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pmu__find_core_pmu() more logically belongs in pmus.c because it iterates over all PMUs, so move it to pmus.c At the same time rename it to perf_pmus__find_core_pmu() to match the naming convention in this file. list_prepare_entry() can't be used in perf_pmus__scan_core() anymore now that it's called from the same compilation unit. This is with -O2 (specifically -O1 -ftree-vrp -finline-functions -finline-small-functions) which allow the bounds of the array access to be determined at compile time. list_prepare_entry() subtracts the offset of the 'list' member in struct perf_pmu from &core_pmus, which isn't a struct perf_pmu. The compiler sees that pmu results in &core_pmus - 8 and refuses to compile. At runtime this works because list_for_each_entry_continue() always adds the offset back again before dereferencing ->next, but it's technically undefined behavior. With -fsanitize=undefined an additional warning is generated. Using list_first_entry_or_null() to get the first entry here avoids doing &core_pmus - 8 but has the same result and fixes both the compile warning and the undefined behavior warning. There are other uses of list_prepare_entry() in pmus.c, but the compiler doesn't seem to be able to see that they can also be called with &core_pmus, so I won't change any at this time. Signed-off-by: James Clark <james.clark@arm.com> Reviewed-by: Ian Rogers <irogers@google.com> Reviewed-by: John Garry <john.g.garry@oracle.com> Cc: Ravi Bangoria <ravi.bangoria@amd.com> Cc: Eduard Zingerman <eddyz87@gmail.com> Cc: Will Deacon <will@kernel.org> Cc: Leo Yan <leo.yan@linaro.org> Cc: Mike Leach <mike.leach@linaro.org> Cc: Jing Zhang <renyu.zj@linux.alibaba.com> Cc: Haixin Yu <yuhaixin.yhx@linux.alibaba.com> Cc: Kan Liang <kan.liang@linux.intel.com> Cc: linux-arm-kernel@lists.infradead.org Link: https://lore.kernel.org/r/20230913153355.138331-2-james.clark@arm.com Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.