6.6-stable review patch. If anyone has any objections, please let me know.
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From: Shyam Prasad N sprasad@microsoft.com
[ Upstream commit 19a4b9d6c372cab6a3b2c9a061a236136fe95274 ]
The delayed work for reconnect takes server struct as a parameter. But it does so without holding a ref to it. Normally, this may not show a problem as the reconnect work is only cancelled on umount.
However, since we now plan to support scaling down of channels, and the scale down can happen from reconnect work itself, we need to fix it.
This change takes a reference on the server struct before it is passed to the delayed work. And drops the reference in the delayed work itself. Or if the delayed work is successfully cancelled, by the process that cancels it.
Signed-off-by: Shyam Prasad N sprasad@microsoft.com Signed-off-by: Steve French stfrench@microsoft.com Stable-dep-of: 78e727e58e54 ("cifs: update iface_last_update on each query-and-update") Signed-off-by: Sasha Levin sashal@kernel.org --- fs/smb/client/connect.c | 27 +++++++++++++++++++++------ fs/smb/client/smb2pdu.c | 23 +++++++++++++---------- 2 files changed, 34 insertions(+), 16 deletions(-)
diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c index a482afa3fa42..2f5be7dcd1f9 100644 --- a/fs/smb/client/connect.c +++ b/fs/smb/client/connect.c @@ -388,7 +388,13 @@ static int __cifs_reconnect(struct TCP_Server_Info *server, spin_unlock(&server->srv_lock); cifs_swn_reset_server_dstaddr(server); cifs_server_unlock(server); - mod_delayed_work(cifsiod_wq, &server->reconnect, 0); + + /* increase ref count which reconnect work will drop */ + spin_lock(&cifs_tcp_ses_lock); + server->srv_count++; + spin_unlock(&cifs_tcp_ses_lock); + if (mod_delayed_work(cifsiod_wq, &server->reconnect, 0)) + cifs_put_tcp_session(server, false); } } while (server->tcpStatus == CifsNeedReconnect);
@@ -518,7 +524,13 @@ static int reconnect_dfs_server(struct TCP_Server_Info *server) spin_unlock(&server->srv_lock); cifs_swn_reset_server_dstaddr(server); cifs_server_unlock(server); - mod_delayed_work(cifsiod_wq, &server->reconnect, 0); + + /* increase ref count which reconnect work will drop */ + spin_lock(&cifs_tcp_ses_lock); + server->srv_count++; + spin_unlock(&cifs_tcp_ses_lock); + if (mod_delayed_work(cifsiod_wq, &server->reconnect, 0)) + cifs_put_tcp_session(server, false); } while (server->tcpStatus == CifsNeedReconnect);
mutex_lock(&server->refpath_lock); @@ -1605,16 +1617,19 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
cancel_delayed_work_sync(&server->echo);
- if (from_reconnect) + if (from_reconnect) { /* * Avoid deadlock here: reconnect work calls * cifs_put_tcp_session() at its end. Need to be sure * that reconnect work does nothing with server pointer after * that step. */ - cancel_delayed_work(&server->reconnect); - else - cancel_delayed_work_sync(&server->reconnect); + if (cancel_delayed_work(&server->reconnect)) + cifs_put_tcp_session(server, from_reconnect); + } else { + if (cancel_delayed_work_sync(&server->reconnect)) + cifs_put_tcp_session(server, from_reconnect); + }
spin_lock(&server->srv_lock); server->tcpStatus = CifsExiting; diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c index 888eb59ad86f..0274ef67457b 100644 --- a/fs/smb/client/smb2pdu.c +++ b/fs/smb/client/smb2pdu.c @@ -3879,12 +3879,6 @@ void smb2_reconnect_server(struct work_struct *work) } spin_unlock(&ses->chan_lock); } - /* - * Get the reference to server struct to be sure that the last call of - * cifs_put_tcon() in the loop below won't release the server pointer. - */ - if (tcon_exist || ses_exist) - server->srv_count++;
spin_unlock(&cifs_tcp_ses_lock);
@@ -3932,13 +3926,17 @@ void smb2_reconnect_server(struct work_struct *work)
done: cifs_dbg(FYI, "Reconnecting tcons and channels finished\n"); - if (resched) + if (resched) { queue_delayed_work(cifsiod_wq, &server->reconnect, 2 * HZ); + mutex_unlock(&pserver->reconnect_mutex); + + /* no need to put tcp session as we're retrying */ + return; + } mutex_unlock(&pserver->reconnect_mutex);
/* now we can safely release srv struct */ - if (tcon_exist || ses_exist) - cifs_put_tcp_session(server, 1); + cifs_put_tcp_session(server, true); }
int @@ -3958,7 +3956,12 @@ SMB2_echo(struct TCP_Server_Info *server) server->ops->need_neg(server)) { spin_unlock(&server->srv_lock); /* No need to send echo on newly established connections */ - mod_delayed_work(cifsiod_wq, &server->reconnect, 0); + spin_lock(&cifs_tcp_ses_lock); + server->srv_count++; + spin_unlock(&cifs_tcp_ses_lock); + if (mod_delayed_work(cifsiod_wq, &server->reconnect, 0)) + cifs_put_tcp_session(server, false); + return rc; } spin_unlock(&server->srv_lock);