Re: [PATCH 06/14] cifs: handle cases where a channel is closed

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This patch wouldn't merge due to a merge conflict here.  Am I missing
an earlier patch of yours before the series?

I have these in for-next:
d1ea8f36fa51 (HEAD -> for-next) cifs: force interface update before a
fresh session setup
1e27cedcaf4e (origin/for-next) cifs: do not reset chan_max if
multichannel is not supported at mount
e257df806ae0 cifs: display the endpoint IP details in DebugData
9d95130c9f78 cifs: reconnect helper should set reconnect for the right channel
7ac6866076bd smb: client: fix use-after-free in smb2_query_info_compound()
0779365fc10d smb: client: remove extra @chan_count check in __cifs_put_smb_ses()
4cf6e1101a25 cifs: add xid to query server interface call
52768695d36a cifs: print server capabilities in DebugData


--- fs/smb/client/connect.c
+++ fs/smb/client/connect.c
@@ -2037,7 +2041,9 @@ void __cifs_put_smb_ses(struct cifs_ses *ses)

kref_put(&ses->chans[i].iface->refcount, release_iface);
                                ses->chans[i].iface = NULL;
                        }
-                       cifs_put_tcp_session(ses->chans[i].server, 0);
+
+                       if (ses->chans[i].server)
+                               cifs_put_tcp_session(ses->chans[i].server, 0);
                        ses->chans[i].server = NULL;
                }
        }

