[PATCH net] net: stmmac: use __napi_schedule() for PREEMPT_RT

Subsystems: networking drivers, stmmac ethernet driver, the rest

STALE2028d LANDED

Landed in mainline as 1f02efd1bb35 on 2021-01-13.

2 messages, 2 authors, 2021-01-14 · open the first message on its own page

[PATCH net] net: stmmac: use __napi_schedule() for PREEMPT_RT

From: Sebastien Laveze <hidden>
Date: 2021-01-12 14:04:29

From: Seb Laveze <redacted>

Use of __napi_schedule_irqoff() is not safe with PREEMPT_RT in which
hard interrupts are not disabled while running the threaded interrupt.

Using __napi_schedule() works for both PREEMPT_RT and mainline Linux,
just at the cost of an additional check if interrupts are disabled for
mainline (since they are already disabled).

Similar to the fix done for enetc:
215602a8d212 ("enetc: use napi_schedule to be compatible with PREEMPT_RT")

Signed-off-by: Seb Laveze <redacted>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 5b1c12ff98c0..2d90d6856ec5 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2184,7 +2184,7 @@ static int stmmac_napi_check(struct stmmac_priv *priv, u32 chan)
 			spin_lock_irqsave(&ch->lock, flags);
 			stmmac_disable_dma_irq(priv, priv->ioaddr, chan, 1, 0);
 			spin_unlock_irqrestore(&ch->lock, flags);
-			__napi_schedule_irqoff(&ch->rx_napi);
+			__napi_schedule(&ch->rx_napi);
 		}
 	}
 
@@ -2193,7 +2193,7 @@ static int stmmac_napi_check(struct stmmac_priv *priv, u32 chan)
 			spin_lock_irqsave(&ch->lock, flags);
 			stmmac_disable_dma_irq(priv, priv->ioaddr, chan, 0, 1);
 			spin_unlock_irqrestore(&ch->lock, flags);
-			__napi_schedule_irqoff(&ch->tx_napi);
+			__napi_schedule(&ch->tx_napi);
 		}
 	}
 
-- 
2.25.1


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Re: [PATCH net] net: stmmac: use __napi_schedule() for PREEMPT_RT

From: Jakub Kicinski <kuba@kernel.org>
Date: 2021-01-14 01:51:44

On Tue, 12 Jan 2021 15:01:22 +0100 Sebastien Laveze wrote:
From: Seb Laveze <redacted>

Use of __napi_schedule_irqoff() is not safe with PREEMPT_RT in which
hard interrupts are not disabled while running the threaded interrupt.

Using __napi_schedule() works for both PREEMPT_RT and mainline Linux,
just at the cost of an additional check if interrupts are disabled for
mainline (since they are already disabled).

Similar to the fix done for enetc:
215602a8d212 ("enetc: use napi_schedule to be compatible with PREEMPT_RT")

Signed-off-by: Seb Laveze <redacted>
Fixed up the commit message to appease checkpatch and applied, thanks!

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