linux-kernel - RE: [PATCH] rtlwifi: rtl8192x: Enabling and disabling hardware interrupts after enabling local irq flags

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Message-ID: <8520D5D51A55D047800579B094147198263CA86D@XAP-PVEXMBX02.xlnx.xilinx.com>
Date:   Fri, 20 Jan 2017 14:14:10 +0000
From:   Bharat Kumar Gogada <bharat.kumar.gogada@...inx.com>
To:     Larry Finger <Larry.Finger@...inger.net>,
        "chaoming_li@...lsil.com.cn" <chaoming_li@...lsil.com.cn>,
        "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "kvalo@...eaurora.org" <kvalo@...eaurora.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Ravikiran Gummaluri <rgummal@...inx.com>
Subject: RE: [PATCH] rtlwifi: rtl8192x: Enabling and disabling hardware
 interrupts after enabling local irq flags

 > 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@...inx.com>
> > ---
> 
> 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.

Bharat