linux-kernel - [PATCH v2 4/4] crypto/pcrypt: Do not use isolated CPUs for callback

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Date:   Thu, 13 Oct 2022 15:40:29 -0300
From:   Leonardo Bras <leobras@...hat.com>
To:     Steffen Klassert <steffen.klassert@...unet.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Valentin Schneider <vschneid@...hat.com>,
        Tejun Heo <tj@...nel.org>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Leonardo Bras <leobras@...hat.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Phil Auld <pauld@...hat.com>,
        Antoine Tenart <atenart@...nel.org>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Wang Yufen <wangyufen@...wei.com>, mtosatti@...hat.com
Cc:     linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH v2 4/4] crypto/pcrypt: Do not use isolated CPUs for callback

Currently pcrypt_aead_init_tfm() will pick callback cpus (ctx->cb_cpu)
from any online cpus. Later padata_reorder() will queue_work_on() the
chosen cb_cpu.

This is undesired if the chosen cb_cpu is listed as isolated (i.e. using
isolcpus=... or nohz_full=... kernel parameters), since the work queued
will interfere with the workload on the isolated cpu.

Make sure isolated cpus are not used for pcrypt.

Signed-off-by: Leonardo Bras <leobras@...hat.com>
---
 crypto/pcrypt.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/crypto/pcrypt.c b/crypto/pcrypt.c
index 9d10b846ccf73..0162629a03957 100644
--- a/crypto/pcrypt.c
+++ b/crypto/pcrypt.c
@@ -16,6 +16,7 @@
 #include <linux/kobject.h>
 #include <linux/cpu.h>
 #include <crypto/pcrypt.h>
+#include <linux/sched/isolation.h>
 
 static struct padata_instance *pencrypt;
 static struct padata_instance *pdecrypt;
@@ -175,13 +176,15 @@ static int pcrypt_aead_init_tfm(struct crypto_aead *tfm)
 	struct pcrypt_instance_ctx *ictx = aead_instance_ctx(inst);
 	struct pcrypt_aead_ctx *ctx = crypto_aead_ctx(tfm);
 	struct crypto_aead *cipher;
+	const cpumask_t *hk_wq = housekeeping_cpumask(HK_TYPE_WQ);
 
 	cpu_index = (unsigned int)atomic_inc_return(&ictx->tfm_count) %
-		    cpumask_weight(cpu_online_mask);
+		    cpumask_weight_and(hk_wq, cpu_online_mask);
 
-	ctx->cb_cpu = cpumask_first(cpu_online_mask);
+	ctx->cb_cpu = cpumask_first_and(hk_wq, cpu_online_mask);
 	for (cpu = 0; cpu < cpu_index; cpu++)
-		ctx->cb_cpu = cpumask_next(ctx->cb_cpu, cpu_online_mask);
+		ctx->cb_cpu = cpumask_next_and(ctx->cb_cpu, hk_wq,
+					       cpu_online_mask);
 
 	cipher = crypto_spawn_aead(&ictx->spawn);
 
-- 
2.38.0