Messages in this thread Patch in this message | | | Date | Tue, 15 Sep 2009 12:09:39 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [PATCH 0/3] /proc/kmem cleanups and hwpoison bits |
| |
On Tue, 15 Sep 2009 10:18:51 +0800 Wu Fengguang <fengguang.wu@intel.com> wrote:
> Hi Kame, > > Here are 3 more kmem patches in my queue. Comments are welcome. > If you feel good about them, I can send all recent kmem cleanup > patches for you. >
This is my quick hack. But I don't want to be an obstacle for you. So, I'll wait for your updates.
== Now, /dev/kmem's read/write vmalloc area doesn't do range-check. Because vread/vwrite traverse vmalloc area list under system-wide spinlock, it's better to avoid unnecessary to do unnecessary calls to vread/vwrite.
And, vread/vwrite returns 0 if we accessed memory holes. We can avoid copy-to-user in read side, we just ignore at write.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> --- drivers/char/mem.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-)
Index: linux-2.6.31/drivers/char/mem.c =================================================================== --- linux-2.6.31.orig/drivers/char/mem.c +++ linux-2.6.31/drivers/char/mem.c @@ -437,17 +437,19 @@ static ssize_t read_kmem(struct file *fi } if (count > 0) { - kbuf = (char *)__get_free_page(GFP_KERNEL); + kbuf = (char *)__get_free_page(GFP_KERNEL | __GFP_ZERO); if (!kbuf) return -ENOMEM; while (count > 0) { sz = size_inside_page(p, count); - sz = vread(kbuf, (char *)p, sz); - if (!sz) - break; - if (copy_to_user(buf, kbuf, sz)) { - free_page((unsigned long)kbuf); - return -EFAULT; + if (is_vmalloc_or_module_addr((void*)p)) { + /* returns Non-zero if a page is found */ + if (vread(kbuf, (char *)p, sz)) + if (copy_to_user(buf, kbuf, sz)) { + free_page((unsigned long)kbuf); + return -EFAULT; + } + } } count -= sz; buf += sz; @@ -541,6 +543,11 @@ static ssize_t write_kmem(struct file * unsigned long sz = size_inside_page(p, count); unsigned long n; + if (is_vmalloc_or_module_addr((void*)p)) { + free_page((unsignedl long)kbuf); + retrun -EFAULT; + } + n = copy_from_user(kbuf, buf, sz); if (n) { if (wrote + virtr) @@ -548,7 +555,11 @@ static ssize_t write_kmem(struct file * free_page((unsigned long)kbuf); return -EFAULT; } - sz = vwrite(kbuf, (char *)p, sz); + /* + * returns non-zero if copied successfully.... + * But we don't care it. just make a progress. + */ + vwrite(kbuf, (char *)p, sz); count -= sz; buf += sz; virtr += sz;
| |