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From: Jiri Olsa <jolsa@kernel.org>
To: Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: lkml <linux-kernel@vger.kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	David Ahern <dsahern@gmail.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Milind Chabbi <chabbi.milind@gmail.com>,
	Oleg Nesterov <oleg@redhat.com>
Subject: [PATCHv4 0/5] perf/hw_breakpoint: Fix breakpoint modify
Date: Mon, 27 Aug 2018 11:12:23 +0200
Message-ID: <20180827091228.2878-1-jolsa@kernel.org> (raw)

hi,
Milind reported that modify_user_hw_breakpoint wouldn't
allow the breakpoint changing if the new attr had 'disabled'
set to true.

I found a case where it actualy prevents ptrace user interface
to change the breakpoint. It's described in patch 1 as perf test,
patch 2 is the breakpoint code fix.

I ran strace tests, nothing (new) broken there..

v4 changes:
  - added Oleg's and Frederic's acks

v3 changes:
  - added Oleg's ack for patch 3
  - new patches 4,5 based on Oleg's suggestions
    replacing the v2 fallback approach by enabling
    the event directly after failed modification

v2 changes:
  - added Oleg's ack for patch 2
  - added new changes based on Oleg's questions
    plus new test code

thanks,
jirka

---
Jiri Olsa (5):
      perf tests: Add breakpoint modify tests
      perf/hw_breakpoint: Modify breakpoint even if the new attr has disabled set
      perf/hw_breakpoint: Remove superfluous bp->attr.disabled = 0
      perf/hw_breakpoint: Enable breakpoint in modify_user_hw_breakpoint
      perf/hw_breakpoint: Simplify breakpoint enable in perf_event_modify_breakpoint

 kernel/events/core.c                     |  11 ++-----
 kernel/events/hw_breakpoint.c            |  13 ++++----
 tools/perf/arch/x86/include/arch-tests.h |   1 +
 tools/perf/arch/x86/tests/Build          |   1 +
 tools/perf/arch/x86/tests/arch-tests.c   |   6 ++++
 tools/perf/arch/x86/tests/bp-modify.c    | 213 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 230 insertions(+), 15 deletions(-)
 create mode 100644 tools/perf/arch/x86/tests/bp-modify.c

             reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-27  9:12 Jiri Olsa [this message]
2018-08-27  9:12 ` [PATCH 1/5] perf tests: Add breakpoint modify tests Jiri Olsa
2018-09-06 13:01   ` [tip:perf/core] " tip-bot for Jiri Olsa
2018-08-27  9:12 ` [PATCH 2/5] perf/hw_breakpoint: Modify breakpoint even if the new attr has disabled set Jiri Olsa
2018-09-06 13:02   ` [tip:perf/core] " tip-bot for Jiri Olsa
2018-08-27  9:12 ` [PATCH 3/5] perf/hw_breakpoint: Remove superfluous bp->attr.disabled = 0 Jiri Olsa
2018-09-06 13:02   ` [tip:perf/core] " tip-bot for Jiri Olsa
2018-08-27  9:12 ` [PATCH 4/5] perf/hw_breakpoint: Enable breakpoint in modify_user_hw_breakpoint Jiri Olsa
2018-09-06 13:03   ` [tip:perf/core] " tip-bot for Jiri Olsa
2018-08-27  9:12 ` [PATCH 5/5] perf/hw_breakpoint: Simplify breakpoint enable in perf_event_modify_breakpoint Jiri Olsa
2018-09-06 13:03   ` [tip:perf/core] " tip-bot for Jiri Olsa
2018-08-30 18:39 ` [PATCHv4 0/5] perf/hw_breakpoint: Fix breakpoint modify Arnaldo Carvalho de Melo

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