Commit 167053f8 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Jakub Kicinski
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net: Correct wrong BH disable in hard-interrupt. 



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: baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")
Reported-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Tested-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/Yg05duINKBqvnxUc@linutronix.de


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 6ce71687

net/core/dev.c

+8 −3
Original line number Diff line number Diff line
@@ -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)
@@ -4869,12 +4871,15 @@ EXPORT_SYMBOL(__netif_rx); 
 */

int netif_rx(struct sk_buff *skb)

{

	bool need_bh_off = !(hardirq_count() | softirq_count());

	int ret;



	if (need_bh_off)

		local_bh_disable();

	trace_netif_rx_entry(skb);

	ret = netif_rx_internal(skb);

	trace_netif_rx_exit(ret);

	if (need_bh_off)

		local_bh_enable();

	return ret;

}