On Mon, Oct 30, 2023 at 6:00 AM <nspmangalore@xxxxxxxxx> wrote:
>
> From: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
>
> So far, SMB multichannel could only scale up, but not
> scale down the number of channels. In this series of
> patch, we now allow the client to deal with the case
> of multichannel disabled on the server when the share
> is mounted. With that change, we now need the ability
> to scale down the channels.
>
> This change allows the client to deal with cases of
> missing channels more gracefully.
>
> Signed-off-by: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
> ---
>  fs/smb/client/cifs_debug.c    |  5 +++++
>  fs/smb/client/cifsglob.h      |  1 +
>  fs/smb/client/cifsproto.h     |  2 +-
>  fs/smb/client/connect.c       | 10 ++++++++--
>  fs/smb/client/sess.c          | 25 +++++++++++++++++++++----
>  fs/smb/client/smb2transport.c |  8 +++++++-
>  6 files changed, 43 insertions(+), 8 deletions(-)
>
> diff --git a/fs/smb/client/cifs_debug.c b/fs/smb/client/cifs_debug.c
> index a9dfecc397a8..9fca09539728 100644
> --- a/fs/smb/client/cifs_debug.c
> +++ b/fs/smb/client/cifs_debug.c
> @@ -136,6 +136,11 @@ cifs_dump_channel(struct seq_file *m, int i, struct cifs_chan *chan)
>  {
>         struct TCP_Server_Info *server = chan->server;
>
> +       if (!server) {
> +               seq_printf(m, "\n\n\t\tChannel: %d DISABLED", i+1);
> +               return;
> +       }
> +
>         seq_printf(m, "\n\n\t\tChannel: %d ConnectionId: 0x%llx"
>                    "\n\t\tNumber of credits: %d,%d,%d Dialect 0x%x"
>                    "\n\t\tTCP status: %d Instance: %d"
> diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
> index 02082621d8e0..552ed441281a 100644
> --- a/fs/smb/client/cifsglob.h
> +++ b/fs/smb/client/cifsglob.h
> @@ -1050,6 +1050,7 @@ struct cifs_ses {
>         spinlock_t chan_lock;
>         /* ========= begin: protected by chan_lock ======== */
>  #define CIFS_MAX_CHANNELS 16
> +#define CIFS_INVAL_CHAN_INDEX (-1)
>  #define CIFS_ALL_CHANNELS_SET(ses)     \
>         ((1UL << (ses)->chan_count) - 1)
>  #define CIFS_ALL_CHANS_GOOD(ses)               \
> diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h
> index 0c37eefa18a5..65c84b3d1a65 100644
> --- a/fs/smb/client/cifsproto.h
> +++ b/fs/smb/client/cifsproto.h
> @@ -616,7 +616,7 @@ bool is_server_using_iface(struct TCP_Server_Info *server,
>  bool is_ses_using_iface(struct cifs_ses *ses, struct cifs_server_iface *iface);
>  void cifs_ses_mark_for_reconnect(struct cifs_ses *ses);
>
> -unsigned int
> +int
>  cifs_ses_get_chan_index(struct cifs_ses *ses,
>                         struct TCP_Server_Info *server);
>  void
> diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
> index 97c9a32cff36..8393977e21ee 100644
> --- a/fs/smb/client/connect.c
> +++ b/fs/smb/client/connect.c
> @@ -173,8 +173,12 @@ cifs_signal_cifsd_for_reconnect(struct TCP_Server_Info *server,
>         list_for_each_entry(ses, &pserver->smb_ses_list, smb_ses_list) {
>                 spin_lock(&ses->chan_lock);
>                 for (i = 0; i < ses->chan_count; i++) {
> +                       if (!ses->chans[i].server)
> +                               continue;
> +
>                         spin_lock(&ses->chans[i].server->srv_lock);
> -                       ses->chans[i].server->tcpStatus = CifsNeedReconnect;
> +                       if (ses->chans[i].server->tcpStatus != CifsExiting)
> +                               ses->chans[i].server->tcpStatus = CifsNeedReconnect;
>                         spin_unlock(&ses->chans[i].server->srv_lock);
>                 }
>                 spin_unlock(&ses->chan_lock);
> @@ -2033,7 +2037,9 @@ void __cifs_put_smb_ses(struct cifs_ses *ses)
>                                 kref_put(&ses->chans[i].iface->refcount, release_iface);
>                                 ses->chans[i].iface = NULL;
>                         }
> -                       cifs_put_tcp_session(ses->chans[i].server, 0);
> +
> +                       if (ses->chans[i].server)
> +                               cifs_put_tcp_session(ses->chans[i].server, 0);
>                         ses->chans[i].server = NULL;
>                 }
>         }
> diff --git a/fs/smb/client/sess.c b/fs/smb/client/sess.c
> index c899b05c92f7..9d2228c2d7e5 100644
> --- a/fs/smb/client/sess.c
> +++ b/fs/smb/client/sess.c
> @@ -69,7 +69,7 @@ bool is_ses_using_iface(struct cifs_ses *ses, struct cifs_server_iface *iface)
>
>  /* channel helper functions. assumed that chan_lock is held by caller. */
>
> -unsigned int
> +int
>  cifs_ses_get_chan_index(struct cifs_ses *ses,
>                         struct TCP_Server_Info *server)
