[PATCH] IB: allow NULL sa_query callbacks

Check if a client passes a NULL callback into an SA query, and if so, never
call back.  This fixes an oops if someone unloads ib_ipoib and ib_sa in
rapid succession.  ib_ipoib does an MCMember delete with a NULL callback
and 0 timeout on unload, which is usually fine since the delete completes
successfully.  However, if ib_sa is unloaded immediately afterwards, the
delete will be canceled and ib_sa will try to call the (now already
unloaded) ib_ipoib module back with the cancel completion, which triggers
the oops.

Signed-off-by: Roland Dreier <roland@topspin.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/infiniband/core/sa_query.c b/drivers/infiniband/core/sa_query.c
index d4233ee..276e1a5 100644 (file)
--- a/drivers/infiniband/core/sa_query.c
+++ b/drivers/infiniband/core/sa_query.c
@@ -587,7 +587,7 @@ int ib_sa_path_rec_get(struct ib_device *device, u8 port_num,
 
        init_mad(query->sa_query.mad, agent);
 
-       query->sa_query.callback              = ib_sa_path_rec_callback;
+       query->sa_query.callback              = callback ? ib_sa_path_rec_callback : NULL;
        query->sa_query.release               = ib_sa_path_rec_release;
        query->sa_query.port                  = port;
        query->sa_query.mad->mad_hdr.method   = IB_MGMT_METHOD_GET;
@@ -663,7 +663,7 @@ int ib_sa_mcmember_rec_query(struct ib_device *device, u8 port_num,
 
        init_mad(query->sa_query.mad, agent);
 
-       query->sa_query.callback              = ib_sa_mcmember_rec_callback;
+       query->sa_query.callback              = callback ? ib_sa_mcmember_rec_callback : NULL;
        query->sa_query.release               = ib_sa_mcmember_rec_release;
        query->sa_query.port                  = port;
        query->sa_query.mad->mad_hdr.method   = method;
@@ -698,20 +698,21 @@ static void send_handler(struct ib_mad_agent *agent,
        if (!query)
                return;
 
-       switch (mad_send_wc->status) {
-       case IB_WC_SUCCESS:
-               /* No callback -- already got recv */
-               break;
-       case IB_WC_RESP_TIMEOUT_ERR:
-               query->callback(query, -ETIMEDOUT, NULL);
-               break;
-       case IB_WC_WR_FLUSH_ERR:
-               query->callback(query, -EINTR, NULL);
-               break;
-       default:
-               query->callback(query, -EIO, NULL);
-               break;
-       }
+       if (query->callback)
+               switch (mad_send_wc->status) {
+               case IB_WC_SUCCESS:
+                       /* No callback -- already got recv */
+                       break;
+               case IB_WC_RESP_TIMEOUT_ERR:
+                       query->callback(query, -ETIMEDOUT, NULL);
+                       break;
+               case IB_WC_WR_FLUSH_ERR:
+                       query->callback(query, -EINTR, NULL);
+                       break;
+               default:
+                       query->callback(query, -EIO, NULL);
+                       break;
+               }
 
        dma_unmap_single(agent->device->dma_device,
                         pci_unmap_addr(query, mapping),
@@ -736,7 +737,7 @@ static void recv_handler(struct ib_mad_agent *mad_agent,
        query = idr_find(&query_idr, mad_recv_wc->wc->wr_id);
        spin_unlock_irqrestore(&idr_lock, flags);
 
-       if (query) {
+       if (query && query->callback) {
                if (mad_recv_wc->wc->status == IB_WC_SUCCESS)
                        query->callback(query,
                                        mad_recv_wc->recv_buf.mad->mad_hdr.status ?