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

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Message-ID: <b2e783f6-fa09-e287-8119-266299cdae22@lwfinger.net>
Date:   Thu, 19 Jan 2017 20:41:27 -0600
From:   Larry Finger <Larry.Finger@...inger.net>
To:     Bharat Kumar Gogada <bharat.kumar.gogada@...inx.com>,
        chaoming_li@...lsil.com.cn, linux-wireless@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     kvalo@...eaurora.org, netdev@...r.kernel.org, rgummal@...inx.com,
        Bharat Kumar Gogada <bharatku@...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?

Larry