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    SubjectRe: Since sysfs_mount is static and used only in sysfs_init function, it could be just an automatic variable.
    On Sun, Dec 02, 2007 at 02:52:17PM +0800, rae l wrote:
    > On Dec 2, 2007 12:48 PM, Greg KH <> wrote:
    > ...
    > > > and where is a detailed explaination on kern_mount? could someone give
    > > > some comments or documentation pointers on this?
    > >
    > > See the patches that Eric Biederman just posted to lkml for why this
    > > structure is a static pointer this way right now, it's in preparation
    > > for future patches.
    > I have checked commit 7d0c7d676cc066413e1583b5af9fba8011972d41 by Eric
    > W. Biederman,
    > which just make sysfs_mount from externally visible to static that
    > could be only used in one c file,
    > but I mean that the static variable is still on kernel bss section,
    > this consumes a pointer (4 or 8 bytes) memory,
    > through a grep from fs/sysfs/, it appears that the variable
    > sysfs_mount is only used in the sysfs_init function,
    > $ grep -RsInw sysfs_mount fs/sysfs/
    > fs/sysfs/mount.c:25:static struct vfsmount *sysfs_mount;
    > fs/sysfs/mount.c:101: sysfs_mount = kern_mount(&sysfs_fs_type);
    > fs/sysfs/mount.c:102: if (IS_ERR(sysfs_mount)) {
    > fs/sysfs/mount.c:104: err = PTR_ERR(sysfs_mount);
    > fs/sysfs/mount.c:105: sysfs_mount = NULL;
    > we could mark this variable an automatic one, which scope is just in
    > this function, thus created and destroyed with the stack,
    > this approach does not consume a pointer on kernel bss section,
    > Why not do this?

    Again, see the patches he _just_ posted to lkml, the specific message
    you are looking for is:
    Message-ID: <>
    Subject: [PATCH 01/10] sysfs: Make sysfs_mount static again.

    Also see the whole long thread for more details.

    If you have further questions about this, please ask Eric.


    greg k-h

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      Last update: 2007-12-02 08:53    [W:0.022 / U:54.168 seconds]
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