linux-kernel - Re: [RFC PATCH v2 4/4] of: move of_get_cpu_node implementation to DT core library

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 19 Aug 2013 14:24:20 +0100
From:	Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@....com>
To:	Rob Herring <robherring2@...il.com>
CC:	Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@....com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	Jonas Bonn <jonas@...thpole.se>,
	Michal Simek <monstr@...str.eu>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>
Subject: Re: [RFC PATCH v2 4/4] of: move of_get_cpu_node implementation to
 DT core library

On 19/08/13 14:11, Rob Herring wrote:
> On 08/16/2013 12:39 PM, Sudeep KarkadaNagesha wrote:
>> From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@....com>
>>
>> This patch moves the generalized implementation of of_get_cpu_node from
>> PowerPC to DT core library, thereby adding support for retrieving cpu
>> node for a given logical cpu index on any architecture.
>>
>> The CPU subsystem can now use this function to assign of_node in the
>> cpu device while registering CPUs.
>>
>> It is recommended to use these helper function only in pre-SMP/early
>> initialisation stages to retrieve CPU device node pointers in logical
>> ordering. Once the cpu devices are registered, it can be retrieved easily
>> from cpu device of_node which avoids unnecessary parsing and matching.
>>
>> Cc: Rob Herring <rob.herring@...xeda.com>
>> Cc: Grant Likely <grant.likely@...aro.org>
>> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
>> Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@....com>
> 
> [snip]
> 
>> +/**
>> + * of_get_cpu_node - Get device node associated with the given logical CPU
>> + *
>> + * @cpu: CPU number(logical index) for which device node is required
>> + * @thread: if not NULL, local thread number within the physical core is
>> + *          returned
>> + *
>> + * The main purpose of this function is to retrieve the device node for the
>> + * given logical CPU index. It should be used to initialize the of_node in
>> + * cpu device. Once of_node in cpu device is populated, all the further
>> + * references can use that instead.
>> + *
>> + * CPU logical to physical index mapping is architecture specific and is built
>> + * before booting secondary cores. This function uses arch_match_cpu_phys_id
>> + * which can be overridden by architecture specific implementation.
>> + *
>> + * Returns a node pointer for the logical cpu if found, else NULL.
>> + */
>> +struct device_node *of_get_cpu_node(int cpu, unsigned int *thread)
>> +{
>> +	struct device_node *cpun, *cpus;
>> +
>> +	cpus = of_find_node_by_path("/cpus");
>> +	if (!cpus) {
>> +		pr_warn("Missing cpus node, bailing out\n");
>> +		return NULL;
>> +	}
>> +
>> +	for_each_child_of_node(cpus, cpun) {
>> +		if (of_node_cmp(cpun->type, "cpu"))
>> +			continue;
>> +#ifdef CONFIG_PPC
> 
> You don't really need this ifdef as this function should never succeed
> on other arches. Alternatively, you can use "IS_ENABLED(CONFIG_PPC)"
> instead.
> 
Agreed, I can remove it as long as no other architecture use that
property. It's just to avoid checking for it on other architectures.
I will use IS_ENABLED as you suggested.

> Otherwise,
> 
> Acked-by: Rob Herring <rob.herring@...xeda.com>
> 
Thanks.

Regards,
Sudeep


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/