Blame SOURCES/satyr-0.13-better-inf-recursion-handling.patch

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From 9639948f3fdda4afcf25e7080aa87d8ad2fbeb34 Mon Sep 17 00:00:00 2001
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From: Martin Milata <mmilata@redhat.com>
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Date: Wed, 27 Aug 2014 13:55:50 +0200
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Subject: [SATYR PATCH] Better handling of infinite recursion
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unwind: Append threads/frames in O(1)
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unwind: throw away the most recent frames
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unwind: lower stacktrace length limit to 256
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Fixes #179.
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Signed-off-by: Martin Milata <mmilata@redhat.com>
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---
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 lib/core_unwind_elfutils.c | 36 ++++++++++++++++++++----------------
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 1 file changed, 20 insertions(+), 16 deletions(-)
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diff --git a/lib/core_unwind_elfutils.c b/lib/core_unwind_elfutils.c
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index 43d66be..bbd4813 100644
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--- a/lib/core_unwind_elfutils.c
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+++ b/lib/core_unwind_elfutils.c
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@@ -29,18 +29,18 @@
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 #include <stdio.h>
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 #include <string.h>
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-#define FRAME_LIMIT 1024
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+#define FRAME_LIMIT 256
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 struct frame_callback_arg
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 {
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-    struct sr_core_thread *thread;
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+    struct sr_core_frame **frames_tail;
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     char *error_msg;
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     unsigned nframes;
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 };
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 struct thread_callback_arg
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 {
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-    struct sr_core_stacktrace *stacktrace;
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+    struct sr_core_thread **threads_tail;
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     char *error_msg;
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 };
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@@ -70,15 +70,9 @@ frame_callback(Dwfl_Frame *frame, void *data)
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         return CB_STOP_UNWIND;
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     }
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-    frame_arg->thread->frames =
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-        sr_core_frame_append(frame_arg->thread->frames, result);
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-
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-    /* Avoid huge stacktraces from programs stuck in infinite recursion. */
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+    *frame_arg->frames_tail = result;
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+    frame_arg->frames_tail = &result->next;
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     frame_arg->nframes++;
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-    if (frame_arg->nframes >= FRAME_LIMIT)
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-    {
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-        return CB_STOP_UNWIND;
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-    }
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     return DWARF_CB_OK;
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 }
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@@ -99,7 +93,7 @@ unwind_thread(Dwfl_Thread *thread, void *data)
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     struct frame_callback_arg frame_arg =
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     {
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-        .thread = result,
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+        .frames_tail = &(result->frames),
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         .error_msg = NULL,
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         .nframes = 0
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     };
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@@ -121,14 +115,24 @@ unwind_thread(Dwfl_Thread *thread, void *data)
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         goto abort;
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     }
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-    if (!error_msg && !frame_arg.thread->frames)
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+    if (!error_msg && !result->frames)
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     {
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         set_error("No frames found for thread id %d", (int)result->id);
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         goto abort;
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     }
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-    thread_arg->stacktrace->threads =
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-        sr_core_thread_append(thread_arg->stacktrace->threads, result);
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+    /* Truncate the stacktrace to FRAME_LIMIT least recent frames. */
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+    while (result->frames && frame_arg.nframes > FRAME_LIMIT)
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+    {
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+        struct sr_core_frame *old_frame = result->frames;
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+        result->frames = old_frame->next;
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+        sr_core_frame_free(old_frame);
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+        frame_arg.nframes--;
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+    }
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+
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+    *thread_arg->threads_tail = result;
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+    thread_arg->threads_tail = &result->next;
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+
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     return DWARF_CB_OK;
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 abort:
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@@ -166,7 +170,7 @@ sr_parse_coredump(const char *core_file,
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     struct thread_callback_arg thread_arg =
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     {
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-        .stacktrace = stacktrace,
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+        .threads_tail = &(stacktrace->threads),
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         .error_msg = NULL
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     };
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-- 
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1.9.3
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