iwlwifi: pcie: detect the DMA bug and warn if it happens

Warn if the DMA bug is going to happen. We don't have a good
way of actually aborting in this case and we have workarounds
in place for the cases where it happens, but in order to not
be surprised add a safety-check and warn.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c b/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c
index 8abadfbc793a335348c6d29743e83b99c90f1ce9..a2dc380ac17c321a249eb3cf891c6b9ea28e1ae3 100644 (file)
--- a/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c
+++ b/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c
@@ -231,6 +231,17 @@ static int iwl_pcie_gen2_set_tb(struct iwl_trans *trans,
        int idx = iwl_pcie_gen2_get_num_tbs(trans, tfd);
        struct iwl_tfh_tb *tb;
 
+       /*
+        * Only WARN here so we know about the issue, but we mess up our
+        * unmap path because not every place currently checks for errors
+        * returned from this function - it can only return an error if
+        * there's no more space, and so when we know there is enough we
+        * don't always check ...
+        */
+       WARN(crosses_4g_boundary(addr, len),
+            "possible DMA problem with iova:0x%llx, len:%d\n",
+            (unsigned long long)addr, len);
+
        if (WARN_ON(idx >= IWL_TFH_NUM_TBS))
                return -EINVAL;
        tb = &tfd->tbs[idx];