From 9bb26bc1ffa32ec983860a5a66b6f291a875e39d Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 27 Feb 2013 17:03:35 -0800 Subject: [PATCH] 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/idr.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/lib/idr.c b/lib/idr.c index ca5aa000d6c3..b8602e0b30da 100644 --- a/lib/idr.c +++ b/lib/idr.c @@ -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); -- 2.20.1