14:58:37 +0200 Sebastian Andrzej Siewior wrote:
> Fixes: 401cb7dae8130 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.")
FTR I think this could have imploded even before, just a lot lower
probability.
Hello: This patch was applied to netdev/net.git (main) by Jakub Kicinski <kuba@kernel.org>: On Wed, 2 Oct 2024 14:58:37 +0200 you wrote: > Yury reported a crash in the sfc driver originated from > netpoll_send_udp(). The netconsole sends a message and then netpoll > invokes the driver's NAPI function with a budget of zero. It is > dedicated to allow driver to free TX resources, that it may have used > while sending the packet. > > In the netpoll case the driver invokes xdp_do_flush() unconditionally, > leading to crash because bpf_net_context was never assigned. > > [...] Here is the summary with links: - [net] sfc: Don't invoke xdp_do_flush() from netpoll. https://git.kernel.org/netdev/net/c/55e802468e1d You are awesome, thank you!
diff --git a/drivers/net/ethernet/sfc/efx_channels.c b/drivers/net/ethernet/sfc/efx_channels.c index c9e17a8208a90..f1723a6fb082b 100644 --- a/drivers/net/ethernet/sfc/efx_channels.c +++ b/drivers/net/ethernet/sfc/efx_channels.c @@ -1260,7 +1260,8 @@ static int efx_poll(struct napi_struct *napi, int budget) spent = efx_process_channel(channel, budget); - xdp_do_flush(); + if (budget) + xdp_do_flush(); if (spent < budget) { if (efx_channel_has_rx_queue(channel) && diff --git a/drivers/net/ethernet/sfc/siena/efx_channels.c b/drivers/net/ethernet/sfc/siena/efx_channels.c index a7346e965bfe7..d120b3c83ac07 100644 --- a/drivers/net/ethernet/sfc/siena/efx_channels.c +++ b/drivers/net/ethernet/sfc/siena/efx_channels.c @@ -1285,7 +1285,8 @@ static int efx_poll(struct napi_struct *napi, int budget) spent = efx_process_channel(channel, budget); - xdp_do_flush(); + if (budget) + xdp_do_flush(); if (spent < budget) { if (efx_channel_has_rx_queue(channel) &&
Yury reported a crash in the sfc driver originated from netpoll_send_udp(). The netconsole sends a message and then netpoll invokes the driver's NAPI function with a budget of zero. It is dedicated to allow driver to free TX resources, that it may have used while sending the packet. In the netpoll case the driver invokes xdp_do_flush() unconditionally, leading to crash because bpf_net_context was never assigned. Invoke xdp_do_flush() only if budget is not zero. Fixes: 401cb7dae8130 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.") Reported-by: Yury Vostrikov <mon@unformed.ru> Closes: https://lore.kernel.org/5627f6d1-5491-4462-9d75-bc0612c26a22@app.fastmail.com Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- drivers/net/ethernet/sfc/efx_channels.c | 3 ++- drivers/net/ethernet/sfc/siena/efx_channels.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-)