On Wed, Aug 25, 2021 at 1:08 AM Herbert Xu herbert@gondor.apana.org.au wrote:
On Tue, Aug 24, 2021 at 04:34:58PM -0700, Eric Dumazet wrote:
On 8/24/21 2:34 PM, Leonard Crestez wrote:
The crypto_shash API is used in order to compute packet signatures. The API comes with several unfortunate limitations:
- Allocating a crypto_shash can sleep and must be done in user context.
- Packet signatures must be computed in softirq context
- Packet signatures use dynamic "traffic keys" which require exclusive
access to crypto_shash for crypto_setkey.
The solution is to allocate one crypto_shash for each possible cpu for each algorithm at setsockopt time. The per-cpu tfm is then borrowed from softirq context, signatures are computed and the tfm is returned.
I could not see the per-cpu stuff that you mention in the changelog.
Perhaps it's time we moved the key information from the tfm into the request structure for hashes? Or at least provide a way for the key to be in the request structure in addition to the tfm as the tfm model still works for IPsec. Ard/Eric, what do you think about that?
What is the typical size of a ' tfm' and associated data ?
per-cpu tfm might still make sense, if we had proper NUMA affinities. AFAIK, currently we can not provide a numa node to crypto allocations.
So using construct like this ends up allocating all data on one single NUMA node
for_each_possible_cpu(cpu) { tfm = crypto_alloc_shash(algo->name, 0, 0); if (IS_ERR(tfm)) return PTR_ERR(tfm); p_tfm = per_cpu_ptr(algo->tfms, cpu); *p_tfm = tfm; }