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Commit bc9ae224 authored by Eric Dumazet's avatar Eric Dumazet Committed by Linus Torvalds
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radix-tree: must check __radix_tree_preload() return value 

__radix_tree_preload() only disables preemption if no error is returned.

So we really need to make sure callers always check the return value.

idr_preload() contract is to always disable preemption, so we need
to add a missing preempt_disable() if an error happened.

Similarly, ida_pre_get() only needs to call preempt_enable() in the
case no error happened.

Link: http://lkml.kernel.org/r/1504637190.15310.62.camel@edumazet-glaptop3.roam.corp.google.com


Fixes: 0a835c4f ("Reimplement IDR and IDA using the radix tree")
Fixes: 7ad3d4d8 ("ida: Move ida_bitmap to a percpu variable")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: <stable@vger.kernel.org>    [4.11+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7c61bd69

lib/radix-tree.c

+5 −4
Original line number Diff line number Diff line
@@ -463,7 +463,7 @@ radix_tree_node_free(struct radix_tree_node *node) 
 * To make use of this facility, the radix tree must be initialised without

 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().

 */

static int __radix_tree_preload(gfp_t gfp_mask, unsigned nr)

static __must_check int __radix_tree_preload(gfp_t gfp_mask, unsigned nr)

{

	struct radix_tree_preload *rtp;

	struct radix_tree_node *node;
@@ -2104,7 +2104,8 @@ EXPORT_SYMBOL(radix_tree_tagged); 
 */

void idr_preload(gfp_t gfp_mask)

{

	__radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE);

	if (__radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE))

		preempt_disable();

}

EXPORT_SYMBOL(idr_preload);
@@ -2118,12 +2119,12 @@ EXPORT_SYMBOL(idr_preload); 
 */

int ida_pre_get(struct ida *ida, gfp_t gfp)

{

	__radix_tree_preload(gfp, IDA_PRELOAD_SIZE);

	/*

	 * The IDA API has no preload_end() equivalent.  Instead,

	 * ida_get_new() can return -EAGAIN, prompting the caller

	 * to return to the ida_pre_get() step.

	 */

	if (!__radix_tree_preload(gfp, IDA_PRELOAD_SIZE))

		preempt_enable();



	if (!this_cpu_read(ida_bitmap)) {