On Thu, Mar 9, 2017 at 4:39 AM, Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote: > On Wed, Mar 08, 2017 at 12:38:40PM -0500, Dan Streetman wrote: >> >> It looks like the crypto_scomp interface is buried under >> include/crypto/internal/scompress.h, however that's exactly what zswap >> should be using. We don't need to switch to an asynchronous interface >> that's rather significantly more complicated, and then use it in a >> synchronous way. The crypto_scomp interface should probably be made >> public, not an implementation internal. > > No scomp is not meant to be used externally. We provide exactly > one compression interface and it's acomp. acomp can be used > synchronously by setting the CRYPTO_ALG_ASYNC bit in the mask > field when allocating the algorithm. setting the ASYNC bit makes it synchronous? that seems backwards...? Anyway, I have a few concerns about moving over to using that first, specifically: - no docs on acomp in Documentation/crypto/ that I can see - no place in the crypto code that I can see that parses ALG_ASYNC to make the crypto_acomp_compress() call synchronous - no synchronous test in crypto/testmgr.c Maybe I'm reading the code wrong, but it looks like any compression backend that is actually scomp, actually does the (de)compression synchronously. In crypto_acomp_init_tfm(), if the tfm is not crypto_acomp_type (and I assume because all the current implementations register as scomp, they aren't acomp_type) it calls crypto_init_scomp_ops_async(), which then sets ->compress to scomp_acomp_compress() and that function appears to directly call the scomp compression function. This is just after a very quick look, so maybe I'm reading it wrong. I'll look some more, and also add a synchronous testmgr test so i can understand how it works better. Is the acomp interface fully ready for use? > > The existing compression interface will be phased out. > > Cheers, > -- > Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> > Home Page: http://gondor.apana.org.au/~herbert/ > PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
