On Wed, 31 Oct 2012, Shan Wei wrote:
> -
> list_for_each_entry(pos, &ipcomp_tfms_list, list) {
> struct crypto_comp *tfm;
>
> tfms = pos->tfms;
> - tfm = *per_cpu_ptr(tfms, cpu);
> +
> + /* This can be any valid CPU ID so we don't need locking. */
> + tfm = *this_cpu_ptr(tfms);
It would be better to use
this_cpu_read(tfms)
since that would also make it atomic vs interrupts. The above code (both
original and modified) could determine a pointer to a per cpu structure
and then take an interrupt which would move the task. On return we would
be accessing the per cpu variable of another processor.
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