lkml.org 
[lkml]   [2022]   [Aug]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.19 0973/1157] perf tools: Fix dso_id inode generation comparison
    Date
    From: Adrian Hunter <adrian.hunter@intel.com>

    [ Upstream commit 68566a7cf56bf3148797c218ed45a9de078ef47c ]

    Synthesized MMAP events have zero ino_generation, so do not compare
    them to DSOs with a real ino_generation otherwise we end up with a DSO
    without a build id.

    Fixes: 0e3149f86b99ddab ("perf dso: Move dso_id from 'struct map' to 'struct dso'")
    Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
    Cc: Andi Kleen <ak@linux.intel.com>
    Cc: Ian Rogers <irogers@google.com>
    Cc: Jiri Olsa <jolsa@kernel.org>
    Cc: kvm@vger.kernel.org
    Cc: Namhyung Kim <namhyung@kernel.org>
    Link: https://lore.kernel.org/r/20220711093218.10967-2-adrian.hunter@intel.com
    [ Added clarification to the comment from Ian + more detailed explanation from Adrian ]
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    tools/perf/util/dsos.c | 15 +++++++++++++--
    1 file changed, 13 insertions(+), 2 deletions(-)

    diff --git a/tools/perf/util/dsos.c b/tools/perf/util/dsos.c
    index b97366f77bbf..2bd23e4cf19e 100644
    --- a/tools/perf/util/dsos.c
    +++ b/tools/perf/util/dsos.c
    @@ -23,8 +23,19 @@ static int __dso_id__cmp(struct dso_id *a, struct dso_id *b)
    if (a->ino > b->ino) return -1;
    if (a->ino < b->ino) return 1;

    - if (a->ino_generation > b->ino_generation) return -1;
    - if (a->ino_generation < b->ino_generation) return 1;
    + /*
    + * Synthesized MMAP events have zero ino_generation, avoid comparing
    + * them with MMAP events with actual ino_generation.
    + *
    + * I found it harmful because the mismatch resulted in a new
    + * dso that did not have a build ID whereas the original dso did have a
    + * build ID. The build ID was essential because the object was not found
    + * otherwise. - Adrian
    + */
    + if (a->ino_generation && b->ino_generation) {
    + if (a->ino_generation > b->ino_generation) return -1;
    + if (a->ino_generation < b->ino_generation) return 1;
    + }

    return 0;
    }
    --
    2.35.1


    \
     
     \ /
      Last update: 2022-08-16 06:49    [W:4.414 / U:0.032 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site