[PATCH 5.10.y 0/2] Fixed perf abort when taken branch stack sampling enabled

[Shuai Xue]

On x86 platform, kernel v5.10.228, perf-report command aborts due to "free():
invalid pointer" when perf-record command is run with taken branch stack
sampling enabled. This regression can be reproduced with the following steps:

	- sudo perf record -b
	- sudo perf report

The root cause is that bi[i].to.ms.maps does not always point to thread->maps,
which is a buffer dynamically allocated by maps_new(). Instead, it may point to
&machine->kmaps, while kmaps is not a pointer but a variable. The original
upstream commit c1149037f65b ("perf hist: Add missing puts to
hist__account_cycles") worked well because machine->kmaps had been refactored to
a pointer by the previous commit 1a97cee604dc ("perf maps: Use a pointer for
kmaps").

The memory leak issue, which the reverted patch intended to fix, has been solved
by commit cf96b8e45a9b ("perf session: Add missing evlist__delete when deleting
a session"). The root cause is that the evlist is not being deleted on exit in
perf-report, perf-script, and perf-data. Consequently, the reference count of
the thread increased by thread__get() in hist_entry__init() is not decremented
in hist_entry__delete(). As a result, thread->maps is not properly freed.

To this end,

- PATCH 1/2 reverts commit a83fc293acd5c5050a4828eced4a71d2b2fffdd3 to fix the
  abort regression.
- PATCH 2/2 backports cf96b8e45a9b ("perf session: Add missing evlist__delete
  when deleting a session") to fix memory leak issue.

Riccardo Mancini (1):
  perf session: Add missing evlist__delete when deleting a session

Shuai Xue (1):
  Revert "perf hist: Add missing puts to hist__account_cycles"

 tools/perf/util/hist.c    | 10 +++-------
 tools/perf/util/session.c |  5 ++++-
 2 files changed, 7 insertions(+), 8 deletions(-)

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2.39.3