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crypto: cryptd - add a lock instead preempt_disable/local_bh_disable

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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 <bigeasy@linutronix.de>
This commit is contained in:
Sebastian Andrzej Siewior
2018-07-26 18:52:00 +02:00
committed by jianlong.wang
parent 1e81915fd1
commit e42fa6fbec
1 changed files with 9 additions and 10 deletions
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19
crypto/cryptd.c
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@@ -39,6 +39,7 @@ MODULE_PARM_DESC(cryptd_max_cpu_qlen, "Set cryptd Max queue depth");
struct cryptd_cpu_queue {
struct crypto_queue queue;
struct work_struct work;
spinlock_t qlock;
};
struct cryptd_queue {
@@ -117,6 +118,7 @@ static int cryptd_init_queue(struct cryptd_queue *queue,
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;
@@ -141,8 +143,10 @@ static int cryptd_enqueue_request(struct cryptd_queue *queue,
struct cryptd_cpu_queue *cpu_queue;
atomic_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);
@@ -158,7 +162,7 @@ static int cryptd_enqueue_request(struct cryptd_queue *queue,
atomic_inc(refcnt);
out_put_cpu:
put_cpu();
spin_unlock_bh(&cpu_queue->qlock);
return err;
}
@@ -174,16 +178,11 @@ static void cryptd_queue_worker(struct work_struct *work)
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;