linux-kernel - Re: [PATCH] drivers: stm: correct the index in master array release

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Message-ID: <87bn7iclel.fsf@ashishki-desk.ger.corp.intel.com>
Date:	Mon, 15 Feb 2016 12:34:10 +0200
From:	Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:	Chunyan Zhang <zhang.chunyan@...aro.org>
Cc:	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
	Mathieu Poirier <mathieu.poirier@...aro.org>,
	Lyra Zhang <zhang.lyra@...il.com>
Subject: Re: [PATCH] drivers: stm: correct the index in master array release

Chunyan Zhang <zhang.chunyan@...aro.org> writes:

> On Tue, Feb 9, 2016 at 6:12 PM, Alexander Shishkin
> <alexander.shishkin@...ux.intel.com> wrote:
>> Chunyan Zhang <zhang.chunyan@...aro.org> writes:
>>
>>> It would be broken if stm_data->sw_start isn't zero, because that
>>> stp_master_free() get the 'master' with __stm_master()/stm_master(),
>>> in which the masterID is the second input parameter minus
>>> stm_data->sw_start. So freeing STM masters has to start from
>>> stm_data->sw_start.
>>
>> No, it won't. stm_master_free() handles nonexistent masters correctly.
>> It does make sense to shrink the loop in stm_unregister_device() to
>> avoid going through the [0..sw_start) range, since stm_master() returns
>> NULL for those, but not for the reasons given in this patch description.
>
> Let's assume sw_start = 64, sw_end = 79, sw_nmasters should be 16, if
> the loop goes through [0..16), the existed masters will not be freed.

Ah yes, you're right, of course.

I'll add this fix to the queue with a proper description.

Thanks,
--
Alex