linux-kernel - Re: [PATCH 2/3] of: Support hashtable lookups for phandles

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Message-ID: <CAL_JsqLsztrWr8mQwCHzA+qkrRev0Kfr--BkMiPVRVycZp0A=Q@mail.gmail.com>
Date:	Mon, 9 May 2016 16:11:28 -0500
From:	Rob Herring <robherring2@...il.com>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Pantelis Antoniou <pantelis.antoniou@...sulko.com>
Cc:	Frank Rowand <frowand.list@...il.com>,
	Matt Porter <mporter@...sulko.com>,
	Grant Likely <grant.likely@...retlab.ca>,
	Koen Kooi <koen@...inion.thruhere.net>,
	Guenter Roeck <linux@...ck-us.net>,
	Marek Vasut <marex@...x.de>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Pantelis Antoniou <panto@...oniou-consulting.com>
Subject: Re: [PATCH 2/3] of: Support hashtable lookups for phandles

On Mon, May 9, 2016 at 3:38 PM, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> Hi Pantelis,
>
> On Mon, May 9, 2016 at 8:11 PM, Pantelis Antoniou
> <pantelis.antoniou@...sulko.com> wrote:
>> --- a/drivers/of/base.c
>> +++ b/drivers/of/base.c
>
>> @@ -1073,9 +1097,14 @@ struct device_node *of_find_node_by_phandle(phandle handle)
>>                 return NULL;
>>
>>         raw_spin_lock_irqsave(&devtree_lock, flags);
>> -       for_each_of_allnodes(np)
>> -               if (np->phandle == handle)
>> -                       break;
>> +       /* when we're ready use the hash table */
>> +       if (of_phandle_ht_available() && !in_interrupt())
>
> I guess the !in_interrupt() test is because of the locking inside
> rhashtable_lookup_fast()?

Not a use we should support. Just warn for anyone parsing DT in
interrupt context.

Rob