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dde1b4499a
The crash that was fixed by commit 7045590d8 ("BUG/MAJOR: dns: attempt
to lock globaly for msg waiter list instead of use barrier") was now
completely analysed and confirmed to be partially a result of the
debugging code added to LIST_INLIST(), which was looking at both
pointers and their reciprocals, and that, if used in a concurrent
context, could perfectly return false if a neighbor was being added or
removed while the current one didn't change, allowing the LIST_APPEND
to fail.
As the LIST API was not designed to be used in a concurrent context,
we should not rely on LIST_INLIST() but on the newly introduced
LIST_INLIST_ATOMIC().
This patch simply reverts the commit above to switch to the new test,
saving a lock during potentially long operations. It was verified that
the check doesn't fail anymore.
It is unsure what the performance impact of the fix above could be in
some contexts. If any performance regression is observed, it could make
sense to backport this patch, along with the previous commit introducing
the LIST_INLIST_ATOMIC() macro.
The HAProxy documentation has been split into a number of different files for ease of use. Please refer to the following files depending on what you're looking for : - INSTALL for instructions on how to build and install HAProxy - BRANCHES to understand the project's life cycle and what version to use - LICENSE for the project's license - CONTRIBUTING for the process to follow to submit contributions The more detailed documentation is located into the doc/ directory : - doc/intro.txt for a quick introduction on HAProxy - doc/configuration.txt for the configuration's reference manual - doc/lua.txt for the Lua's reference manual - doc/SPOE.txt for how to use the SPOE engine - doc/network-namespaces.txt for how to use network namespaces under Linux - doc/management.txt for the management guide - doc/regression-testing.txt for how to use the regression testing suite - doc/peers.txt for the peers protocol reference - doc/coding-style.txt for how to adopt HAProxy's coding style - doc/internals for developer-specific documentation (not all up to date)