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authorTejun Heo <tj@kernel.org>2009-11-11 07:35:18 +0100
committerTejun Heo <tj@kernel.org>2009-11-12 16:55:35 +0100
commit833af8427be4b217b5bc522f61afdbd3f1d282c2 (patch)
tree7af86f8c599c4513f81c9b37ec34926cb4728316 /Documentation/printk-formats.txt
parentsched: move rq_weight data array out of .percpu (diff)
downloadlinux-833af8427be4b217b5bc522f61afdbd3f1d282c2.tar.xz
linux-833af8427be4b217b5bc522f61afdbd3f1d282c2.zip
percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability
pcpu_extend_area_map() had the following two bugs. * It should return 1 if pcpu_lock was dropped and reacquired but it returned 0. This could lead to oops if free_percpu() races with area map extension. * pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might end up calling vfree() which isn't IRQ safe. This could lead to deadlock through lock order inversion via IRQ. In addition, Linus pointed out that the temporary lock dropping and subtle three-way return value of pcpu_extend_area_map() was very ugly and suggested to split the function into two - pcpu_need_to_extend() and pcpu_extend_area_map(). This patch restructures pcpu_extend_area_map() as suggested and fixes the two bugs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu>
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