drbd: Basic refcounting for drbd_tconn

References hold by:
 * Each (running) drbd thread has a reference on tconn
 * Each mdev has a referenc on tconn
 * Beeing in the all_tconn list counts for one reference
 * Each after_conn_state_chg_work has a reference to tconn

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

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 0fb3fc3..3abf982 100644 (file)
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -828,6 +828,7 @@ enum {
 struct drbd_tconn {                    /* is a resource from the config file */
        char *name;                     /* Resource name */
        struct list_head all_tconn;     /* linked on global drbd_tconns */
+       struct kref kref;
        struct idr volumes;             /* <tconn, vnr> to mdev mapping */
        enum drbd_conns cstate;         /* Only C_STANDALONE to C_WF_REPORT_PARAMS */
        unsigned susp:1;                /* IO suspended by user */
@@ -1378,8 +1379,8 @@ extern int conn_lowest_minor(struct drbd_tconn *tconn);
 enum drbd_ret_code conn_new_minor(struct drbd_tconn *tconn, unsigned int minor, int vnr);
 extern void drbd_delete_device(struct drbd_conf *mdev);
 
-struct drbd_tconn *drbd_new_tconn(const char *name);
-extern void drbd_free_tconn(struct drbd_tconn *tconn);
+struct drbd_tconn *conn_create(const char *name);
+extern void conn_destroy(struct kref *kref);
 struct drbd_tconn *conn_by_name(const char *name);
 extern void conn_free_crypto(struct drbd_tconn *tconn);
 

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index b9c103f..11427f5 100644 (file)
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -509,6 +509,8 @@ restart:
        conn_info(tconn, "Terminating %s\n", current->comm);
 
        /* Release mod reference taken when thread was started */
+
+       kref_put(&tconn->kref, &conn_destroy);
        module_put(THIS_MODULE);
        return retval;
 }
@@ -546,6 +548,8 @@ int drbd_thread_start(struct drbd_thread *thi)
                        return false;
                }
 
+               kref_get(&thi->tconn->kref);
+
                init_completion(&thi->stop);
                thi->reset_cpu_mask = 1;
                thi->t_state = RUNNING;
@@ -558,6 +562,7 @@ int drbd_thread_start(struct drbd_thread *thi)
                if (IS_ERR(nt)) {
                        conn_err(tconn, "Couldn't start thread\n");
 
+                       kref_put(&tconn->kref, &conn_destroy);
                        module_put(THIS_MODULE);
                        return false;
                }
@@ -2237,6 +2242,8 @@ static void drbd_release_all_peer_reqs(struct drbd_conf *mdev)
 /* caution. no locking. */
 void drbd_delete_device(struct drbd_conf *mdev)
 {
+       struct drbd_tconn *tconn = mdev->tconn;
+
        idr_remove(&mdev->tconn->volumes, mdev->vnr);
        idr_remove(&minors, mdev_to_minor(mdev));
        synchronize_rcu();
@@ -2272,6 +2279,8 @@ void drbd_delete_device(struct drbd_conf *mdev)
        put_disk(mdev->vdisk);
        blk_cleanup_queue(mdev->rq_queue);
        kfree(mdev);
+
+       kref_put(&tconn->kref, &conn_destroy);
 }
 
 static void drbd_cleanup(void)
@@ -2409,7 +2418,7 @@ void conn_free_crypto(struct drbd_tconn *tconn)
        tconn->int_dig_vv = NULL;
 }
 
-struct drbd_tconn *drbd_new_tconn(const char *name)
+struct drbd_tconn *conn_create(const char *name)
 {
        struct drbd_tconn *tconn;
 
@@ -2455,6 +2464,7 @@ struct drbd_tconn *drbd_new_tconn(const char *name)
        };
 
        down_write(&drbd_cfg_rwsem);
+       kref_init(&tconn->kref);
        list_add_tail(&tconn->all_tconn, &drbd_tconns);
        up_write(&drbd_cfg_rwsem);
 
@@ -2471,9 +2481,10 @@ fail:
        return NULL;
 }
 
-void drbd_free_tconn(struct drbd_tconn *tconn)
+void conn_destroy(struct kref *kref)
 {
-       list_del(&tconn->all_tconn);
+       struct drbd_tconn *tconn = container_of(kref, struct drbd_tconn, kref);
+
        idr_destroy(&tconn->volumes);
 
        free_cpumask_var(tconn->cpu_mask);
@@ -2503,7 +2514,9 @@ enum drbd_ret_code conn_new_minor(struct drbd_tconn *tconn, unsigned int minor,
        if (!mdev)
                return ERR_NOMEM;
 
