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Commit 9bb26bc1 authored by Tejun Heo's avatar Tejun Heo Committed by Linus Torvalds
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6cdae741

lib/idr.c

+11 −9
Original line number Diff line number Diff line
@@ -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);