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net: tc35815: rework network interface interrupt logic

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Rework network interface logic. Before this change, the code flow was:
1. Disable interrupt
2. Try to schedule a NAPI
3. Check if it was possible (NAPI is not already scheduled)
4. emit BUG() if we receive interrupt while a NAPI is scheduled

If some application busy poll or set gro_flush_timeout low enough, it's
possible to reach the BUG() condition. Given that the condition may
happen and it wouldn't be a bug, rework the logic to permit such case
and prevent stall with interrupt never enabled again.

Disable the interrupt only if the NAPI can be scheduled (aka it's not
already scheduled) and drop the printk and BUG() call. With these
change, in the event of a NAPI already scheduled, the interrupt is
simply ignored with nothing done.

Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Link: https://lore.kernel.org/r/20231009133754.9834-4-ansuelsmth@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Christian Marangi 2023-10-09 15:37:53 +02:00 committed by Jakub Kicinski
parent 73382e919f
commit be176234d0
1 changed files with 3 additions and 7 deletions
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10
drivers/net/ethernet/toshiba/tc35815.c
View File

@ -1434,14 +1434,10 @@ static irqreturn_t tc35815_interrupt(int irq, void *dev_id)
u32 dmactl = tc_readl(&tr->DMA_Ctl);
if (!(dmactl & DMA_IntMask)) {
/* disable interrupts */
tc_writel(dmactl | DMA_IntMask, &tr->DMA_Ctl);
if (napi_schedule_prep(&lp->napi))
if (napi_schedule_prep(&lp->napi)) {
/* disable interrupts */
tc_writel(dmactl | DMA_IntMask, &tr->DMA_Ctl);
__napi_schedule(&lp->napi);
else {
printk(KERN_ERR "%s: interrupt taken in poll\n",
dev->name);
BUG();
}
(void)tc_readl(&tr->Int_Src); /* flush */
return IRQ_HANDLED;