Re: [bugfix] SMP, shm-2.3.52-A0

From: Ingo Molnar (mingo@chiara.csoma.elte.hu)
Date: Fri Mar 17 2000 - 14:38:45 EST


On Fri, 17 Mar 2000, Andrew Morton wrote:

> > shm.c calls filp_open without the kernel lock held - this is illegal
> > because the dentry code is not yet SMP-threaded. The attached patch
> > (against pre3-2.3.52) fixes this.
>
> Prevent this from ever happening again....

actually, we do have something like this in the kernel, and it was added
some time ago, it's the 'BUG()' macro.

> + KASSERT(spin_is_locked(&kernel_flag));

this is more readable i believe:

        if (!spin_is_locked(&kernel_flag))
                BUG();

we have been adding such asserts since early 2.3. Btw., the dentry-assert
should be done in namei.c and dentry.c, not open.c, this is how i caught
the bug.

        Ingo

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