netdev - RE: [PATCH net] bnx2x: Fix netpoll interoperability

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Date:	Tue, 14 Apr 2015 16:44:22 +0000
From:	Yuval Mintz <Yuval.Mintz@...gic.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>, "bind@...s.net" <bind@...s.net>,
	"peter@...leysoftware.com" <peter@...leysoftware.com>,
	Ariel Elior <Ariel.Elior@...gic.com>,
	"Willem de Bruijn" <willemb@...gle.com>
Subject: RE: [PATCH net] bnx2x: Fix netpoll interoperability

>> Commit 9a2620c877454 ("bnx2x: prevent WARN during driver unload") switched
>> the napi/busy_lock locking mechanism from spin_lock() into spin_lock_bh(),
>> breaking inter-operability with netconsole, as netpoll disables interrupts
>> prior to calling our napi mechanism.
>>
>> This switches the driver into using atomic assignments instead of the spinlock
>> mechanisms previously employed.

> This fix is prone to starvation of softirq handler.
> Since you use 2 bits, I believe you could set one bit unconditionally to
> make sure the bnx2x_low_latency_recv() will yield to softirq handler.

Care to elaborate a bit? About the possibly starvation?

> Please CC me and Willem on busypoll stuff, thanks !

Sure.

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