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drbd: Basic refcounting for drbd_tconn
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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>
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@Philipp-Reisner
Philipp-Reisner committed Nov 8, 2012
1 parent 1d04122 commit 9dc9fbb
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Showing 4 changed files with 35 additions and 14 deletions.
5 changes: 3 additions & 2 deletions drivers/block/drbd/drbd_int.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand Down Expand Up @@ -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);

Expand Down
20 changes: 17 additions & 3 deletions drivers/block/drbd/drbd_main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -509,6 +509,8 @@ static int drbd_thread_setup(void *arg)
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;
}
Expand Down Expand Up @@ -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;
Expand All @@ -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;
}
Expand Down Expand Up @@ -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();
Expand Down Expand Up @@ -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)
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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);

Expand All @@ -2471,9 +2481,10 @@ struct drbd_tconn *drbd_new_tconn(const char *name)
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);
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -2605,6 +2618,7 @@ enum drbd_ret_code conn_new_minor(struct drbd_tconn *tconn, unsigned int minor,
blk_cleanup_queue(q);
out_no_q:
kfree(mdev);
kref_put(&tconn->kref, &conn_destroy);
return err;
}

Expand Down
22 changes: 13 additions & 9 deletions drivers/block/drbd/drbd_nl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -479,16 +479,20 @@ static int _try_outdate_peer_async(void *data)

conn_try_outdate_peer(tconn);

kref_put(&tconn->kref, &conn_destroy);
return 0;
}

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
Expand Down Expand Up @@ -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) {
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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" */
Expand Down Expand Up @@ -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;
Expand Down
2 changes: 2 additions & 0 deletions drivers/block/drbd/drbd_state.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
}
Expand Down Expand Up @@ -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 {
Expand Down

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