drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)
As advised by Documentation/networking/napi.rst, masking IRQs after
calling napi_schedule can be racy. Avoid this by only masking/scheduling
if napi_schedule_prep returns true. Additionally, since we are running
in an IRQ context we can use the irqoff variant as well.
Fixes: 9e2bc267e780 ("net: axienet: Use NAPI for TX completion path")
Fixes: cc37610caaf8 ("net: axienet: implement NAPI and GRO receive")
Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
---
drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index 9eb300fc3590..4f67072d5149 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -1222,9 +1222,10 @@ static irqreturn_t axienet_tx_irq(int irq, void *_ndev)
u32 cr = lp->tx_dma_cr;
cr &= ~(XAXIDMA_IRQ_IOC_MASK | XAXIDMA_IRQ_DELAY_MASK);
- axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, cr);
-
- napi_schedule(&lp->napi_tx);
+ if (napi_schedule_prep(&lp->napi_tx)) {
+ axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, cr);
+ __napi_schedule_irqoff(&lp->napi_tx);
+ }
}
return IRQ_HANDLED;
@@ -1266,9 +1267,10 @@ static irqreturn_t axienet_rx_irq(int irq, void *_ndev)
u32 cr = lp->rx_dma_cr;
cr &= ~(XAXIDMA_IRQ_IOC_MASK | XAXIDMA_IRQ_DELAY_MASK);
- axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, cr);
-
- napi_schedule(&lp->napi_rx);
+ if (napi_schedule_prep(&lp->napi_rx)) {
+ axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, cr);
+ __napi_schedule_irqoff(&lp->napi_rx);
+ }
}
return IRQ_HANDLED;
--
2.35.1.1320.gc452695387.dirtyOn Mon, 9 Sep 2024 19:19:04 -0400 Sean Anderson wrote: > Additionally, since we are running > in an IRQ context we can use the irqoff variant as well. The _irqoff variant is a bit of a minefield. It causes issues if kernel is built with forced IRQ threading. With datacenter NICs forced threading is never used so we look the other way. Since this is a fix and driver is embedded I reckon we should stick to __napi_schedule(). -- pw-bot: cr
On 9/10/24 21:58, Jakub Kicinski wrote: > On Mon, 9 Sep 2024 19:19:04 -0400 Sean Anderson wrote: >> Additionally, since we are running >> in an IRQ context we can use the irqoff variant as well. > > The _irqoff variant is a bit of a minefield. It causes issues if kernel > is built with forced IRQ threading. With datacenter NICs forced > threading is never used so we look the other way. Since this is a fix > and driver is embedded I reckon we should stick to __napi_schedule(). Does it? __napi_schedule_irqoff selects between __napi_schedule and ____napi_schedule based on whether PREEMPT_RT is enabled. Is there some other way to force IRQ threading? --Sean
On Thu, 12 Sep 2024 10:23:06 -0400 Sean Anderson wrote: > __napi_schedule_irqoff selects between __napi_schedule and > ____napi_schedule based on whether PREEMPT_RT is enabled. Is there some > other way to force IRQ threading? I think so, IIRC threadirqs= kernel boot option lets you do it. I don't remember all the details now :( LMK if I'm wrong
On 9/12/24 11:43, Jakub Kicinski wrote: > On Thu, 12 Sep 2024 10:23:06 -0400 Sean Anderson wrote: >> __napi_schedule_irqoff selects between __napi_schedule and >> ____napi_schedule based on whether PREEMPT_RT is enabled. Is there some >> other way to force IRQ threading? > > I think so, IIRC threadirqs= kernel boot option lets you do it. > I don't remember all the details now :( LMK if I'm wrong Hm, maybe __napi_schedule_irqoff should be updated to take that into account. I will resend without this change. --Sean
On 9/9/2024 4:19 PM, Sean Anderson wrote:
>
> As advised by Documentation/networking/napi.rst, masking IRQs after
> calling napi_schedule can be racy. Avoid this by only masking/scheduling
> if napi_schedule_prep returns true. Additionally, since we are running
> in an IRQ context we can use the irqoff variant as well.
>
> Fixes: 9e2bc267e780 ("net: axienet: Use NAPI for TX completion path")
> Fixes: cc37610caaf8 ("net: axienet: implement NAPI and GRO receive")
> Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>
> ---
>
> drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> index 9eb300fc3590..4f67072d5149 100644
> --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> @@ -1222,9 +1222,10 @@ static irqreturn_t axienet_tx_irq(int irq, void *_ndev)
> u32 cr = lp->tx_dma_cr;
>
> cr &= ~(XAXIDMA_IRQ_IOC_MASK | XAXIDMA_IRQ_DELAY_MASK);
> - axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, cr);
> -
> - napi_schedule(&lp->napi_tx);
> + if (napi_schedule_prep(&lp->napi_tx)) {
> + axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, cr);
> + __napi_schedule_irqoff(&lp->napi_tx);
> + }
> }
>
> return IRQ_HANDLED;
> @@ -1266,9 +1267,10 @@ static irqreturn_t axienet_rx_irq(int irq, void *_ndev)
> u32 cr = lp->rx_dma_cr;
>
> cr &= ~(XAXIDMA_IRQ_IOC_MASK | XAXIDMA_IRQ_DELAY_MASK);
> - axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, cr);
> -
> - napi_schedule(&lp->napi_rx);
> + if (napi_schedule_prep(&lp->napi_rx)) {
> + axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, cr);
> + __napi_schedule_irqoff(&lp->napi_rx);
> + }
> }
>
> return IRQ_HANDLED;
> --
> 2.35.1.1320.gc452695387.dirty
>
>
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