>  {
> @@ -85,14 +85,16 @@ cifs_ses_get_chan_index(struct cifs_ses *ses,
>                 cifs_dbg(VFS, "unable to get chan index for server: 0x%llx",
>                          server->conn_id);
>         WARN_ON(1);
> -       return 0;
> +       return CIFS_INVAL_CHAN_INDEX;
>  }
>
>  void
>  cifs_chan_set_in_reconnect(struct cifs_ses *ses,
>                              struct TCP_Server_Info *server)
>  {
> -       unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
> +       int chan_index = cifs_ses_get_chan_index(ses, server);
> +       if (chan_index == CIFS_INVAL_CHAN_INDEX)
> +               return;
>
>         ses->chans[chan_index].in_reconnect = true;
>  }
> @@ -102,6 +104,8 @@ cifs_chan_clear_in_reconnect(struct cifs_ses *ses,
>                              struct TCP_Server_Info *server)
>  {
>         unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
> +       if (chan_index == CIFS_INVAL_CHAN_INDEX)
> +               return;
>
>         ses->chans[chan_index].in_reconnect = false;
>  }
> @@ -111,6 +115,8 @@ cifs_chan_in_reconnect(struct cifs_ses *ses,
>                           struct TCP_Server_Info *server)
>  {
>         unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
> +       if (chan_index == CIFS_INVAL_CHAN_INDEX)
> +               return true;    /* err on the safer side */
>
>         return CIFS_CHAN_IN_RECONNECT(ses, chan_index);
>  }
> @@ -120,6 +126,8 @@ cifs_chan_set_need_reconnect(struct cifs_ses *ses,
>                              struct TCP_Server_Info *server)
>  {
>         unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
> +       if (chan_index == CIFS_INVAL_CHAN_INDEX)
> +               return;
>
>         set_bit(chan_index, &ses->chans_need_reconnect);
>         cifs_dbg(FYI, "Set reconnect bitmask for chan %u; now 0x%lx\n",
> @@ -131,6 +139,8 @@ cifs_chan_clear_need_reconnect(struct cifs_ses *ses,
>                                struct TCP_Server_Info *server)
>  {
>         unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
> +       if (chan_index == CIFS_INVAL_CHAN_INDEX)
> +               return;
>
>         clear_bit(chan_index, &ses->chans_need_reconnect);
>         cifs_dbg(FYI, "Cleared reconnect bitmask for chan %u; now 0x%lx\n",
> @@ -142,6 +152,8 @@ cifs_chan_needs_reconnect(struct cifs_ses *ses,
>                           struct TCP_Server_Info *server)
>  {
>         unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
> +       if (chan_index == CIFS_INVAL_CHAN_INDEX)
> +               return true;    /* err on the safer side */
>
>         return CIFS_CHAN_NEEDS_RECONNECT(ses, chan_index);
>  }
> @@ -151,6 +163,8 @@ cifs_chan_is_iface_active(struct cifs_ses *ses,
>                           struct TCP_Server_Info *server)
>  {
>         unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
> +       if (chan_index == CIFS_INVAL_CHAN_INDEX)
> +               return true;    /* err on the safer side */
>
>         return ses->chans[chan_index].iface &&
>                 ses->chans[chan_index].iface->is_active;
> @@ -269,7 +283,7 @@ cifs_chan_update_iface(struct cifs_ses *ses, struct TCP_Server_Info *server)
>
>         spin_lock(&ses->chan_lock);
>         chan_index = cifs_ses_get_chan_index(ses, server);
> -       if (!chan_index) {
> +       if (chan_index == CIFS_INVAL_CHAN_INDEX) {
>                 spin_unlock(&ses->chan_lock);
>                 return 0;
>         }
> @@ -319,6 +333,9 @@ cifs_chan_update_iface(struct cifs_ses *ses, struct TCP_Server_Info *server)
>
>         spin_lock(&ses->chan_lock);
>         chan_index = cifs_ses_get_chan_index(ses, server);
> +       if (chan_index == CIFS_INVAL_CHAN_INDEX)
> +               return 0;
> +
>         ses->chans[chan_index].iface = iface;
>
>         /* No iface is found. if secondary chan, drop connection */
> diff --git a/fs/smb/client/smb2transport.c b/fs/smb/client/smb2transport.c
> index 23c50ed7d4b5..84ea67301303 100644
> --- a/fs/smb/client/smb2transport.c
> +++ b/fs/smb/client/smb2transport.c
> @@ -413,7 +413,13 @@ generate_smb3signingkey(struct cifs_ses *ses,
>                       ses->ses_status == SES_GOOD);
>
>         chan_index = cifs_ses_get_chan_index(ses, server);
> -       /* TODO: introduce ref counting for channels when the can be freed */
> +       if (chan_index == CIFS_INVAL_CHAN_INDEX) {
> +               spin_unlock(&ses->chan_lock);
> +               spin_unlock(&ses->ses_lock);
> +
> +               return -EINVAL;
> +       }
> +
>         spin_unlock(&ses->chan_lock);
>         spin_unlock(&ses->ses_lock);
>
> --
> 2.34.1
>


-- 
Thanks,

Steve




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