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From: sergiodj+buildbot@sergiodj.net To: gdb-testers@sourceware.org Subject: [binutils-gdb] [gdb] Handle vfork in thread with follow-fork-mode child Date: Thu, 18 Apr 2019 16:30:00 -0000 [thread overview] Message-ID: <b73715df01e6e9b3de5a49cd7bf4170deef48461@gdb-build> (raw) *** TEST RESULTS FOR COMMIT b73715df01e6e9b3de5a49cd7bf4170deef48461 *** Author: Tom de Vries <tdevries@suse.de> Branch: master Commit: b73715df01e6e9b3de5a49cd7bf4170deef48461 [gdb] Handle vfork in thread with follow-fork-mode child When debugging any of the testcases added by this commit, which do a vfork in a thread with "set follow-fork-mode child" + "set detach-on-fork on", we run into this assertion: ... src/gdb/nat/x86-linux-dregs.c:146: internal-error: \ void x86_linux_update_debug_registers(lwp_info*): \ Assertion `lwp_is_stopped (lwp)' failed. ... The assert is caused by the following: the vfork-child exit or exec event is handled by handle_vfork_child_exec_or_exit, which calls target_detach to detach from the vfork parent. During target_detach we call linux_nat_target::detach, which: #1 - stops all the threads #2 - waits for all the threads to be stopped #3 - detaches all the threads However, during the second step we run into this code in stop_wait_callback: ... /* If this is a vfork parent, bail out, it is not going to report any SIGSTOP until the vfork is done with. */ if (inf->vfork_child != NULL) return 0; ... and we don't wait for the threads to be stopped, which results in this assert in x86_linux_update_debug_registers triggering during the third step: ... gdb_assert (lwp_is_stopped (lwp)); ... The fix is to reset the vfork parent's vfork_child field before calling target_detach in handle_vfork_child_exec_or_exit. There's already similar code for the other paths handled by handle_vfork_child_exec_or_exit, so this commit refactors the code a bit so that all paths share the same code. The new tests cover both a vfork child exiting, and a vfork child execing, since both cases would trigger the assertion. The new testcases also exercise following the vfork children with "set detach-on-fork off", since it doesn't seem to be tested anywhere. Tested on x86_64-linux, using native and native-gdbserver. gdb/ChangeLog: 2019-04-18 Tom de Vries <tdevries@suse.de> Pedro Alves <palves@redhat.com> PR gdb/24454 * infrun.c (handle_vfork_child_exec_or_exit): Reset vfork parent's vfork_child field before calling target_detach. gdb/testsuite/ChangeLog: 2019-04-18 Tom de Vries <tdevries@suse.de> Pedro Alves <palves@redhat.com> PR gdb/24454 * gdb.threads/vfork-follow-child-exec.c: New file. * gdb.threads/vfork-follow-child-exec.exp: New file. * gdb.threads/vfork-follow-child-exit.c: New file. * gdb.threads/vfork-follow-child-exit.exp: New file.
next reply other threads:[~2019-04-18 16:30 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-04-18 16:30 sergiodj+buildbot [this message] 2019-04-18 16:52 ` Failures on RHEL-s390x-m64, branch master sergiodj+buildbot 2019-04-18 18:03 ` Failures on Debian-s390x-native-gdbserver-m64, " sergiodj+buildbot 2019-04-18 18:04 ` Failures on Debian-s390x-m64, " sergiodj+buildbot 2019-04-23 9:06 ` Failures on Fedora-x86_64-native-gdbserver-m64, " sergiodj+buildbot 2019-04-23 9:10 ` Failures on Fedora-x86_64-m64, " sergiodj+buildbot 2019-04-23 9:42 ` Failures on Fedora-x86_64-native-gdbserver-m32, " sergiodj+buildbot 2019-04-24 3:12 ` Failures on Fedora-x86_64-cc-with-index, " sergiodj+buildbot 2019-04-26 23:21 ` Failures on Fedora-x86_64-native-extended-gdbserver-m32, " sergiodj+buildbot 2019-05-01 1:57 ` Failures on Fedora-x86_64-m32, " sergiodj+buildbot
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