dialog: functions to search dialog by uuid and keep table entry locked

- helper macros to lock/unlock table entry with dlg cell structure

(cherry picked from commit a4f8c02)

src/modules/dialog/dlg_hash.c

@@ -762,9 +762,10 @@ int dlg_update_rr_set(struct dlg_cell * dlg, unsigned int leg, str *rr)
  * the reference counter by one again iff a dialog has been found.
  * \param h_entry number of the hash table entry
  * \param h_id id of the hash table entry
+ * \param lmode id if 0, then dlg table entry is unlocked, otherwise is locked
  * \return dialog structure on success, NULL on failure
  */
-dlg_cell_t *dlg_lookup( unsigned int h_entry, unsigned int h_id)
+dlg_cell_t *dlg_lookup_mode(unsigned int h_entry, unsigned int h_id, int lmode)
 {
 	dlg_cell_t *dlg;
 	dlg_entry_t *d_entry;
@@ -777,24 +778,59 @@ dlg_cell_t *dlg_lookup( unsigned int h_entry, unsigned int h_id)
 
 	d_entry = &(d_table->entries[h_entry]);
 
-	dlg_lock( d_table, d_entry);
+	dlg_lock(d_table, d_entry);
 
 	for( dlg=d_entry->first ; dlg ; dlg=dlg->next ) {
 		if (dlg->h_id == h_id) {
 			ref_dlg_unsafe(dlg, 1);
-			dlg_unlock( d_table, d_entry);
+			if (likely(lmode == 0)) {
+				dlg_unlock(d_table, d_entry);
+			}
 			LM_DBG("dialog id=%u found on entry %u\n", h_id, h_entry);
 			return dlg;
 		}
 	}
 
-	dlg_unlock( d_table, d_entry);
+	dlg_unlock(d_table, d_entry);
 not_found:
 	LM_DBG("no dialog id=%u found on entry %u\n", h_id, h_entry);
 	return 0;
 }
 
 
+/*!
+ * \brief Lookup a dialog in the global list
+ *
+ * Note that the caller is responsible for decrementing (or reusing)
+ * the reference counter by one again iff a dialog has been found.
+ * \param h_entry number of the hash table entry
+ * \param h_id id of the hash table entry
+ * \return dialog structure on success, NULL on failure
+ */
+dlg_cell_t *dlg_lookup(unsigned int h_entry, unsigned int h_id)
+{
+	return dlg_lookup_mode(h_entry, h_id, 0);
+}
+
+/*!
+ * \brief Search a dialog in the global list by iuid
+ *
+ * Note that the caller is responsible for decrementing (or reusing)
+ * the reference counter by one again if a dialog has been found.
+ * \param diuid internal unique id per dialog
+ * \param lmode id if 0, then dlg table entry is unlocked, otherwise is locked
+ * \return dialog structure on success, NULL on failure
+ */
+dlg_cell_t* dlg_get_by_iuid_mode(dlg_iuid_t *diuid, int lmode)
+{
+	if(diuid==NULL)
+		return NULL;
+	if(diuid->h_id==0)
+		return NULL;
+	/* dlg ref counter is increased by next line */
+	return dlg_lookup_mode(diuid->h_entry, diuid->h_id, lmode);
+}
+
 /*!
  * \brief Search a dialog in the global list by iuid
  *
@@ -810,7 +846,7 @@ dlg_cell_t* dlg_get_by_iuid(dlg_iuid_t *diuid)
 	if(diuid->h_id==0)
 		return NULL;
 	/* dlg ref counter is increased by next line */
-	return dlg_lookup(diuid->h_entry, diuid->h_id);
+	return dlg_lookup_mode(diuid->h_entry, diuid->h_id, 0);
 }
 
 /*!

src/modules/dialog/dlg_hash.h

@@ -201,6 +201,21 @@ extern dlg_table_t *d_table;
 			} \
 		} while(0)
 
+/*!
+ * \brief Set a dialog lock (re-entrant)
+ * \param _dlg dialog cell
+ */
+#define dlg_cell_lock(_dlg) \
+	dlg_lock(d_table, &(d_table->entries[(_dlg)->h_entry]))
+
+/*!
+ * \brief Set a dialog lock (re-entrant)
+ * \param _dlg dialog cell
+ */
+#define dlg_cell_unlock(_dlg) \
+	dlg_unlock(d_table, &(d_table->entries[(_dlg)->h_entry]))
+
+
 /*!
  * \brief Unlink a dialog from the list without locking
  * \see unref_dlg_unsafe