FAILED: Patch "cifs: Fix locking usage for tcon fields" failed to apply to 5.10-stable tree

Sasha Levin
2026-03-01T02:03:35Z

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From 96c4af418586ee9a6aab61738644366426e05316 Mon Sep 17 00:00:00 2001
From: Shyam Prasad N <sprasad@microsoft.com>
Date: Sun, 1 Feb 2026 00:21:13 +0530
Subject: [PATCH] cifs: Fix locking usage for tcon fields

We used to use the cifs_tcp_ses_lock to protect a lot of objects
that are not just the server, ses or tcon lists. We later introduced
srv_lock, ses_lock and tc_lock to protect fields within the
corresponding structs. This was done to provide a more granular
protection and avoid unnecessary serialization.

There were still a couple of uses of cifs_tcp_ses_lock to provide
tcon fields. In this patch, I've replaced them with tc_lock.

Cc: stable@vger.kernel.org
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
---
fs/smb/client/cached_dir.c | 4 ++--
fs/smb/client/smb2misc.c | 6 +++---
fs/smb/client/smb2ops.c | 8 +++-----
fs/smb/client/smb2pdu.c | 2 ++
fs/smb/client/trace.h | 1 +
5 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/fs/smb/client/cached_dir.c b/fs/smb/client/cached_dir.c
index df9977030d199..2a6b8ce80be23 100644
--- a/fs/smb/client/cached_dir.c
+++ b/fs/smb/client/cached_dir.c
@@ -792,11 +792,11 @@ static void cfids_laundromat_worker(struct work_struct *work)
cfid->dentry = NULL;

if (cfid->is_open) {
- spin_lock(&cifs_tcp_ses_lock);
+ spin_lock(&cfid->tcon->tc_lock);
++cfid->tcon->tc_count;
trace_smb3_tcon_ref(cfid->tcon->debug_id, cfid->tcon->tc_count,
netfs_trace_tcon_ref_get_cached_laundromat);
- spin_unlock(&cifs_tcp_ses_lock);
+ spin_unlock(&cfid->tcon->tc_lock);
queue_work(serverclose_wq, &cfid->close_work);
} else
/*
diff --git a/fs/smb/client/smb2misc.c b/fs/smb/client/smb2misc.c
index f3cb62d914502..0871b9f1f86a6 100644
--- a/fs/smb/client/smb2misc.c
+++ b/fs/smb/client/smb2misc.c
@@ -820,14 +820,14 @@ smb2_handle_cancelled_close(struct cifs_tcon *tcon, __u64 persistent_fid,
int rc;

cifs_dbg(FYI, "%s: tc_count=%d\n", __func__, tcon->tc_count);
- spin_lock(&cifs_tcp_ses_lock);
+ spin_lock(&tcon->tc_lock);
if (tcon->tc_count <= 0) {
struct TCP_Server_Info *server = NULL;

trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
netfs_trace_tcon_ref_see_cancelled_close);
WARN_ONCE(tcon->tc_count < 0, "tcon refcount is negative");
- spin_unlock(&cifs_tcp_ses_lock);
+ spin_unlock(&tcon->tc_lock);

if (tcon->ses) {
server = tcon->ses->server;
@@ -841,7 +841,7 @@ smb2_handle_cancelled_close(struct cifs_tcon *tcon, __u64 persistent_fid,
tcon->tc_count++;
trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
netfs_trace_tcon_ref_get_cancelled_close);
- spin_unlock(&cifs_tcp_ses_lock);
+ spin_unlock(&tcon->tc_lock);

rc = __smb2_handle_cancelled_cmd(tcon, SMB2_CLOSE_HE, 0,
persistent_fid, volatile_fid);
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index f6806946d0eee..653e2f29384d4 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -3107,7 +3107,9 @@ smb2_get_dfs_refer(const unsigned int xid, struct cifs_ses *ses,
struct cifs_tcon,
tcon_list);
if (tcon) {
+ spin_lock(&tcon->tc_lock);
tcon->tc_count++;
+ spin_unlock(&tcon->tc_lock);
trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
netfs_trace_tcon_ref_get_dfs_refer);
}
@@ -3176,13 +3178,9 @@ smb2_get_dfs_refer(const unsigned int xid, struct cifs_ses *ses,
out:
if (tcon && !tcon->ipc) {
/* ipc tcons are not refcounted */
- spin_lock(&cifs_tcp_ses_lock);
- tcon->tc_count--;
+ cifs_put_tcon(tcon, netfs_trace_tcon_ref_put_dfs_refer);
trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
netfs_trace_tcon_ref_dec_dfs_refer);
- /* tc_count can never go negative */
- WARN_ON(tcon->tc_count < 0);
- spin_unlock(&cifs_tcp_ses_lock);
}
kfree(utf16_path);
kfree(dfs_req);
diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index fa22702a61a6e..a88b21e5b30e2 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -4263,7 +4263,9 @@ void smb2_reconnect_server(struct work_struct *work)

list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
if (tcon->need_reconnect || tcon->need_reopen_files) {
+ spin_lock(&tcon->tc_lock);
tcon->tc_count++;
+ spin_unlock(&tcon->tc_lock);
trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
netfs_trace_tcon_ref_get_reconnect_server);
list_add_tail(&tcon->rlist, &tmp_list);
diff --git a/fs/smb/client/trace.h b/fs/smb/client/trace.h
index a584a77431132..191f02344dcdd 100644
--- a/fs/smb/client/trace.h
+++ b/fs/smb/client/trace.h
@@ -189,6 +189,7 @@
EM(netfs_trace_tcon_ref_put_cancelled_close_fid, "PUT Cn-Fid") \
EM(netfs_trace_tcon_ref_put_cancelled_mid, "PUT Cn-Mid") \
EM(netfs_trace_tcon_ref_put_mnt_ctx, "PUT MntCtx") \
+ EM(netfs_trace_tcon_ref_put_dfs_refer, "PUT DfsRfr") \
EM(netfs_trace_tcon_ref_put_reconnect_server, "PUT Reconn") \
EM(netfs_trace_tcon_ref_put_tlink, "PUT Tlink ") \
EM(netfs_trace_tcon_ref_see_cancelled_close, "SEE Cn-Cls") \
--
2.51.0