+       kref_get(&tconn->kref);
        mdev->tconn = tconn;
+
        mdev->minor = minor;
        mdev->vnr = vnr;
 
@@ -2605,6 +2618,7 @@ out_no_disk:
        blk_cleanup_queue(q);
 out_no_q:
        kfree(mdev);
+       kref_put(&tconn->kref, &conn_destroy);
        return err;
 }
 

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index fff11ae..23c34ba 100644 (file)
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -479,6 +479,7 @@ static int _try_outdate_peer_async(void *data)
 
        conn_try_outdate_peer(tconn);
 
+       kref_put(&tconn->kref, &conn_destroy);
        return 0;
 }
 
@@ -486,9 +487,12 @@ void conn_try_outdate_peer_async(struct drbd_tconn *tconn)
 {
        struct task_struct *opa;
 
+       kref_get(&tconn->kref);
        opa = kthread_run(_try_outdate_peer_async, tconn, "drbd_async_h");
-       if (IS_ERR(opa))
+       if (IS_ERR(opa)) {
                conn_err(tconn, "out of mem, failed to invoke fence-peer helper\n");
+               kref_put(&tconn->kref, &conn_destroy);
+       }
 }
 
 enum drbd_state_rv
@@ -2627,7 +2631,7 @@ int get_one_status(struct sk_buff *skb, struct netlink_callback *cb)
         * on each iteration.
         */
 
-       /* synchronize with drbd_new_tconn/drbd_free_tconn */
+       /* synchronize with conn_create()/conn_destroy() */
        down_read(&drbd_cfg_rwsem);
        /* revalidate iterator position */
        list_for_each_entry(tmp, &drbd_tconns, all_tconn) {
@@ -2932,7 +2936,7 @@ int drbd_adm_create_connection(struct sk_buff *skb, struct genl_info *info)
                goto out;
        }
 
-       if (!drbd_new_tconn(adm_ctx.conn_name))
+       if (!conn_create(adm_ctx.conn_name))
                retcode = ERR_NOMEM;
 out:
        drbd_adm_finish(info, retcode);
@@ -3005,10 +3009,6 @@ int drbd_adm_delete_minor(struct sk_buff *skb, struct genl_info *info)
        down_write(&drbd_cfg_rwsem);
        retcode = adm_delete_minor(adm_ctx.mdev);
        up_write(&drbd_cfg_rwsem);
-       /* if this was the last volume of this connection,
-        * this will terminate all threads */
-       if (retcode == NO_ERROR)
-               conn_reconfig_done(adm_ctx.tconn);
 out:
        drbd_adm_finish(info, retcode);
        return 0;
@@ -3078,7 +3078,9 @@ int drbd_adm_down(struct sk_buff *skb, struct genl_info *info)
 
        /* delete connection */
        if (conn_lowest_minor(adm_ctx.tconn) < 0) {
-               drbd_free_tconn(adm_ctx.tconn);
+               list_del(&adm_ctx.tconn->all_tconn);
+               kref_put(&adm_ctx.tconn->kref, &conn_destroy);
+
                retcode = NO_ERROR;
        } else {
                /* "can not happen" */
@@ -3107,7 +3109,9 @@ int drbd_adm_delete_connection(struct sk_buff *skb, struct genl_info *info)
 
        down_write(&drbd_cfg_rwsem);
        if (conn_lowest_minor(adm_ctx.tconn) < 0) {
-               drbd_free_tconn(adm_ctx.tconn);
+               list_del(&adm_ctx.tconn->all_tconn);
+               kref_put(&adm_ctx.tconn->kref, &conn_destroy);
+
                retcode = NO_ERROR;
        } else {
                retcode = ERR_CONN_IN_USE;

diff --git a/drivers/block/drbd/drbd_state.c b/drivers/block/drbd/drbd_state.c
index f20a4a3..d7a330e 100644 (file)
--- a/drivers/block/drbd/drbd_state.c
+++ b/drivers/block/drbd/drbd_state.c
@@ -1460,6 +1460,7 @@ static int w_after_conn_state_ch(struct drbd_work *w, int unused)
 
        //conn_err(tconn, STATE_FMT, STATE_ARGS("nms", nms));
        after_all_state_ch(tconn);
+       kref_put(&tconn->kref, &conn_destroy);
 
        return 0;
 }
@@ -1686,6 +1687,7 @@ _conn_request_state(struct drbd_tconn *tconn, union drbd_state mask, union drbd_
                acscw->ns_max = ns_max;
                acscw->flags = flags;
                acscw->w.cb = w_after_conn_state_ch;
+               kref_get(&tconn->kref);
                acscw->w.tconn = tconn;
                drbd_queue_work(&tconn->data.work, &acscw->w);
        } else {