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b746af9990
As reported by github user @JB0925 in issue #2427, there is a possible crash in pool_flush(). The problem is that if the free_list is not empty in the first test, and is empty at the moment the xchg() is performed, for example because another thread called it in parallel, we place a POOL_BUSY there that is never removed later, causing the next thread to wait forever. This was introduced in 2.5 with commit 2a4523f6f ("BUG/MAJOR: pools: fix possible race with free() in the lockless variant"). It has probably very rarely been detected, because: - pool_flush() is only called when stopping is set - the function does nothing if global pools are disabled, which is the case on most modern systems with a fast memory allocator. It's possible to reproduce it by modifying __task_free() to call pool_flush() on 1% of the calls instead of only when stopping. The fix is quite simple, it consists in moving the zeroing of the entry in the break path after verifying that the entry was not already busy. This must be backported wherever commit 2a4523f6f is.
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)