cmap: Explain corner case in CMAP_FOR_EACH comment.

Commit d916785("dpif-netdev: Fix improper use of CMAP_FOR_EACH.") fixes a problem that's worth documenting. Requested-by: Jarno Rajahalme <[email protected]> Signed-off-by: Daniele Di Proietto <[email protected]> Acked-by: Ben Pfaff <[email protected]>
xnox · Feb 4, 2016 · 25c7da8 · 25c7da8
1 parent e6448d2
commit 25c7da8
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/lib/cmap.h b/lib/cmap.h
@@ -169,6 +169,11 @@ unsigned long cmap_find_batch(const struct cmap *cmap, unsigned long map,
  *       node being deleted may be visited once or not at all.  Other nodes
  *       will be visited once.)
  *
+ *     - If the cmap is changing, it is not safe to quiesce while iterating.
+ *       Even if the changes are done by the same thread that's performing the
+ *       iteration (Corollary: it is not safe to call cmap_remove() and quiesce
+ *       in the loop body).
+ *
  *
  * Example
  * =======