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Subject[PATCH 07/10] drbd: Take a reference on tconn when finding a tconn by name
Date
Rule #3 of kref.txt

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
---
drivers/block/drbd/drbd_int.h | 2 +-
drivers/block/drbd/drbd_main.c | 6 ++++--
drivers/block/drbd/drbd_nl.c | 15 +++++++++++----
3 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 3abf982..7797879 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -1381,7 +1381,7 @@ extern void drbd_delete_device(struct drbd_conf *mdev);

struct drbd_tconn *conn_create(const char *name);
extern void conn_destroy(struct kref *kref);
-struct drbd_tconn *conn_by_name(const char *name);
+struct drbd_tconn *conn_get_by_name(const char *name);
extern void conn_free_crypto(struct drbd_tconn *tconn);

extern int proc_details;
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 1c94d56..02efec5 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -2359,7 +2359,7 @@ static void drbd_init_workqueue(struct drbd_work_queue* wq)
INIT_LIST_HEAD(&wq->q);
}

-struct drbd_tconn *conn_by_name(const char *name)
+struct drbd_tconn *conn_get_by_name(const char *name)
{
struct drbd_tconn *tconn;

@@ -2368,8 +2368,10 @@ struct drbd_tconn *conn_by_name(const char *name)

down_read(&drbd_cfg_rwsem);
list_for_each_entry(tconn, &drbd_tconns, all_tconn) {
- if (!strcmp(tconn->name, name))
+ if (!strcmp(tconn->name, name)) {
+ kref_get(&tconn->kref);
goto found;
+ }
}
tconn = NULL;
found:
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index b854427..3d03114 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -219,7 +219,7 @@ static int drbd_adm_prepare(struct sk_buff *skb, struct genl_info *info,

adm_ctx.minor = d_in->minor;
adm_ctx.mdev = minor_to_mdev(d_in->minor);
- adm_ctx.tconn = conn_by_name(adm_ctx.conn_name);
+ adm_ctx.tconn = conn_get_by_name(adm_ctx.conn_name);

pr_info("adm request: cmd=%u[%s], flags=0x%x, minor=%d, conn=%s\n",
cmd, drbd_genl_cmd_to_str(cmd), d_in->flags,
@@ -251,8 +251,7 @@ static int drbd_adm_prepare(struct sk_buff *skb, struct genl_info *info,
drbd_msg_put_info("minor exists as different volume");
return ERR_INVALID_REQUEST;
}
- if (adm_ctx.mdev && !adm_ctx.tconn)
- adm_ctx.tconn = adm_ctx.mdev->tconn;
+
return NO_ERROR;

fail:
@@ -267,6 +266,11 @@ static int drbd_adm_finish(struct genl_info *info, int retcode)
const char *conn_name = NULL;
const u8 cmd = info->genlhdr->cmd;

+ if (adm_ctx.tconn) {
+ kref_put(&adm_ctx.tconn->kref, &conn_destroy);
+ adm_ctx.tconn = NULL;
+ }
+
if (!adm_ctx.reply_skb)
return -ENOMEM;

@@ -2795,10 +2799,13 @@ int drbd_adm_get_status_all(struct sk_buff *skb, struct netlink_callback *cb)
if (!nla)
return -EINVAL;
conn_name = nla_data(nla);
- tconn = conn_by_name(conn_name);
+ tconn = conn_get_by_name(conn_name);
+
if (!tconn)
return -ENODEV;

+ kref_put(&tconn->kref, &conn_destroy); /* get_one_status() (re)validates tconn by itself */
+
/* prime iterators, and set "filter" mode mark:
* only dump this tconn. */
cb->args[0] = (long)tconn;
--
1.7.4.1


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