linux-kernel - Re: [PATCH] drivers: usb: host: Fix GFP

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Date:   Fri, 22 Dec 2017 13:20:54 +0530
From:   Shrikant Maurya <shrikant.maurya@...hveda.org>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     ok@...ecdesign.ee, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, Suniel Mahesh <sunil.m@...hveda.org>,
        Raghu Bharadwaj <raghu@...hveda.org>,
        Karthik Tummala <karthik@...hveda.org>
Subject: Re: [PATCH] drivers: usb: host: Fix GFP_KERNEL in spinlock context



On Friday 22 December 2017 12:43 PM, Greg KH wrote:
> On Fri, Dec 22, 2017 at 11:19:24AM +0530, shrikant.maurya@...hveda.org wrote:
>> From: Shrikant Maurya <shrikant.maurya@...hveda.org>
>>
>> As reported by Jia-Ju Bai (https://lkml.org/lkml/2017/12/11/872):
>> API's are using GFP_KERNEL to allocate memory, which may sleep.
>> To ensure atomicity such allocations must be avoided in critical
>> sections under spinlock.
>> Fixed by moving part of the code which is using GFP_KERNEL for
>> memory allocation out of spinlock.
>>
>> Reported-by: Jia-Ju Bai <baijiaju1990@...il.com>
>> Signed-off-by: Shrikant Maurya <shrikant.maurya@...hveda.org>
>> Signed-off-by: Suniel Mahesh <sunil.m@...hveda.org>
>> Signed-off-by: Raghu Bharadwaj <raghu@...hveda.org>
>> Signed-off-by: Karthik Tummala <karthik@...hveda.org>
>> ---
>> Note:
>> - trace of device_init_wakeup() leads to creation of a struct
>>   wakeup_source object and addition of the object to the list
>>   of wakeup sources. While allocating wakeup_source object, API
>>   is using GFP_KERNEL. This particular section is removed out of
>>   spinlock.
>> - Changeset was compile tested and built(ARCH=arm) on linux-next
>>   (latest).
>> - No build issues reported.
>> - Changeset was not tested on hardware.
> No one was able to test on the hardware itself?  Ideally I'd like to see
> that happen to verify nothing breaks here.  No one has this chip on any
> devices?
>
> thanks,
Sorry Greg, we dont have the chip / hardware, and we are aware that it should
be hardware tested. we were looking at the software aspect.

thanks,
shrikanth
> greg k-h