ср, 29 авг. 2018 г. в 17:13, Ronnie Sahlberg <lsahlber@xxxxxxxxxx>:
>
> cifs_delete_mid() is called once we are finished handling a mid and we
> expect no more work done on this mid.
>
> 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@xxxxxxxxxx>
> ---
> fs/cifs/cifsglob.h | 1 +
> fs/cifs/connect.c | 10 +++++++++-
> fs/cifs/transport.c | 3 ++-
> 3 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
> index 0c9ab62c3df4..9dcaed031843 100644
> --- a/fs/cifs/cifsglob.h
> +++ b/fs/cifs/cifsglob.h
> @@ -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 */
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index 4b82cf77da78..216b28e27ad0 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -659,7 +659,15 @@ dequeue_mid(struct mid_q_entry *mid, bool malformed)
> mid->mid_state = MID_RESPONSE_RECEIVED;
> else
> mid->mid_state = MID_RESPONSE_MALFORMED;
> - list_del_init(&mid->qhead);
> + /*
> + * 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);
> }
>
> diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
> index 78f96fa3d7d9..9cc9a127749e 100644
> --- a/fs/cifs/transport.c
> +++ b/fs/cifs/transport.c
> @@ -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);
> --
> 2.13.3
>
Reviewed-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
--
Best regards,
Pavel Shilovsky
