linux-kernel - Re: [RFC v5 1/8] platform/x86: intel_pmc_ipc: Use spin

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Date:   Sun, 8 Oct 2017 11:54:13 -0700
From:   "Kuppuswamy, Sathyanarayanan" <sathyaosid@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc:     Alessandro Zummo <a.zummo@...ertech.it>,
        "x86@...nel.org" <x86@...nel.org>,
        Wim Van Sebroeck <wim@...ana.be>,
        Ingo Molnar <mingo@...hat.com>,
        Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
        Zha Qipeng <qipeng.zha@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "dvhart@...radead.org" <dvhart@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Lee Jones <lee.jones@...aro.org>,
        Andy Shevchenko <andy@...radead.org>,
        Souvik Kumar Chakravarty <souvik.k.chakravarty@...el.com>,
        linux-rtc@...r.kernel.org, linux-watchdog@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kupuswamy@...ux.intel.com>
Subject: Re: [RFC v5 1/8] platform/x86: intel_pmc_ipc: Use spin_lock to
 protect GCR updates

Hi Andy,


On 10/8/2017 11:38 AM, Andy Shevchenko wrote:
> On Sun, Oct 8, 2017 at 1:19 AM,
> <sathyanarayanan.kuppuswamy@...ux.intel.com> wrote:
>> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
>>
>> Currently, update_no_reboot_bit() function implemented in this driver
>> uses mutex_lock() to protect its register updates. But this function is
>> called with in atomic context in iTCO_wdt_start() and iTCO_wdt_stop()
>> functions in iTCO_wdt.c driver, which in turn causes "sleeping into
>> atomic context" issue. This patch fixes this issue by replacing the
>> mutex_lock() with spin_lock() to protect the GCR read/write/update APIs.
>>
>> Fixes: 9d855d4 ("platform/x86: intel_pmc_ipc: Fix iTCO_wdt GCS memory mapping failure")
>> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kupuswamy@...ux.intel.com>
>>   * Rebased this patch on top of Andy's review branch.
> Oh, what I asked you is to use vanilla kernel as a base.
> Please, be sure (you assured me, though it's not true)
I did test this patch on top of 4.14-rc3, but I have included another 
patch (""platform/x86: intel_pmc_ipc: Use devm_* calls in driver probe 
function") from your review branch before testing.
I assumed that your will be pushing this patch along with devm_* fixes 
patch (since you already reviewed it), So I re-based them together on 
top of 4.14-rc3.  Sorry, it looks like my assumption is incorrect.
>   that it's
> applied against vanilla (or our fixes branch) and send just this one
> patch separately.
I will send it separately now.
>
> No need to resend v5 right now.
>