Re: [PATCH 2/8] idr: fix unexpected id-removal when idr_remove(unallocated_id)

[Tejun Heo]

On Fri, Apr 18, 2014 at 08:49:49PM +0800, Lai Jiangshan wrote:
> If unallocated_id = (ANY * idr_max(idp->layers) + existed_id) is passed

						    existing_id

> to idr_remove(). The existed_id will be removed unexpected.

                       ditto.

> 
> The following test shows this unexpected id-removal:
> 
> static void test4(void)
> {
> 	int id;
> 	DEFINE_IDR(test_idr);
> 
> 	printk(KERN_INFO "Start test4\n");
> 	id = idr_alloc(&test_idr, (void *)1, 42, 43, GFP_KERNEL);
> 	BUG_ON(id != 42);
> 	idr_remove(&test_idr, 42 + IDR_SIZE);
> 	TEST_BUG_ON(idr_find(&test_idr, 42) != (void *)1);
> 	idr_destroy(&test_idr);
> 	printk(KERN_INFO "End of test4\n");
> }
> 
> It only happens when unallocated_id, it is caller's fault. It is not
> a bug. But it is better to add the proper check and complains instead

							complain

> of removing an existed_id silently.

                existing_id

> Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>

Acked-by: Tejun Heo <tj@xxxxxxxxxx>

Thanks.

-- 
tejun
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