On Thu, 8 Feb 2007 16:20:12 +0300 Alexey Dobriyan <[EMAIL PROTECTED]> wrote:
> +again:
> spin_lock(&proc_subdir_lock);
> for (p = &parent->subdir; *p; p=&(*p)->next ) {
> if (!proc_match(len, fn, *p))
> continue;
> de = *p;
> +
> + /*
> + * Stop accepting new readers/writers. If you're dynamically
> + * allocating ->proc_fops, save a pointer somewhere.
> + */
> + spin_lock(&de->pde_unload_lock);
> + de->proc_fops = NULL;
> + /* Wait until all readers/writers are done. */
> + if (de->pde_users > 0) {
> + spin_unlock(&de->pde_unload_lock);
> + spin_unlock(&proc_subdir_lock);
> + schedule();
> + goto again;
> + }
> + spin_unlock(&de->pde_unload_lock);
aergh. This will devolve into busy-wait-until-we-expire-our-timeslice.
Would be nicer to do this with a wait_for_completion().
I guess it doesn't happen very often - if another process happens to
be in the middle or a read or write syscall to that /proc file.
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