quoted

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Please try instead this patch :

diff --git a/net/core/dev.c b/net/core/dev.c

index
5d43e010ef870a6ab92895297fe18d6e6a03593a..baa4bff9a6fbe0d77d7921865c038060cb5efffd
100644

--- a/net/core/dev.c
+++ b/net/core/dev.c

@@ -4320,9 +4320,8 @@ static void

net_rps_action_and_irq_enable(struct

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softnet_data *sd)
 		while (remsd) {
 			struct softnet_data *next = remsd->rps_ipi_next;

-			if (cpu_online(remsd->cpu))
-				smp_call_function_single_async(remsd->cpu,
-							   &remsd->csd);
+			smp_call_function_single_async(remsd->cpu,
+						       &remsd->csd);
 			remsd = next;
 		}
 	} else

Hi Eric

While the original issue of data stall due to missing IPI is no longer
seen with netif_rx_ni(), the scenario of rps cpu online in [1 -
get_rps_cpus] but offline in [2 - net_rps_action_and_irq_enable] could
still occur. Using your patch, triggering an IPI on an offline cpu in [2]
leads to a crash on my arch.

I would like to know your thoughts on how to fix this race. Could the
patch which I had initially proposed help here. Alternatively, is it
correct to reset NAPI state and increment dropped sd count if an offline
CPU is detected in [2].

--
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
Foundation Collaborative Project