drbd: protect updates to integrits_tfm by tconn->data->mutex

Since we need to hold that mutex anyways to make sure the peer
gets that change in the right position in the data stream,
it makes a lot of sense to use the same mutex to ensure existence
of the tfm.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

2 files changed, 6 insertions, 5 deletions

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index e16722840767..c59012f96857 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -848,7 +848,7 @@ struct drbd_tconn {			/* is a resource from the config file */
         struct list_head out_of_sequence_requests;
 
         struct crypto_hash *cram_hmac_tfm;
-        struct crypto_hash *integrity_tfm;  /* checksums we compute */
+        struct crypto_hash *integrity_tfm;  /* checksums we compute, updates protected by tconn->data->mutex */
         struct crypto_hash *peer_integrity_tfm;  /* checksums we verify */
         struct crypto_hash *csums_tfm;
         struct crypto_hash *verify_tfm;
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 26d7763d5255..bca599a3c1e1 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -1720,11 +1720,11 @@ int drbd_send_dblock(struct drbd_conf *mdev, struct drbd_request *req)
         int dgs;
         int err;
 
+        sock = &mdev->tconn->data;
+        p = drbd_prepare_command(mdev, sock);
         dgs = (mdev->tconn->agreed_pro_version >= 87 && mdev->tconn->integrity_tfm) ?
                 crypto_hash_digestsize(mdev->tconn->integrity_tfm) : 0;
 
-        sock = &mdev->tconn->data;
-        p = drbd_prepare_command(mdev, sock);
         if (!p)
                 return -EIO;
         p->sector = cpu_to_be64(req->i.sector);
@@ -1793,11 +1793,12 @@ int drbd_send_block(struct drbd_conf *mdev, enum drbd_packet cmd,
         int err;
         int dgs;
 
+        sock = &mdev->tconn->data;
+        p = drbd_prepare_command(mdev, sock);
+
         dgs = (mdev->tconn->agreed_pro_version >= 87 && mdev->tconn->integrity_tfm) ?
                 crypto_hash_digestsize(mdev->tconn->integrity_tfm) : 0;
 
-        sock = &mdev->tconn->data;
-        p = drbd_prepare_command(mdev, sock);
         if (!p)
                 return -EIO;
         p->sector = cpu_to_be64(peer_req->i.sector);