tree 7238eafd0aecae71dda723bef8f4912de9c7eccf
parent 285192564d2a7d6eff077d91758b603ba7f2b10a
author Willy Tarreau <w@1wt.eu> 1551348862 +0100
committer Willy Tarreau <w@1wt.eu> 1551365971 +0100
encoding latin1

BUG/MEDIUM: list: add missing store barriers when updating elements and head

Commit a8434ec14 ("MINOR: lists: Implement locked variations.")
introduced locked lists which use the elements pointers as locks
for concurrent operations. Under heavy stress the lists occasionally
fail. The cause is a missing barrier at some points when updating
the list element and the head : nothing prevents the compiler (or
CPU) from updating the list head first before updating the element,
making another thread jump to a wrong location. This patch simply
adds the missing barriers before these two opeations.

This will have to be backported if the commit above is backported.