Updated patch (with fix merged into it) attached - and pushed to
for-next pending review and testing
On Wed, Jan 31, 2024 at 4:43 PM Steve French <smfrench@xxxxxxxxx> wrote:
>
> Looks like the patch in for-next "cifs: make sure that channel scaling
> is done only once" (see attached) was missing some unlocks that were
> noticed by compile with C=1 and/or sparse. See below.
>
>
> diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
> index 2837fc4465a7..3110aabc32c5 100644
> --- a/fs/smb/client/smb2pdu.c
> +++ b/fs/smb/client/smb2pdu.c
> @@ -400,8 +400,11 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
> }
>
> spin_lock(&ses->ses_lock);
> - if (ses->flags & CIFS_SES_FLAG_SCALE_CHANNELS)
> + if (ses->flags & CIFS_SES_FLAG_SCALE_CHANNELS) {
> + spin_unlock(&ses->ses_lock);
> + mutex_unlock(&ses->session_mutex);
> goto skip_add_channels;
> + }
> ses->flags |= CIFS_SES_FLAG_SCALE_CHANNELS;
> spin_unlock(&ses->ses_lock);
>
>
> --
> Thanks,
>
> Steve
--
Thanks,
Steve
From ee36a3b345c433a846effcdcfba437c2298eeda5 Mon Sep 17 00:00:00 2001
From: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
Date: Mon, 29 Jan 2024 13:58:13 +0000
Subject: [PATCH] cifs: make sure that channel scaling is done only once
Following a successful cifs_tree_connect, we have the code
to scale up/down the number of channels in the session.
However, it is not protected by a lock today.
As a result, this code can be executed by several processes
that select the same channel. The core functions handle this
well, as they pick chan_lock. However, we've seen cases where
smb2_reconnect throws some warnings.
To fix that, this change introduces a flags bitmap inside the
cifs_ses structure. A new flag type is used to ensure that
only one process enters this section at any time.
Signed-off-by: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
---
fs/smb/client/cifsglob.h | 3 +++
fs/smb/client/smb2pdu.c | 20 +++++++++++++++++---
2 files changed, 20 insertions(+), 3 deletions(-)
diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index 16befff4cbb4..9093c507042f 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -1032,6 +1032,8 @@ struct cifs_chan {
__u8 signkey[SMB3_SIGN_KEY_SIZE];
};
+#define CIFS_SES_FLAG_SCALE_CHANNELS (0x1)
+
/*
* Session structure. One of these for each uid session with a particular host
*/
@@ -1064,6 +1066,7 @@ struct cifs_ses {
enum securityEnum sectype; /* what security flavor was specified? */
bool sign; /* is signing required? */
bool domainAuto:1;
+ unsigned int flags;
__u16 session_flags;
__u8 smb3signingkey[SMB3_SIGN_KEY_SIZE];
__u8 smb3encryptionkey[SMB3_ENC_DEC_KEY_SIZE];
diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index 86f6f35b7f32..6db54c6ef571 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -399,6 +399,15 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
goto out;
}
+ spin_lock(&ses->ses_lock);
+ if (ses->flags & CIFS_SES_FLAG_SCALE_CHANNELS) {
+ spin_unlock(&ses->ses_lock);
+ mutex_unlock(&ses->session_mutex);
+ goto skip_add_channels;
+ }
+ ses->flags |= CIFS_SES_FLAG_SCALE_CHANNELS;
+ spin_unlock(&ses->ses_lock);
+
if (!rc &&
(server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL)) {
mutex_unlock(&ses->session_mutex);
@@ -428,17 +437,22 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
if (ses->chan_max > ses->chan_count &&
ses->iface_count &&
!SERVER_IS_CHAN(server)) {
- if (ses->chan_count == 1)
+ if (ses->chan_count == 1) {
cifs_server_dbg(VFS, "supports multichannel now\n");
+ queue_delayed_work(cifsiod_wq, &tcon->query_interfaces,
+ (SMB_INTERFACE_POLL_INTERVAL * HZ));
+ }
cifs_try_adding_channels(ses);
- queue_delayed_work(cifsiod_wq, &tcon->query_interfaces,
- (SMB_INTERFACE_POLL_INTERVAL * HZ));
}
} else {
mutex_unlock(&ses->session_mutex);
}
+
skip_add_channels:
+ spin_lock(&ses->ses_lock);
+ ses->flags &= ~CIFS_SES_FLAG_SCALE_CHANNELS;
+ spin_unlock(&ses->ses_lock);
if (smb2_command != SMB2_INTERNAL_CMD)
mod_delayed_work(cifsiod_wq, &server->reconnect, 0);
--
2.40.1
