Hi Andrzej,
On 16.02.2022 18:50, Sebastian Andrzej Siewior wrote:
> I missed the obvious case where netif_ix() is invoked from hard-IRQ
> context.
>
> Disabling bottom halves is only needed in process context. This ensures
> that the code remains on the current CPU and that the soft-interrupts
> are processed at local_bh_enable() time.
> In hard- and soft-interrupt context this is already the case and the
> soft-interrupts will be processed once the context is left (at irq-exit
> time).
>
> Disable bottom halves if neither hard-interrupts nor soft-interrupts are
> disabled. Update the kernel-doc, mention that interrupts must be enabled
> if invoked from process context.
>
> Fixes: baebdf48c3600 ("net: dev: Makes sure netif_rx() can be invoked in any context.")
> Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> ---
> Marek, does this work for you?
Yes, this fixed the issue. Thanks!
Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> net/core/dev.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 909fb38159108..87729491460fc 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -4860,7 +4860,9 @@ EXPORT_SYMBOL(__netif_rx);
> * congestion control or by the protocol layers.
> * The network buffer is passed via the backlog NAPI device. Modern NIC
> * driver should use NAPI and GRO.
> - * This function can used from any context.
> + * This function can used from interrupt and from process context. The
> + * caller from process context must not disable interrupts before invoking
> + * this function.
> *
> * return values:
> * NET_RX_SUCCESS (no congestion)
> @@ -4870,12 +4872,15 @@ EXPORT_SYMBOL(__netif_rx);
> int netif_rx(struct sk_buff *skb)
> {
> int ret;
> + bool need_bh_off = !(hardirq_count() | softirq_count());
>
> - local_bh_disable();
> + if (need_bh_off)
> + local_bh_disable();
> trace_netif_rx_entry(skb);
> ret = netif_rx_internal(skb);
> trace_netif_rx_exit(ret);
> - local_bh_enable();
> + if (need_bh_off)
> + local_bh_enable();
> return ret;
> }
> EXPORT_SYMBOL(netif_rx);
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
