From d2514ef81a05c6ee7103490b7c722b1dc4f30add Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Thu, 26 Jul 2018 18:52:00 +0200 Subject: [PATCH 096/158] crypto: cryptd - add a lock instead preempt_disable/local_bh_disable cryptd has a per-CPU lock which protected with local_bh_disable() and preempt_disable(). Add an explicit spin_lock to make the locking context more obvious and visible to lockdep. Since it is a per-CPU lock, there should be no lock contention on the actual spinlock. There is a small race-window where we could be migrated to another CPU after the cpu_queue has been obtain. This is not a problem because the actual ressource is protected by the spinlock. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner --- crypto/cryptd.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) Index: linux-5.15.19-rt29/crypto/cryptd.c =================================================================== --- linux-5.15.19-rt29.orig/crypto/cryptd.c +++ linux-5.15.19-rt29/crypto/cryptd.c @@ -36,6 +36,7 @@ static struct workqueue_struct *cryptd_w struct cryptd_cpu_queue { struct crypto_queue queue; struct work_struct work; + spinlock_t qlock; }; struct cryptd_queue { @@ -105,6 +106,7 @@ static int cryptd_init_queue(struct cryp cpu_queue = per_cpu_ptr(queue->cpu_queue, cpu); crypto_init_queue(&cpu_queue->queue, max_cpu_qlen); INIT_WORK(&cpu_queue->work, cryptd_queue_worker); + spin_lock_init(&cpu_queue->qlock); } pr_info("cryptd: max_cpu_qlen set to %d\n", max_cpu_qlen); return 0; @@ -129,8 +131,10 @@ static int cryptd_enqueue_request(struct struct cryptd_cpu_queue *cpu_queue; refcount_t *refcnt; - cpu = get_cpu(); - cpu_queue = this_cpu_ptr(queue->cpu_queue); + cpu_queue = raw_cpu_ptr(queue->cpu_queue); + spin_lock_bh(&cpu_queue->qlock); + cpu = smp_processor_id(); + err = crypto_enqueue_request(&cpu_queue->queue, request); refcnt = crypto_tfm_ctx(request->tfm); @@ -146,7 +150,7 @@ static int cryptd_enqueue_request(struct refcount_inc(refcnt); out_put_cpu: - put_cpu(); + spin_unlock_bh(&cpu_queue->qlock); return err; } @@ -162,16 +166,11 @@ static void cryptd_queue_worker(struct w cpu_queue = container_of(work, struct cryptd_cpu_queue, work); /* * Only handle one request at a time to avoid hogging crypto workqueue. - * preempt_disable/enable is used to prevent being preempted by - * cryptd_enqueue_request(). local_bh_disable/enable is used to prevent - * cryptd_enqueue_request() being accessed from software interrupts. */ - local_bh_disable(); - preempt_disable(); + spin_lock_bh(&cpu_queue->qlock); backlog = crypto_get_backlog(&cpu_queue->queue); req = crypto_dequeue_request(&cpu_queue->queue); - preempt_enable(); - local_bh_enable(); + spin_unlock_bh(&cpu_queue->qlock); if (!req) return;