linux-kernel - Re: [PATCH] driver: make dev_set

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Date:	Tue, 28 Apr 2009 08:14:13 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Greg KH <gregkh@...e.de>
CC:	Ingo Molnar <mingo@...e.hu>, Kay Sievers <kay.sievers@...y.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-pci@...r.kernel.org
Subject: Re: [PATCH] driver: make dev_set_name(, NULL) work

Greg KH wrote:
> On Tue, Apr 28, 2009 at 12:36:06AM -0700, Yinghai Lu wrote:
>> while looking dev_set_name() calling, there is one
>> 	dev_set_name(&dev->dev, NULL)
>> to used to try to free the device name, before kfree that device.
> 
> What's wrong with that?
> 
>> need to move the check for device_add in
>> | commit 8a577ffc75d9194fe8cdb7479236f2081c26ca1f
>> | Author: Kay Sievers <kay.sievers@...y.org>
>> | Date:   Sat Apr 18 15:05:45 2009 -0700
>> |
>> |    driver: dont update dev_name via device_add path
>> from kobject_set_name_vargs to kobject_add_vargs instead.
>>
>> in kobject_set_name_vargs will check if fmt is NULL.
>>
>> actually we need to use dev_set_name(,NULL) later on failing path
>> and release to prevent leaking
> 
> Are you sure?
> 
> confused,
> 

in arch/arm/common/sa111.c


static int
sa1111_init_one_child(struct sa1111 *sachip, struct resource *parent,
                      struct sa1111_dev_info *info)
{
        struct sa1111_dev *dev;
        int ret;

        dev = kzalloc(sizeof(struct sa1111_dev), GFP_KERNEL);
        if (!dev) {
                ret = -ENOMEM;
                goto out;
        }

        dev_set_name(&dev->dev, "%4.4lx", info->offset);
        dev->devid       = info->devid;
        dev->dev.parent  = sachip->dev;
        dev->dev.bus     = &sa1111_bus_type;
        dev->dev.release = sa1111_dev_release;
        dev->dev.coherent_dma_mask = sachip->dev->coherent_dma_mask;
        dev->res.start   = sachip->phys + info->offset;
        dev->res.end     = dev->res.start + 511;
        dev->res.name    = dev_name(&dev->dev);
        dev->res.flags   = IORESOURCE_MEM;
        dev->mapbase     = sachip->base + info->offset;
        dev->skpcr_mask  = info->skpcr_mask;
        memmove(dev->irq, info->irq, sizeof(dev->irq));

        ret = request_resource(parent, &dev->res);
        if (ret) {
                printk("SA1111: failed to allocate resource for %s\n",
                        dev->res.name);
                dev_set_name(&dev->dev, NULL);
                kfree(dev);
                goto out;
        }


when first dev_set_name is called, dev->dev.kobj.name will initialized from kmalloc.
so before kfree(dev), do we need to kfree that name?

YH
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