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idr: make idr_destroy() imply idr_remove_all() 

idr is silly in quite a few ways, one of which is how it's supposed to
be destroyed - idr_destroy() doesn't release IDs and doesn't even whine
if the idr isn't empty.  If the caller forgets idr_remove_all(), it
simply leaks memory.

Even ida gets this wrong and leaks memory on destruction.  There is
absoltely no reason not to call idr_remove_all() from idr_destroy().
Nobody is abusing idr_destroy() for shrinking free layer buffer and
continues to use idr after idr_destroy(), so it's safe to do remove_all
from destroy.

In the whole kernel, there is only one place where idr_remove_all() is
legitimiately used without following idr_destroy() while there are quite
a few places where the caller forgets either idr_remove_all() or
idr_destroy() leaking memory.

This patch makes idr_destroy() call idr_destroy_all() and updates the
function description accordingly.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Tejun Heo 2013-02-27 17:03:35 -08:00 committed by Linus Torvalds
parent 6cdae7416a
commit 9bb26bc1ff
1 changed files with 11 additions and 9 deletions
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20
lib/idr.c
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@ -436,15 +436,6 @@ EXPORT_SYMBOL(idr_remove);
/**
* idr_remove_all - remove all ids from the given idr tree
* @idp: idr handle
*
* idr_destroy() only frees up unused, cached idp_layers, but this
* function will remove all id mappings and leave all idp_layers
* unused.
*
* A typical clean-up sequence for objects stored in an idr tree will
* use idr_for_each() to free all objects, if necessay, then
* idr_remove_all() to remove all ids, and idr_destroy() to free
* up the cached idr_layers.
*/
void idr_remove_all(struct idr *idp)
{
@ -484,9 +475,20 @@ EXPORT_SYMBOL(idr_remove_all);
/**
* idr_destroy - release all cached layers within an idr tree
* @idp: idr handle
*
* Free all id mappings and all idp_layers. After this function, @idp is
* completely unused and can be freed / recycled. The caller is
* responsible for ensuring that no one else accesses @idp during or after
* idr_destroy().
*
* A typical clean-up sequence for objects stored in an idr tree will use
* idr_for_each() to free all objects, if necessay, then idr_destroy() to
* free up the id mappings and cached idr_layers.
*/
void idr_destroy(struct idr *idp)
{
idr_remove_all(idp);
while (idp->id_free_cnt) {
struct idr_layer *p = get_from_free_list(idp);
kmem_cache_free(idr_layer_cache, p);