netdev - RE: [PATCH net] bnx2x: prevent WARN during driver unload

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Date:	Wed, 8 Jan 2014 07:05:36 +0000
From:	Yuval Mintz <yuvalmin@...adcom.com>
To:	David Miller <davem@...emloft.net>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Dmitry Kravkov <dmitry@...adcom.com>,
	Ariel Elior <ariele@...adcom.com>
Subject: RE: [PATCH net] bnx2x: prevent WARN during driver unload

> >>
> >> > +	fp->state &= BNX2X_FP_STATE_DISABLED;
> >>  ...
> >> > +	fp->state &= BNX2X_FP_STATE_DISABLED;
> >>
> >> Surely you mean "&= ~BNX2X_FP_STATE_DISABLED" here?
> >
> > Thought the comment above the code was sufficient to show
> > this is intentional.
> >
> > The BNX2X_FP_STATE_DISABLED will cause BNX@...P_LOCKED to
> > Be true. The bnx2x_fp_ll_disable() works by setting this bit even
> > when BNX2X_FP_OWNED is set; while other flows release the lock
> > the will clear the bit indications except for the disabled indication,
> > so that no other flow could take the lock after it was disabled,
> > and the loop of bnx2x_fp_ll_disable() calls will eventually return true.
> 
> This bit handling is completely unintuitive.
> 
> The way a boolean state works is you manage it by setting it when
> a condition arises, and clear it when a condition goes away.

True; but we didn't reach this bit of intuitive code on our own -
this is practically a porting of 27d9ce3f "ixgbe: fix qv_lock_napi
call in ixgbe_napi_disable_all" into the bnx2x driver.
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