crypto: virtio - Convert from tasklet to BH workqueue

The only generic interface to execute asynchronously in the BH context
is tasklet; however, it's marked deprecated and has some design flaws
such as the execution code accessing the tasklet item after the
execution is complete which can lead to subtle use-after-free in certain
usage scenarios and less-developed flush and cancel mechanisms.

To replace tasklets, BH workqueue support was recently added. A BH
workqueue behaves similarly to regular workqueues except that the queued
work items are executed in the BH context.

Convert virtio_crypto_core.c from tasklet to BH workqueue.

Semantically, this is an equivalent conversion and there shouldn't be
any user-visible behavior changes. The BH workqueue implementation uses
the same softirq infrastructure, and performance-critical networking
conversions have shown no measurable performance impact.

Signed-off-by: Pat Somaru <patso@likewhatevs.io>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/crypto/virtio/virtio_crypto_common.h b/drivers/crypto/virtio/virtio_crypto_common.h
index e559bdadf4f9132544fec24775191a7da0bed70d..0c2efdc8325785ea3edb36b2326d0225592c0d76 100644 (file)
--- a/drivers/crypto/virtio/virtio_crypto_common.h
+++ b/drivers/crypto/virtio/virtio_crypto_common.h
@@ -11,6 +11,7 @@
 #include <linux/crypto.h>
 #include <linux/spinlock.h>
 #include <linux/interrupt.h>
+#include <linux/workqueue.h>
 #include <crypto/aead.h>
 #include <crypto/aes.h>
 #include <crypto/engine.h>
@@ -29,7 +30,7 @@ struct data_queue {
        char name[32];
 
        struct crypto_engine *engine;
-       struct tasklet_struct done_task;
+       struct work_struct done_work;
 };
 
 struct virtio_crypto {

diff --git a/drivers/crypto/virtio/virtio_crypto_core.c b/drivers/crypto/virtio/virtio_crypto_core.c
index 955bff8820dab2db354341435a712ea82f63c2a2..ee83bf6568f049c57b6ead333e1181980a12e4d7 100644 (file)
--- a/drivers/crypto/virtio/virtio_crypto_core.c
+++ b/drivers/crypto/virtio/virtio_crypto_core.c
@@ -70,9 +70,9 @@ int virtio_crypto_ctrl_vq_request(struct virtio_crypto *vcrypto, struct scatterl
        return 0;
 }
 
-static void virtcrypto_done_task(unsigned long data)
+static void virtcrypto_done_work(struct work_struct *work)
 {
-       struct data_queue *data_vq = (struct data_queue *)data;
+       struct data_queue *data_vq = from_work(data_vq, work, done_work);
        struct virtqueue *vq = data_vq->vq;
        struct virtio_crypto_request *vc_req;
        unsigned long flags;
@@ -96,7 +96,7 @@ static void virtcrypto_dataq_callback(struct virtqueue *vq)
        struct virtio_crypto *vcrypto = vq->vdev->priv;
        struct data_queue *dq = &vcrypto->data_vq[vq->index];
 
-       tasklet_schedule(&dq->done_task);
+       queue_work(system_bh_wq, &dq->done_work);
 }
 
 static int virtcrypto_find_vqs(struct virtio_crypto *vi)
@@ -150,8 +150,7 @@ static int virtcrypto_find_vqs(struct virtio_crypto *vi)
                        ret = -ENOMEM;
                        goto err_engine;
                }
-               tasklet_init(&vi->data_vq[i].done_task, virtcrypto_done_task,
-                               (unsigned long)&vi->data_vq[i]);
+               INIT_WORK(&vi->data_vq[i].done_work, virtcrypto_done_work);
        }
 
        kfree(vqs_info);
@@ -501,7 +500,7 @@ static void virtcrypto_remove(struct virtio_device *vdev)
        if (virtcrypto_dev_started(vcrypto))
                virtcrypto_dev_stop(vcrypto);
        for (i = 0; i < vcrypto->max_data_queues; i++)
-               tasklet_kill(&vcrypto->data_vq[i].done_task);
+               cancel_work_sync(&vcrypto->data_vq[i].done_work);
        virtio_reset_device(vdev);
        virtcrypto_free_unused_reqs(vcrypto);
        virtcrypto_clear_crypto_engines(vcrypto);