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author | Joonsoo Kim <js1304@gmail.com> | 2013-04-29 15:07:32 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-04-29 15:54:34 -0700 |
commit | e81ce85f960c2e26efb5d0802d56c34533edb1bd (patch) | |
tree | 57e1d4ac1704a6311383403f8d11d51bbbd78961 /mm | |
parent | c69480adeea15883d9459a8adc3da3f6e8cb7a8c (diff) | |
download | linux-3.10-e81ce85f960c2e26efb5d0802d56c34533edb1bd.tar.gz linux-3.10-e81ce85f960c2e26efb5d0802d56c34533edb1bd.tar.bz2 linux-3.10-e81ce85f960c2e26efb5d0802d56c34533edb1bd.zip |
mm, vmalloc: iterate vmap_area_list, instead of vmlist in vread/vwrite()
Now, when we hold a vmap_area_lock, va->vm can't be discarded. So we can
safely access to va->vm when iterating a vmap_area_list with holding a
vmap_area_lock. With this property, change iterating vmlist codes in
vread/vwrite() to iterating vmap_area_list.
There is a little difference relate to lock, because vmlist_lock is mutex,
but, vmap_area_lock is spin_lock. It may introduce a spinning overhead
during vread/vwrite() is executing. But, these are debug-oriented
functions, so this overhead is not real problem for common case.
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.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: Chris Metcalf <cmetcalf@tilera.com>
Cc: Dave Anderson <anderson@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Ingo Molnar <mingo@kernel.org>
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 'mm')
-rw-r--r-- | mm/vmalloc.c | 48 |
1 files changed, 32 insertions, 16 deletions
diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 1bf94ad452b..59aa328007b 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2012,7 +2012,8 @@ static int aligned_vwrite(char *buf, char *addr, unsigned long count) long vread(char *buf, char *addr, unsigned long count) { - struct vm_struct *tmp; + struct vmap_area *va; + struct vm_struct *vm; char *vaddr, *buf_start = buf; unsigned long buflen = count; unsigned long n; @@ -2021,10 +2022,17 @@ long vread(char *buf, char *addr, unsigned long count) if ((unsigned long) addr + count < count) count = -(unsigned long) addr; - read_lock(&vmlist_lock); - for (tmp = vmlist; count && tmp; tmp = tmp->next) { - vaddr = (char *) tmp->addr; - if (addr >= vaddr + tmp->size - PAGE_SIZE) + spin_lock(&vmap_area_lock); + list_for_each_entry(va, &vmap_area_list, list) { + if (!count) + break; + + if (!(va->flags & VM_VM_AREA)) + continue; + + vm = va->vm; + vaddr = (char *) vm->addr; + if (addr >= vaddr + vm->size - PAGE_SIZE) continue; while (addr < vaddr) { if (count == 0) @@ -2034,10 +2042,10 @@ long vread(char *buf, char *addr, unsigned long count) addr++; count--; } - n = vaddr + tmp->size - PAGE_SIZE - addr; + n = vaddr + vm->size - PAGE_SIZE - addr; if (n > count) n = count; - if (!(tmp->flags & VM_IOREMAP)) + if (!(vm->flags & VM_IOREMAP)) aligned_vread(buf, addr, n); else /* IOREMAP area is treated as memory hole */ memset(buf, 0, n); @@ -2046,7 +2054,7 @@ long vread(char *buf, char *addr, unsigned long count) count -= n; } finished: - read_unlock(&vmlist_lock); + spin_unlock(&vmap_area_lock); if (buf == buf_start) return 0; @@ -2085,7 +2093,8 @@ finished: long vwrite(char *buf, char *addr, unsigned long count) { - struct vm_struct *tmp; + struct vmap_area *va; + struct vm_struct *vm; char *vaddr; unsigned long n, buflen; int copied = 0; @@ -2095,10 +2104,17 @@ long vwrite(char *buf, char *addr, unsigned long count) count = -(unsigned long) addr; buflen = count; - read_lock(&vmlist_lock); - for (tmp = vmlist; count && tmp; tmp = tmp->next) { - vaddr = (char *) tmp->addr; - if (addr >= vaddr + tmp->size - PAGE_SIZE) + spin_lock(&vmap_area_lock); + list_for_each_entry(va, &vmap_area_list, list) { + if (!count) + break; + + if (!(va->flags & VM_VM_AREA)) + continue; + + vm = va->vm; + vaddr = (char *) vm->addr; + if (addr >= vaddr + vm->size - PAGE_SIZE) continue; while (addr < vaddr) { if (count == 0) @@ -2107,10 +2123,10 @@ long vwrite(char *buf, char *addr, unsigned long count) addr++; count--; } - n = vaddr + tmp->size - PAGE_SIZE - addr; + n = vaddr + vm->size - PAGE_SIZE - addr; if (n > count) n = count; - if (!(tmp->flags & VM_IOREMAP)) { + if (!(vm->flags & VM_IOREMAP)) { aligned_vwrite(buf, addr, n); copied++; } @@ -2119,7 +2135,7 @@ long vwrite(char *buf, char *addr, unsigned long count) count -= n; } finished: - read_unlock(&vmlist_lock); + spin_unlock(&vmap_area_lock); if (!copied) return 0; return buflen; |