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authorJoonsoo Kim <js1304@gmail.com>2013-04-29 15:07:27 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-04-29 15:54:33 -0700
commitef93247325028a35e089f3012c270379a89d052c (patch)
treed468969e31fe3a07a319c038771c220381a5cf4a /arch/x86
parent7136851117744f1d291bed6d307432699d405109 (diff)
downloadlinux-ef93247325028a35e089f3012c270379a89d052c.tar.gz
mm, vmalloc: change iterating a vmlist to find_vm_area()
This patchset removes vm_struct list management after initializing vmalloc. Adding and removing an entry to vmlist is linear time complexity, so it is inefficient. If we maintain this list, overall time complexity of adding and removing area to vmalloc space is O(N), although we use rbtree for finding vacant place and it's time complexity is just O(logN). And vmlist and vmlist_lock is used many places of outside of vmalloc.c. It is preferable that we hide this raw data structure and provide well-defined function for supporting them, because it makes that they cannot mistake when manipulating theses structure and it makes us easily maintain vmalloc layer. For kexec and makedumpfile, I export vmap_area_list, instead of vmlist. This comes from Atsushi's recommendation. For more information, please refer below link. https://lkml.org/lkml/2012/12/6/184 This patch: The purpose of iterating a vmlist is finding vm area with specific virtual address. find_vm_area() is provided for this purpose and more efficient, because it uses a rbtree. So change it. Signed-off-by: Joonsoo Kim <js1304@gmail.com> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Guan Xuetao <gxt@mprc.pku.edu.cn> Acked-by: Ingo Molnar <mingo@kernel.org> Acked-by: Chris Metcalf <cmetcalf@tilera.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp> Cc: Dave Anderson <anderson@redhat.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/mm/ioremap.c7
1 files changed, 1 insertions, 6 deletions
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 78fe3f1ac49..9a1e6583910 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -282,12 +282,7 @@ void iounmap(volatile void __iomem *addr)
in parallel. Reuse of the virtual address is prevented by
leaving it in the global lists until we're done with it.
cpa takes care of the direct mappings. */
- read_lock(&vmlist_lock);
- for (p = vmlist; p; p = p->next) {
- if (p->addr == (void __force *)addr)
- break;
- }
- read_unlock(&vmlist_lock);
+ p = find_vm_area((void __force *)addr);
if (!p) {
printk(KERN_ERR "iounmap: bad address %p\n", addr);