DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 5D20B606A31C
Date: Wed, 11 Nov 2026 18:44:50 +0800
From: Herbert Xu <herbert@gondor.apana.org.au>
To: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Cc: Kristen Accardi <kristen.c.accardi@intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/4] crypto: iaa - use RCU per-package WQ tables
Message-ID: <avRHIuISSNUxfAU4@gondor.apana.org.au>
References: <20261019-iaa-crypto-wq-tables-v1-0-fab67b2a1538@intel.com>
 <20261019-iaa-crypto-wq-tables-v1-3-fab67b2a1538@intel.com>
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In-Reply-To: <20261019-iaa-crypto-wq-tables-v1-3-fab67b2a1538@intel.com>

On Mon, Oct 19, 2026 at 04:06:22PM -0700, Vinicius Costa Gomes wrote:
> rebalance_wq_table() gives CPU n all the WQs of IAA device
> n / cpus_per_iaa. The flat index ignores package boundaries, so a CPU
> can be paired with a device on another package, and each CPU sends all
> its requests to one device while the other devices of its package stay
> idle. The table is also rebuilt in place, so a request issued during a
> probe or remove can read a NULL WQ and fail with -ENODEV.
> 
> Replace it with one table per package, holding the WQs of every IAA
> device on that package, and have each CPU round-robin over its package's
> table. Rebalance builds the whole set of tables and publishes it with
> rcu_replace_pointer(). The submit paths look the WQ up, and take their
> reference on it, inside an RCU read-side section.
> 
> - A package without IAA devices gets a copy of another package's table,
>   so the lookup needs no fallback.
> - Every table has room for all the WQs, a few pointers more than it
>   needs, so they can be sized without counting per package.
> - If a rebalance fails, the current tables are kept. On removal they
>   are cleared instead, because they still hold the removed WQ. Removal
>   then waits for a grace period before returning, because the idxd_wq
>   can be freed after that.
> 
> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
> ---
>  drivers/crypto/intel/iaa/iaa_crypto.h      |   7 -
>  drivers/crypto/intel/iaa/iaa_crypto_main.c | 346 ++++++++++-------------------
>  2 files changed, 117 insertions(+), 236 deletions(-)

Please respond to this comment:

https://sashiko.dev/#/patchset/20261019-iaa-crypto-wq-tables-v1-0-fab67b2a1538%40intel.com

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt