caif: Add ref-count to framing layer

Introduce Per-cpu reference for lower part of CAIF Stack.
Before freeing payload is disabled, synchronize_rcu() is called,
and then ref-count verified to be zero.

Signed-off-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 1 deletions

diff --git a/net/caif/cfcnfg.c b/net/caif/cfcnfg.c
index 7892cc084e27..3f4f31fca2c1 100644
--- a/net/caif/cfcnfg.c
+++ b/net/caif/cfcnfg.c
@@ -519,6 +519,13 @@ int cfcnfg_del_phy_layer(struct cfcnfg *cnfg, struct cflayer *phy_layer)
         caif_assert(phy_layer->id == phyid);
         caif_assert(phyinfo->frm_layer->id == phyid);
 
+        /* Fail if reference count is not zero */
+        if (cffrml_refcnt_read(phyinfo->frm_layer) != 0) {
+                pr_info("Wait for device inuse\n");
+                mutex_unlock(&cnfg->lock);
+                return -EAGAIN;
+        }
+
         list_del_rcu(&phyinfo->node);
         synchronize_rcu();
 
@@ -537,7 +544,7 @@ int cfcnfg_del_phy_layer(struct cfcnfg *cnfg, struct cflayer *phy_layer)
         if (phyinfo->phy_layer != frml_dn)
                 kfree(frml_dn);
 
-        kfree(frml);
+        cffrml_free(frml);
         kfree(phyinfo);
         mutex_unlock(&cnfg->lock);