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    SubjectRe: [PATCH 3/6] i386 virtualization - Make ldt a desc struct
    Chuck Ebbert wrote:

    >
    >>@@ -97,14 +96,16 @@
    >>
    >> void destroy_ldt(struct mm_struct *mm)
    >> {
    >>+ int pages = mm->context.ldt_pages;
    >>+
    >> if (mm == current->active_mm)
    >> clear_LDT();
    >>- ClearPagesLDT(mm->context.ldt, (mm->context.size * LDT_ENTRY_SIZE) / PAGE_SIZE);
    >>- if (mm->context.size*LDT_ENTRY_SIZE > PAGE_SIZE)
    >>+ ClearPagesLDT(mm->context.ldt, pages);
    >>+ if (pages > 1)
    >> vfree(mm->context.ldt);
    >> else
    >> kfree(mm->context.ldt);
    >>- mm->context.size = 0;
    >>+ mm->context.ldt_pages = 0; <====================
    >> }
    >>
    >> static int read_ldt(void __user * ptr, unsigned long bytecount)
    >>
    >>
    >
    > destroy_ldt does not zero "ldt", just the size. Potential bug?
    >
    >

    Not a bug, truly unnecessary at all.

    Several reviewers noticed that initialization and destruction of the
    mm->context is unnecessary, since the entire MM struct is zeroed on
    allocation anyways.

    Verified with BUG_ON(mm->context.ldt || mm->context.ldt_pages);

    Signed-off-by: Zachary Amsden <zach@vmware.com>
    Index: linux-2.6.13/include/asm-i386/mmu_context.h
    ===================================================================
    --- linux-2.6.13.orig/include/asm-i386/mmu_context.h 2005-08-15 11:23:32.000000000 -0700
    +++ linux-2.6.13/include/asm-i386/mmu_context.h 2005-08-16 11:35:11.000000000 -0700
    @@ -16,7 +16,6 @@
    struct mm_struct * old_mm;
    int retval = 0;

    - memset(&mm->context, 0, sizeof(mm->context));
    init_MUTEX(&mm->context.sem);
    old_mm = current->mm;
    if (old_mm && unlikely(old_mm->context.ldt)) {
    Index: linux-2.6.13/arch/i386/kernel/ldt.c
    ===================================================================
    --- linux-2.6.13.orig/arch/i386/kernel/ldt.c 2005-08-15 11:23:32.000000000 -0700
    +++ linux-2.6.13/arch/i386/kernel/ldt.c 2005-08-16 11:12:59.000000000 -0700
    @@ -105,7 +105,6 @@
    vfree(mm->context.ldt);
    else
    kfree(mm->context.ldt);
    - mm->context.ldt_pages = 0;
    }

    static int read_ldt(void __user * ptr, unsigned long bytecount)
    \
     
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      Last update: 2005-08-16 20:47    [W:0.033 / U:5.440 seconds]
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