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Message-Id: <20250804134006.3609555-4-wangzhaolong@huaweicloud.com>
Date: Mon, 4 Aug 2025 21:40:05 +0800
From: Wang Zhaolong <wangzhaolong@...weicloud.com>
To: sfrench@...ba.org,
pshilov@...rosoft.com
Cc: linux-cifs@...r.kernel.org,
samba-technical@...ts.samba.org,
linux-kernel@...r.kernel.org,
chengzhihao1@...wei.com,
wangzhaolong@...weicloud.com,
yi.zhang@...wei.com,
yangerkun@...wei.com
Subject: [PATCH 3/4] smb: client: smb: client: eliminate mid_flags field
This is step 3/4 of a patch series to fix mid_q_entry memory leaks
caused by race conditions in callback execution.
Replace the mid_flags bitmask with dedicated boolean fields to
simplify locking logic and improve code readability:
- Replace MID_DELETED with bool deleted_from_q
- Replace MID_WAIT_CANCELLED with bool wait_cancelled
- Remove mid_flags field entirely
The new boolean fields have clearer semantics:
- deleted_from_q: whether mid has been removed from pending_mid_q
- wait_cancelled: whether request was cancelled during wait
This change reduces memory usage (from 4-byte bitmask to 2 boolean
flags) and eliminates confusion about which lock protects which
flag bits, preparing for per-mid locking in the next patch.
Signed-off-by: Wang Zhaolong <wangzhaolong@...weicloud.com>
---
fs/smb/client/cifsglob.h | 9 +++------
fs/smb/client/connect.c | 10 +++++-----
fs/smb/client/smb2ops.c | 4 ++--
fs/smb/client/transport.c | 12 ++++++------
4 files changed, 16 insertions(+), 19 deletions(-)
diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index 1844afdf1e41..536dff5b4a9c 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -1728,13 +1728,14 @@ struct mid_q_entry {
struct task_struct *creator;
void *resp_buf; /* pointer to received SMB header */
unsigned int resp_buf_size;
int mid_state; /* wish this were enum but can not pass to wait_event */
int mid_rc; /* rc for MID_RC */
- unsigned int mid_flags;
__le16 command; /* smb command code */
unsigned int optype; /* operation type */
+ bool wait_cancelled:1; /* Cancelled while waiting for response */
+ bool deleted_from_q:1; /* Whether Mid has been dequeued frem pending_mid_q */
bool large_buf:1; /* if valid response, is pointer to large buf */
bool multiRsp:1; /* multiple trans2 responses for one request */
bool multiEnd:1; /* both received */
bool decrypted:1; /* decrypted entry */
};
@@ -1892,14 +1893,10 @@ static inline bool is_replayable_error(int error)
#define MID_RESPONSE_MALFORMED 0x10
#define MID_SHUTDOWN 0x20
#define MID_RESPONSE_READY 0x40 /* ready for other process handle the rsp */
#define MID_RC 0x80 /* mid_rc contains custom rc */
-/* Flags */
-#define MID_WAIT_CANCELLED 1 /* Cancelled while waiting for response */
-#define MID_DELETED 2 /* Mid has been dequeued/deleted */
-
/* Types of response buffer returned from SendReceive2 */
#define CIFS_NO_BUFFER 0 /* Response buffer not returned */
#define CIFS_SMALL_BUFFER 1
#define CIFS_LARGE_BUFFER 2
#define CIFS_IOVEC 4 /* array of response buffers */
@@ -2007,11 +2004,11 @@ require use of the stronger protocol */
* GlobalMid_Lock GlobalMaxActiveXid init_cifs
* GlobalCurrentXid
* GlobalTotalActiveXid
* TCP_Server_Info->srv_lock (anything in struct not protected by another lock and can change)
* TCP_Server_Info->mid_queue_lock TCP_Server_Info->pending_mid_q cifs_get_tcp_session
- * (any changes in mid_q_entry fields)
+ * mid_q_entry->deleted_from_q
* TCP_Server_Info->mid_counter_lock TCP_Server_Info->current_mid cifs_get_tcp_session
* TCP_Server_Info->req_lock TCP_Server_Info->in_flight cifs_get_tcp_session
* ->credits
* ->echo_credits
* ->oplock_credits
diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
index 74ad5881ee45..587845a2452d 100644
--- a/fs/smb/client/connect.c
+++ b/fs/smb/client/connect.c
@@ -325,11 +325,11 @@ cifs_abort_connection(struct TCP_Server_Info *server)
list_for_each_entry_safe(mid, nmid, &server->pending_mid_q, qhead) {
kref_get(&mid->refcount);
if (mid->mid_state == MID_REQUEST_SUBMITTED)
mid->mid_state = MID_RETRY_NEEDED;
list_move(&mid->qhead, &retry_list);
- mid->mid_flags |= MID_DELETED;
+ mid->deleted_from_q = true;
}
spin_unlock(&server->mid_queue_lock);
cifs_server_unlock(server);
cifs_dbg(FYI, "%s: issuing mid callbacks\n", __func__);
@@ -886,11 +886,11 @@ is_smb_response(struct TCP_Server_Info *server, unsigned char type)
*/
spin_lock(&server->mid_queue_lock);
list_for_each_entry_safe(mid, nmid, &server->pending_mid_q, qhead) {
kref_get(&mid->refcount);
list_move(&mid->qhead, &dispose_list);
- mid->mid_flags |= MID_DELETED;
+ mid->deleted_from_q = true;
}
spin_unlock(&server->mid_queue_lock);
/* Now try to reconnect once with NetBIOS session. */
server->with_rfc1001 = true;
@@ -964,16 +964,16 @@ dequeue_mid(struct mid_q_entry *mid, bool malformed)
mid->mid_state = MID_RESPONSE_MALFORMED;
/*
* Trying to handle/dequeue a mid after the send_recv()
* function has finished processing it is a bug.
