fa6af9b25e
If PinLocalBuffer() were to modify the buf_state, the buf_state in GetLocalVictimBuffer() would be out of date. Currently that does not happen, as PinLocalBuffer() only modifies the buf_state if adjust_usagecount=true and GetLocalVictimBuffer() passes false. However, it's easy to make this not the case anymore - it cost me a few hours to debug the consequences. The minimal fix would be to just refetch the buf_state after after calling PinLocalBuffer(), but the same danger exists in later parts of the function. Instead, declare buf_state in the narrower scopes and re-read the state in conditional branches. Besides being safer, it also fits well with an upcoming set of cleanup patches that move the contents of the conditional branches in GetLocalVictimBuffer() into helper functions. I "broke" this in 794f2594479. Arguably this should be backpatched, but as the relevant functions are not exported and there is no actual misbehaviour, I chose to not backpatch, at least for now. Reviewed-by: Melanie Plageman <melanieplageman@gmail.com> Discussion: https://postgr.es/m/CAAKRu_b9anbWzEs5AAF9WCvcEVmgz-1AkHSQ-CLLy-p7WHzvFw@mail.gmail.com
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.