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Message-ID: <TYCP286MB23235FDD8102162698EF3154CAC09@TYCP286MB2323.JPNP286.PROD.OUTLOOK.COM>
Date: Sun, 15 Jan 2023 18:32:06 +0800
From: Dawei Li <set_pte_at@...look.com>
To: linkinjeon@...nel.org, sfrench@...ba.org
Cc: senozhatsky@...omium.org, tom@...pey.com, hyc.lee@...il.com,
linux-cifs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/6] ksmbd: replace rwlock with rcu for concurrenct access on conn list
Currently, racing protection on conn list is implemented as rwlock,
improve it by rcu primitive for its better performance.
Signed-off-by: Dawei Li <set_pte_at@...look.com>
---
fs/ksmbd/connection.c | 30 +++++++++++++++---------------
fs/ksmbd/connection.h | 1 -
fs/ksmbd/smb2pdu.c | 14 +++++++-------
3 files changed, 22 insertions(+), 23 deletions(-)
diff --git a/fs/ksmbd/connection.c b/fs/ksmbd/connection.c
index fd0a288af299..36d1da273edd 100644
--- a/fs/ksmbd/connection.c
+++ b/fs/ksmbd/connection.c
@@ -20,7 +20,7 @@ static DEFINE_MUTEX(init_lock);
static struct ksmbd_conn_ops default_conn_ops;
LIST_HEAD(conn_list);
-DEFINE_RWLOCK(conn_list_lock);
+DEFINE_SPINLOCK(conn_list_lock);
/**
* ksmbd_conn_free() - free resources of the connection instance
@@ -32,9 +32,9 @@ DEFINE_RWLOCK(conn_list_lock);
*/
void ksmbd_conn_free(struct ksmbd_conn *conn)
{
- write_lock(&conn_list_lock);
- list_del(&conn->conns_list);
- write_unlock(&conn_list_lock);
+ spin_lock(&conn_list_lock);
+ list_del_rcu(&conn->conns_list);
+ spin_unlock(&conn_list_lock);
xa_destroy(&conn->sessions);
kvfree(conn->request_buf);
@@ -84,9 +84,9 @@ struct ksmbd_conn *ksmbd_conn_alloc(void)
spin_lock_init(&conn->llist_lock);
INIT_LIST_HEAD(&conn->lock_list);
- write_lock(&conn_list_lock);
- list_add(&conn->conns_list, &conn_list);
- write_unlock(&conn_list_lock);
+ spin_lock(&conn_list_lock);
+ list_add_rcu(&conn->conns_list, &conn_list);
+ spin_unlock(&conn_list_lock);
return conn;
}
@@ -95,15 +95,15 @@ bool ksmbd_conn_lookup_dialect(struct ksmbd_conn *c)
struct ksmbd_conn *t;
bool ret = false;
- read_lock(&conn_list_lock);
- list_for_each_entry(t, &conn_list, conns_list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(t, &conn_list, conns_list) {
if (memcmp(t->ClientGUID, c->ClientGUID, SMB2_CLIENT_GUID_SIZE))
continue;
ret = true;
break;
}
- read_unlock(&conn_list_lock);
+ rcu_read_unlock();
return ret;
}
@@ -402,8 +402,8 @@ static void stop_sessions(void)
struct ksmbd_transport *t;
again:
- read_lock(&conn_list_lock);
- list_for_each_entry(conn, &conn_list, conns_list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(conn, &conn_list, conns_list) {
struct task_struct *task;
t = conn->transport;
@@ -413,12 +413,12 @@ static void stop_sessions(void)
task->comm, task_pid_nr(task));
conn->status = KSMBD_SESS_EXITING;
if (t->ops->shutdown) {
- read_unlock(&conn_list_lock);
+ rcu_read_unlock();
t->ops->shutdown(t);
- read_lock(&conn_list_lock);
+ rcu_read_lock();
}
}
- read_unlock(&conn_list_lock);
+ rcu_read_unlock();
if (!list_empty(&conn_list)) {
schedule_timeout_interruptible(HZ / 10); /* 100ms */
diff --git a/fs/ksmbd/connection.h b/fs/ksmbd/connection.h
index 3643354a3fa7..e41f33a2da7c 100644
--- a/fs/ksmbd/connection.h
+++ b/fs/ksmbd/connection.h
@@ -139,7 +139,6 @@ struct ksmbd_transport {
#define KSMBD_TCP_PEER_SOCKADDR(c) ((struct sockaddr *)&((c)->peer_addr))
extern struct list_head conn_list;
-extern rwlock_t conn_list_lock;
bool ksmbd_conn_alive(struct ksmbd_conn *conn);
void ksmbd_conn_wait_idle(struct ksmbd_conn *conn);
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 771e045c8d4a..c60cfb360f42 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -6915,8 +6915,8 @@ int smb2_lock(struct ksmbd_work *work)
nolock = 1;
/* check locks in connection list */
- read_lock(&conn_list_lock);
- list_for_each_entry(conn, &conn_list, conns_list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(conn, &conn_list, conns_list) {
spin_lock(&conn->llist_lock);
list_for_each_entry_safe(cmp_lock, tmp2, &conn->lock_list, clist) {
if (file_inode(cmp_lock->fl->fl_file) !=
@@ -6932,7 +6932,7 @@ int smb2_lock(struct ksmbd_work *work)
list_del(&cmp_lock->flist);
list_del(&cmp_lock->clist);
spin_unlock(&conn->llist_lock);
- read_unlock(&conn_list_lock);
+ rcu_read_unlock();
locks_free_lock(cmp_lock->fl);
kfree(cmp_lock);
@@ -6954,7 +6954,7 @@ int smb2_lock(struct ksmbd_work *work)
cmp_lock->start > smb_lock->start &&
cmp_lock->start < smb_lock->end) {
spin_unlock(&conn->llist_lock);
- read_unlock(&conn_list_lock);
+ rcu_read_unlock();
pr_err("previous lock conflict with zero byte lock range\n");
goto out;
}
@@ -6963,7 +6963,7 @@ int smb2_lock(struct ksmbd_work *work)
smb_lock->start > cmp_lock->start &&
smb_lock->start < cmp_lock->end) {
spin_unlock(&conn->llist_lock);
- read_unlock(&conn_list_lock);
+ rcu_read_unlock();
pr_err("current lock conflict with zero byte lock range\n");
goto out;
}
@@ -6974,14 +6974,14 @@ int smb2_lock(struct ksmbd_work *work)
cmp_lock->end >= smb_lock->end)) &&
!cmp_lock->zero_len && !smb_lock->zero_len) {
spin_unlock(&conn->llist_lock);
- read_unlock(&conn_list_lock);
+ rcu_read_unlock();
pr_err("Not allow lock operation on exclusive lock range\n");
goto out;
}
}
spin_unlock(&conn->llist_lock);
}
- read_unlock(&conn_list_lock);
+ rcu_read_unlock();
out_check_cl:
if (smb_lock->fl->fl_type == F_UNLCK && nolock) {
pr_err("Try to unlock nolocked range\n");
--
2.25.1
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