*/
- if (mid->mid_flags & MID_DELETED) {
+ if (mid->deleted_from_q == true) {
spin_unlock(&mid->server->mid_queue_lock);
pr_warn_once("trying to dequeue a deleted mid\n");
} else {
list_del_init(&mid->qhead);
- mid->mid_flags |= MID_DELETED;
+ mid->deleted_from_q = true;
spin_unlock(&mid->server->mid_queue_lock);
}
}
static unsigned int
@@ -1106,11 +1106,11 @@ clean_demultiplex_info(struct TCP_Server_Info *server)
mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
cifs_dbg(FYI, "Clearing mid %llu\n", mid_entry->mid);
kref_get(&mid_entry->refcount);
mid_entry->mid_state = MID_SHUTDOWN;
list_move(&mid_entry->qhead, &dispose_list);
- mid_entry->mid_flags |= MID_DELETED;
+ mid_entry->deleted_from_q = true;
}
spin_unlock(&server->mid_queue_lock);
/* now walk dispose list and issue callbacks */
list_for_each_safe(tmp, tmp2, &dispose_list) {
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index da2cb9585404..2643d86a5b5f 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -407,11 +407,11 @@ __smb2_find_mid(struct TCP_Server_Info *server, char *buf, bool dequeue)
(mid->mid_state == MID_REQUEST_SUBMITTED) &&
(mid->command == shdr->Command)) {
kref_get(&mid->refcount);
if (dequeue) {
list_del_init(&mid->qhead);
- mid->mid_flags |= MID_DELETED;
+ mid->deleted_from_q = true;
}
spin_unlock(&server->mid_queue_lock);
return mid;
}
}
@@ -4815,11 +4815,11 @@ static void smb2_decrypt_offload(struct work_struct *work)
spin_unlock(&dw->server->srv_lock);
mid->callback(mid);
} else {
spin_lock(&dw->server->mid_queue_lock);
mid->mid_state = MID_REQUEST_SUBMITTED;
- mid->mid_flags &= ~(MID_DELETED);
+ mid->deleted_from_q = false;
list_add_tail(&mid->qhead,
&dw->server->pending_mid_q);
spin_unlock(&dw->server->mid_queue_lock);
spin_unlock(&dw->server->srv_lock);
}
diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c
index 8037accc3987..ca9358c24ceb 100644
--- a/fs/smb/client/transport.c
+++ b/fs/smb/client/transport.c
@@ -87,11 +87,11 @@ void __release_mid(struct kref *refcount)
unsigned long now;
unsigned long roundtrip_time;
#endif
struct TCP_Server_Info *server = midEntry->server;
- if (midEntry->resp_buf && (midEntry->mid_flags & MID_WAIT_CANCELLED) &&
+ if (midEntry->resp_buf && (midEntry->wait_cancelled) &&
(midEntry->mid_state == MID_RESPONSE_RECEIVED ||
midEntry->mid_state == MID_RESPONSE_READY) &&
server->ops->handle_cancelled_mid)
server->ops->handle_cancelled_mid(midEntry, server);
@@ -159,13 +159,13 @@ void __release_mid(struct kref *refcount)
void
delete_mid(struct mid_q_entry *mid)
{
spin_lock(&mid->server->mid_queue_lock);
- if (!(mid->mid_flags & MID_DELETED)) {
+ if (mid->deleted_from_q == false) {
list_del_init(&mid->qhead);
- mid->mid_flags |= MID_DELETED;
+ mid->deleted_from_q = true;
}
spin_unlock(&mid->server->mid_queue_lock);
release_mid(mid);
}
@@ -896,13 +896,13 @@ cifs_sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
break;
case MID_RC:
rc = mid->mid_rc;
break;
default:
- if (!(mid->mid_flags & MID_DELETED)) {
+ if (mid->deleted_from_q == false) {
list_del_init(&mid->qhead);
- mid->mid_flags |= MID_DELETED;
+ mid->deleted_from_q = true;
}
spin_unlock(&server->mid_queue_lock);
cifs_server_dbg(VFS, "%s: invalid mid state mid=%llu state=%d\n",
__func__, mid->mid, mid->mid_state);
rc = -EIO;
@@ -1212,11 +1212,11 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
for (; i < num_rqst; i++) {
cifs_server_dbg(FYI, "Cancelling wait for mid %llu cmd: %d\n",
midQ[i]->mid, le16_to_cpu(midQ[i]->command));
send_cancel(server, &rqst[i], midQ[i]);
spin_lock(&server->mid_queue_lock);
- midQ[i]->mid_flags |= MID_WAIT_CANCELLED;
+ midQ[i]->wait_cancelled = true;
if (midQ[i]->mid_state == MID_REQUEST_SUBMITTED ||
midQ[i]->mid_state == MID_RESPONSE_RECEIVED) {
midQ[i]->callback = cifs_cancelled_callback;
cancelled_mid[i] = true;
credits[i].value = 0;
--
2.39.2
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