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cifs: add a warning if we try to to dequeue a deleted mid

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cifs_delete_mid() is called once we are finished handling a mid and we
expect no more work done on this mid.

Needed to fix recent commit:
commit 730928c8f4be88e9d6a027a16b1e8fa9c59fc077
("cifs: update smb2_queryfs() to use compounding")

Add a warning if someone tries to dequeue a mid that has already been
flagged to be deleted.
Also change list_del() to list_del_init() so that if we have similar bugs
resurface in the future we will not oops.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
This commit is contained in:
Ronnie Sahlberg 2018-08-30 10:12:59 +10:00 committed by Steve French
parent 0595751f26
commit ddf83afb9f
3 changed files with 12 additions and 2 deletions
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1
fs/cifs/cifsglob.h
View File

@ -1553,6 +1553,7 @@ static inline void free_dfs_info_array(struct dfs_info3_param *param,
/* 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 */

8
fs/cifs/connect.c
View File

@ -659,6 +659,14 @@ dequeue_mid(struct mid_q_entry *mid, bool malformed)
mid->mid_state = MID_RESPONSE_RECEIVED;
else
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)
printk_once(KERN_WARNING
"trying to dequeue a deleted mid\n");
else
list_del_init(&mid->qhead);
spin_unlock(&GlobalMid_Lock);
}

3
fs/cifs/transport.c
View File

@ -142,7 +142,8 @@ void
cifs_delete_mid(struct mid_q_entry *mid)
{
spin_lock(&GlobalMid_Lock);
list_del(&mid->qhead);
list_del_init(&mid->qhead);
mid->mid_flags |= MID_DELETED;
spin_unlock(&GlobalMid_Lock);
DeleteMidQEntry(mid);