Re: [PATCH] rtlwifi: rtl8192x: Enabling and disabling hardware interrupts after enabling local irq flags

[Larry Finger]

On 01/20/2017 08:14 AM, Bharat Kumar Gogada wrote:
>  > On 01/19/2017 04:14 AM, Bharat Kumar Gogada wrote:
> > > -Realtek 8192CE chipset maintains local irq flags after enabling/disabling
> > > hardware interrupts.
> > > -Hardware interrupts are enabled before enabling the local irq
> > > flags(these flags are being checked in interrupt handler),
> > > leading to race condition on some RP, where the irq line between
> > > bridge and GIC goes high at ASSERT_INTx and goes low only
> > > at DEASSERT_INTx. In this kind of RP by the time ASSERT_INTx is seen
> > > irq_enable flag is still set to false, resulting in continuous
> > > interrupts seen by CPU as DEASSERT_INTx cannot be sent since
> > > flag is still false and making CPU stall.
> > > -Changing the sequence of setting these irq flags.
> > >
> > > Signed-off-by: Bharat Kumar Gogada <bharatku@xxxxxxxxxx>
> > > ---
> >
> > This patch should be enhanced with the smb_xx() calls as suggested by by Lino.
> >
> > The subject should be changed. I would suggest something like "rtlwifi:
> > rtl8192ce: Prevent race condition when enabling interrupts", as it explains the
> > condition you are preventing.
> >
> > The other PCI drivers also have the same problem. Do you want to prepare the
> > patches, or should I do it?
> Thanks Larry. Please send out the patches adding the above enhancements suggested by Lino.

I have prepared a patch fixing all the drivers. By the way, what CPU hardware 
showed this problem?

Larry