From: Sebastian Andrzej Siewior Date: Wed, 2 Oct 2024 12:58:37 +0000 (+0200) Subject: sfc: Don't invoke xdp_do_flush() from netpoll. X-Git-Tag: v6.12-rc3~22^2~45 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=55e802468e1d38dec8e25a2fdb6078d45b647e8c;p=thirdparty%2Fkernel%2Flinux.git sfc: Don't invoke xdp_do_flush() from netpoll. 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 Closes: https://lore.kernel.org/5627f6d1-5491-4462-9d75-bc0612c26a22@app.fastmail.com Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Edward Cree Link: https://patch.msgid.link/20241002125837.utOcRo6Y@linutronix.de Signed-off-by: Jakub Kicinski --- 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) &&