175 lines
4.5 KiB
Diff
175 lines
4.5 KiB
Diff
http://sourceware.org/ml/gdb-patches/2012-04/msg00058.html
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Subject: [downstream patch FYI] workaround stale frame_info * (PR 13866)
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Hi,
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I did not look at which commit caused this regression but apparently it was
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introduced at least with multi-inferiors.
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I understand this fix is not right fix of the crash; but in most GDB cases one
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does not use multi-inferior so why to regress single-inferior by it.
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Some more simple solutions still fix the single-inferior mode but they
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regressed the multi-inferior mode
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gdb.threads/no-unwaited-for-left.exp
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gdb.multi/base.exp
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so I had to put there that sorting magic.
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With proper C++ sanity check of stale live frame_info references the testcase
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would be simple without the "frame_garbage_collection" reproducer below.
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It is also reproducible just with valgrind but regularly running the whole
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testsuite under valgrind I did not find feasible.
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No regressions on {x86_64,x86_64-m32,i686}-fedora17-linux-gnu.
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Thanks,
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Jan
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gdb/
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2012-04-04 Jan Kratochvil <jan.kratochvil@redhat.com>
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Workaround PR backtrace/13866.
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* progspace.c (switch_to_program_space_and_thread): Try not to call
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switch_to_thread.
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--- a/gdb/progspace.c
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+++ b/gdb/progspace.c
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@@ -481,17 +481,28 @@ save_current_space_and_thread (void)
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void
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switch_to_program_space_and_thread (struct program_space *pspace)
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{
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- struct inferior *inf;
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+ struct inferior *inf = current_inferior ();
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- inf = find_inferior_for_program_space (pspace);
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+ if (inf->pspace != pspace)
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+ inf = find_inferior_for_program_space (pspace);
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if (inf != NULL && inf->pid != 0)
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{
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- struct thread_info *tp;
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+ struct thread_info *tp, *current_tp = NULL;
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+
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+ if (ptid_get_pid (inferior_ptid) == inf->pid)
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+ current_tp = find_thread_ptid (inferior_ptid);
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tp = any_live_thread_of_process (inf->pid);
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if (tp != NULL)
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{
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- switch_to_thread (tp->ptid);
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+ /* Prefer primarily thread not THREAD_EXITED and secondarily thread
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+ not EXECUTING. */
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+ if (current_tp == NULL
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+ || (tp->state != THREAD_EXITED
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+ && current_tp->state == THREAD_EXITED)
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+ || (!tp->executing && current_tp->executing))
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+ switch_to_thread (tp->ptid);
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+
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/* Switching thread switches pspace implicitly. We're
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done. */
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return;
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Reproducer with:
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./gdb -nx ~/t/thread -ex 'b 24' -ex r -ex 'until 25'
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Breakpoint 1, main () at /home/jkratoch/t/thread.c:24
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24 v++;
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Segmentation fault (core dumped)
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#include <pthread.h>
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#include <assert.h>
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#include <unistd.h>
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static int v;
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static void *start (void *arg)
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{
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v++;
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v++;
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v++;
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v++;
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sleep (100);
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return arg;
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}
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int main (void)
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{
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pthread_t thread1;
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int i;
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i = pthread_create (&thread1, NULL, start, NULL);
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assert (i == 0);
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v++;
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v++;
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v++;
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v++;
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i = pthread_join (thread1, NULL);
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assert (i == 0);
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return 0;
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}
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### --- a/gdb/frame.c
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### +++ b/gdb/frame.c
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### @@ -1522,12 +1522,30 @@ frame_observer_target_changed (struct target_ops *target)
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### reinit_frame_cache ();
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### }
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###
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### +typedef struct obstack obstack_s;
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### +DEF_VEC_O (obstack_s);
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### +static VEC (obstack_s) *frame_poison_vec;
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### +
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### +void frame_garbage_collection (void);
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### +void
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### +frame_garbage_collection (void)
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### +{
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### + struct obstack *obstack_p;
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### + int ix;
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### +
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### + for (ix = 0; VEC_iterate (obstack_s, frame_poison_vec, ix, obstack_p); ix++)
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### + obstack_free (obstack_p, 0);
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### +
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### + VEC_free (obstack_s, frame_poison_vec);
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### + frame_poison_vec = NULL;
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### +}
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### +
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### /* Flush the entire frame cache. */
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###
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### void
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### reinit_frame_cache (void)
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### {
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### - struct frame_info *fi;
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### + struct frame_info *fi, *fi_prev;
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###
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### /* Tear down all frame caches. */
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### for (fi = current_frame; fi != NULL; fi = fi->prev)
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### @@ -1538,8 +1556,14 @@ reinit_frame_cache (void)
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### fi->base->unwind->dealloc_cache (fi, fi->base_cache);
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### }
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###
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### + for (fi = current_frame; fi != NULL; fi = fi_prev)
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### + {
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### + fi_prev = fi->prev;
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### + memset (fi, 0, sizeof (*fi));
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### + }
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### + VEC_safe_push (obstack_s, frame_poison_vec, &frame_cache_obstack);
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### +
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### /* Since we can't really be sure what the first object allocated was. */
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### - obstack_free (&frame_cache_obstack, 0);
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### obstack_init (&frame_cache_obstack);
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###
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### if (current_frame != NULL)
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### --- a/gdb/top.c
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### +++ b/gdb/top.c
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### @@ -359,6 +359,11 @@ prepare_execute_command (void)
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### if (non_stop)
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### target_dcache_invalidate ();
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###
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### + {
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### + extern void frame_garbage_collection (void);
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### + frame_garbage_collection ();
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### + }
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### +
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### return cleanup;
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### }
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###
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