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    SubjectRe: [RFC][PATCH] kmemdup_from_user(): introduce
    On Fri, Mar 06, 2009 at 04:27:53PM +0800, Li Zefan wrote:
    > Alexey Dobriyan wrote:
    > > On Fri, Mar 06, 2009 at 03:04:12PM +0800, Li Zefan wrote:
    > >> I notice there are many places doing copy_from_user() which follows
    > >> kmalloc():
    > >>
    > >> dst = kmalloc(len, GFP_KERNEL);
    > >> if (!dst)
    > >> return -ENOMEM;
    > >> if (copy_from_user(dst, src, len)) {
    > >> kfree(dst);
    > >> return -EFAULT
    > >> }
    > >>
    > >> kmemdup_from_user() is a wrapper of the above code. With this new
    > >> function, we don't have to write 'len' twice, which can lead to
    > >> typos/mistakes. It also produces smaller code.
    > >
    > > Name totally sucks, it mixes kernel idiom of allocation with purely
    > > userspace function.
    > >
    >
    > I'm not good at English, and I don't know why "kernel memory duplicated
    > from user space" is so bad...
    >
    > or memdup_user() ?
    >
    > >> A qucik grep shows 250+ places where kmemdup_from_user() *may* be
    > >> used. I'll prepare a patchset to do this conversion.
    > >
    > > 250?
    > >
    >
    > I just found out how many copy_from_user() following km/zalloc(), so
    > not all of them are replace-able.
    >
    > > Let's not add wrapper for every two lines that happen to be used
    > > together.
    > >
    >
    > Why not if we have good reasons? And I don't think we can call this
    > "happen to" if there are 250+ of them?

    Please, read through them. This "250+" number suddenly will become
    like 20, because wrapper is not good enough.


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