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scoutfs: add conn destroy workq

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Lockdep gets angry when we try to destroy an accepted conn workqueue
from within work in a listening conn's workqueue.  It doesn't recognize
that they have a hierarchical relationship that maintains a consistent
order and we can't get at the workqueue lockdep_map to set subclasses.
We add a destroy workqueue which will have its own class.

Signed-off-by: Zach Brown <zab@versity.com>
This commit is contained in:
Zach Brown
2019-07-30 09:42:23 -07:00
committed by Zach Brown
parent 319ff86014
commit feaf17c3a5
3 changed files with 39 additions and 2 deletions
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32
kmod/src/net.c
View File

@@ -80,6 +80,7 @@
*/
struct net_info {
struct workqueue_struct *shutdown_workq;
struct workqueue_struct *destroy_workq;
struct dentry *conn_tseq_dentry;
struct scoutfs_tseq_tree conn_tseq_tree;
struct dentry *msg_tseq_dentry;
@@ -796,14 +797,25 @@ static void scoutfs_net_send_worker(struct work_struct *work)
trace_scoutfs_net_send_work_exit(sb, 0, ret);
}
static void destroy_conn(struct scoutfs_net_connection *conn)
/*
* Listening conns try to destroy accepted conns. Workqueues model
* flushing work as acquiring a workqueue class lock so it thinks that
* this is a deadlock because it doesn't know about our hierarchy of
* workqueues. The workqueue lockdep_map is private so we can't set a
* subclass to differentiate between listening and accepted conn
* workqueues. Instead we queue final conn destruction off to a longer
* lived specific workqueue that has a different class.
*/
static void scoutfs_net_destroy_worker(struct work_struct *work)
{
DEFINE_CONN_FROM_WORK(conn, work, destroy_work);
struct super_block *sb = conn->sb;
struct net_info *ninf = SCOUTFS_SB(sb)->net_info;
struct scoutfs_net_connection *listener;
struct message_send *msend;
struct message_send *tmp;
trace_scoutfs_net_destroy_work_enter(sb, 0, 0);
trace_scoutfs_conn_destroy_start(conn);
WARN_ON_ONCE(conn->sock != NULL);
@@ -835,6 +847,15 @@ static void destroy_conn(struct scoutfs_net_connection *conn)
kfree(conn->info);
trace_scoutfs_conn_destroy_free(conn);
kfree(conn);
trace_scoutfs_net_destroy_work_exit(sb, 0, 0);
}
static void destroy_conn(struct scoutfs_net_connection *conn)
{
struct net_info *ninf = SCOUTFS_SB(conn->sb)->net_info;
queue_work(ninf->destroy_workq, &conn->destroy_work);
}
/*
@@ -1286,6 +1307,7 @@ scoutfs_net_alloc_conn(struct super_block *sb,
INIT_WORK(&conn->send_work, scoutfs_net_send_worker);
INIT_WORK(&conn->recv_work, scoutfs_net_recv_worker);
INIT_WORK(&conn->shutdown_work, scoutfs_net_shutdown_worker);
INIT_WORK(&conn->destroy_work, scoutfs_net_destroy_worker);
INIT_DELAYED_WORK(&conn->reconn_free_dwork,
scoutfs_net_reconn_free_worker);
@@ -1317,6 +1339,7 @@ void scoutfs_net_shutdown(struct super_block *sb,
{
shutdown_conn(conn);
flush_work(&conn->shutdown_work);
flush_work(&conn->destroy_work);
}
/*
@@ -1843,7 +1866,10 @@ int scoutfs_net_setup(struct super_block *sb)
ninf->shutdown_workq = alloc_workqueue("scoutfs_net_shutdown",
WQ_UNBOUND | WQ_NON_REENTRANT,
0);
if (!ninf->shutdown_workq) {
ninf->destroy_workq = alloc_workqueue("scoutfs_net_destroy",
WQ_UNBOUND | WQ_NON_REENTRANT,
0);
if (!ninf->shutdown_workq || !ninf->destroy_workq) {
ret = -ENOMEM;
goto out;
}
@@ -1879,6 +1905,8 @@ void scoutfs_net_destroy(struct super_block *sb)
if (ninf) {
if (ninf->shutdown_workq)
destroy_workqueue(ninf->shutdown_workq);
if (ninf->destroy_workq)
destroy_workqueue(ninf->destroy_workq);
debugfs_remove(ninf->conn_tseq_dentry);
debugfs_remove(ninf->msg_tseq_dentry);
kfree(ninf);

1
kmod/src/net.h
View File

@@ -67,6 +67,7 @@ struct scoutfs_net_connection {
struct work_struct send_work;
struct work_struct recv_work;
struct work_struct shutdown_work;
struct work_struct destroy_work;
struct delayed_work reconn_free_dwork;
/* message_recv proc_work also executes in the conn workq */

8
kmod/src/scoutfs_trace.h
View File

@@ -2001,6 +2001,14 @@ DEFINE_EVENT(scoutfs_work_class, scoutfs_net_shutdown_work_exit,
TP_PROTO(struct super_block *sb, u64 data, int ret),
TP_ARGS(sb, data, ret)
);
DEFINE_EVENT(scoutfs_work_class, scoutfs_net_destroy_work_enter,
TP_PROTO(struct super_block *sb, u64 data, int ret),
TP_ARGS(sb, data, ret)
);
DEFINE_EVENT(scoutfs_work_class, scoutfs_net_destroy_work_exit,
TP_PROTO(struct super_block *sb, u64 data, int ret),
TP_ARGS(sb, data, ret)
);
DEFINE_EVENT(scoutfs_work_class, scoutfs_net_reconn_free_work_enter,
TP_PROTO(struct super_block *sb, u64 data, int ret),
TP_ARGS(sb, data, ret)