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net: Correct wrong BH disable in hard-interrupt.

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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: baebdf48c3 ("net: dev: Makes sure netif_rx() can be invoked in any context.")
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/Yg05duINKBqvnxUc@linutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Sebastian Andrzej Siewior 2022-02-16 18:50:46 +01:00 committed by Jakub Kicinski
parent 6ce71687d4
commit 167053f8dd
1 changed files with 8 additions and 3 deletions
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11
net/core/dev.c
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@ -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)
@ -4869,13 +4871,16 @@ EXPORT_SYMBOL(__netif_rx);
*/
int netif_rx(struct sk_buff *skb)
{
bool need_bh_off = !(hardirq_count() | softirq_count());
int ret;
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);