[PATCH RFC v1 0/4] perf: Introduce extended syscall error reporting

[Alexander Shishkin <alexander.shishkin@linux.intel.com>]

Hi Peter and Ingo and everybody,

Here's my second stab at improving perf's error reporting by attaching
arbitrary strings to the integer error codes. This is largely based
off of the previous email thread [1].

This time around, I employed a linker trick to convert the structures
containing extended error information into integers, which are then
made to look just like normal error codes so that IS_ERR_VALUE() and
friends would still work correctly on them. So no extra pointers in
the struct perf_event or anywhere else; the extended error codes are
passed around like normal error codes. They only need to be converted
in syscalls' topmost return statements. This is done in 1/4.

Then, 2/4 illustrates how error sites can be extended to include more
information such as file names and line numbers [1].

The other two patches add perf_err() annotation to a few semi-randomly
picked places in perf core (3/4) and x86 bits (4/4).

[1] http://marc.info/?l=linux-kernel&m=141470811013082
[2] http://marc.info/?l=linux-kernel&m=141471816115946

Alexander Shishkin (4):
  perf: Introduce extended syscall error reporting
  perf: Add file name and line number to perf extended error reports
  perf: Annotate some of the error codes with perf_err()
  perf/x86: Annotate some of the error codes with perf_err()

 arch/x86/kernel/cpu/perf_event.c           |   8 ++-
 arch/x86/kernel/cpu/perf_event_intel_lbr.c |   2 +-
 include/linux/perf_event.h                 |  87 +++++++++++++++++++++++
 include/uapi/linux/perf_event.h            |   8 ++-
 kernel/events/core.c                       | 108 +++++++++++++++++++++++++----
 5 files changed, 195 insertions(+), 18 deletions(-)

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2.1.4