On Wed, Oct 31, 2012 at 05:35:46PM +0000, Christoph Lameter wrote: > 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.
Please refer to the comment in the patch above. But I think the patch is wrong anyway because it would introduce a warning, no? Thanks, -- Email: Herbert Xu <herb...@gondor.apana.org.au> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/