crypto: cryptd - Use nested-BH locking for cryptd_cpu_queue

cryptd_queue::cryptd_cpu_queue is a per-CPU variable and relies on
disabled BH for its locking. Without per-CPU locking in
local_bh_disable() on PREEMPT_RT this data structure requires explicit
locking.

Add a local_lock_t to the struct cryptd_cpu_queue and use
local_lock_nested_bh() for locking. This change adds only lockdep
coverage and does not alter the functional behaviour for !PREEMPT_RT.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: linux-crypto@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/cryptd.c b/crypto/cryptd.c
index 5bb6f8d88cc2ec93a0caa8e452f9c9313b022b41..efff54e707cb580d915174c866066be9000923ea 100644 (file)
--- a/crypto/cryptd.c
+++ b/crypto/cryptd.c
@@ -34,6 +34,7 @@ MODULE_PARM_DESC(cryptd_max_cpu_qlen, "Set cryptd Max queue depth");
 static struct workqueue_struct *cryptd_wq;
 
 struct cryptd_cpu_queue {
+       local_lock_t bh_lock;
        struct crypto_queue queue;
        struct work_struct work;
 };
@@ -110,6 +111,7 @@ 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);
+               local_lock_init(&cpu_queue->bh_lock);
        }
        pr_info("cryptd: max_cpu_qlen set to %d\n", max_cpu_qlen);
        return 0;
@@ -135,6 +137,7 @@ static int cryptd_enqueue_request(struct cryptd_queue *queue,
        refcount_t *refcnt;
 
        local_bh_disable();
+       local_lock_nested_bh(&queue->cpu_queue->bh_lock);
        cpu_queue = this_cpu_ptr(queue->cpu_queue);
        err = crypto_enqueue_request(&cpu_queue->queue, request);
 
@@ -151,6 +154,7 @@ static int cryptd_enqueue_request(struct cryptd_queue *queue,
        refcount_inc(refcnt);
 
 out:
+       local_unlock_nested_bh(&queue->cpu_queue->bh_lock);
        local_bh_enable();
 
        return err;
@@ -169,8 +173,10 @@ static void cryptd_queue_worker(struct work_struct *work)
         * Only handle one request at a time to avoid hogging crypto workqueue.
         */
        local_bh_disable();
+       __local_lock_nested_bh(&cpu_queue->bh_lock);
        backlog = crypto_get_backlog(&cpu_queue->queue);
        req = crypto_dequeue_request(&cpu_queue->queue);
+       __local_unlock_nested_bh(&cpu_queue->bh_lock);
        local_bh_enable();
 
        if (!req)