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perf/hw_breakpoint: Simplify breakpoint enable in perf_event_modify_breakpoint

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We can safely enable the breakpoint back for both the fail and success
paths by checking only the bp->attr.disabled, which either holds the new
'requested' disabled state or the original breakpoint state.

Committer testing:

At the end of the series, the 'perf test' entry introduced as the first
patch now runs to completion without finding the fixed issues:

  # perf test "bp modify"
  62: x86 bp modify                                         : Ok
  #

In verbose mode:

  # perf test -v "bp modify"
  62: x86 bp modify                                         :
  --- start ---
  test child forked, pid 5161
  rip 5950a0, bp_1 0x5950a0
  in bp_1
  rip 5950a0, bp_1 0x5950a0
  in bp_1
  test child finished with 0
  ---- end ----
  x86 bp modify: Ok

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Milind Chabbi <chabbi.milind@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180827091228.2878-6-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Jiri Olsa 2018-08-27 11:12:28 +02:00 committed by Arnaldo Carvalho de Melo
parent 969558371b
commit bf06278c3f
1 changed files with 3 additions and 8 deletions
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7
kernel/events/core.c
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@ -2867,18 +2867,13 @@ static int perf_event_modify_breakpoint(struct perf_event *bp,
_perf_event_disable(bp);
err = modify_user_hw_breakpoint_check(bp, attr, true);
if (err) {
if (!bp->attr.disabled)
_perf_event_enable(bp);
return err;
}
if (!attr->disabled)
_perf_event_enable(bp);
return 0;
}
static int perf_event_modify_attr(struct perf_event *event,
struct perf_event_attr *attr)
{