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SubjectRe: [PATCH 01/10] Fix idr_remove()
Andrew Morton wrote:
> On Tue, 29 Apr 2008 16:33:05 +0200
> Nadia.Derbey@bull.net wrote:
>
>
>>[PATCH 01/10]
>>
>>This patch fixes idr_remove(): the return inside the loop makes us free only
>>a single layer.
>>
>>Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
>>
>>---
>> lib/idr.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>>Index: linux-2.6.25-mm1/lib/idr.c
>>===================================================================
>>--- linux-2.6.25-mm1.orig/lib/idr.c 2008-04-25 15:29:00.000000000 +0200
>>+++ linux-2.6.25-mm1/lib/idr.c 2008-04-25 15:48:34.000000000 +0200
>>@@ -385,8 +385,8 @@ void idr_remove(struct idr *idp, int id)
>> while (idp->id_free_cnt >= IDR_FREE_MAX) {
>> p = alloc_layer(idp);
>> kmem_cache_free(idr_layer_cache, p);
>>- return;
>> }
>>+ return;
>> }
>> EXPORT_SYMBOL(idr_remove);
>
>
> erk, ancient bug.
>
> I _think_ the implications of this are that an idr tree will grow fatter
> than it needs to be, but there is no permanent leak: idr_destroy() will
> still free everything, yes?

Yes, exactly. Actually, I've not checked whether all the kernel
components call idr_destroy() when needed.

>
> And a consequence of the fix is that idr manipulations will now result in
> more allocs and frees,

Not necessarily more allocs: this loop keeps IDR_FREE_MAX layers in the
free list. So idr_pre_get() should be a noop.

> but the amount of memory which a tree uses will be
> less?
>
>
>

Regards,
Nadia




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