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c930a07722
When GDB attaches to a multi-threaded process, it calls linux_proc_attach_tgid_threads () to go through all threads found in /proc/PID/task/ and call attach_proc_task_lwp_callback () on each of them. If it does that twice without the callback reporting that a new thread was found, then it considers that all inferior threads have been found and returns. The problem is that the callback considers any thread that it hasn't attached to yet as new. This causes problems if the process has one or more zombie threads, because GDB can't attach to it and the loop will always "find" a new thread (the zombie one), and get stuck in an infinite loop. This is easy to trigger (at least on aarch64-linux and powerpc64le-linux) with the gdb.threads/attach-many-short-lived-threads.exp testcase, because its test program constantly creates and finishes joinable threads so the chance of having zombie threads is high. This problem causes the following failures: FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 8: attach (timeout) FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 8: no new threads (timeout) FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 8: set breakpoint always-inserted on (timeout) FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 8: break break_fn (timeout) FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 8: break at break_fn: 1 (timeout) FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 8: break at break_fn: 2 (timeout) FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 8: break at break_fn: 3 (timeout) FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 8: reset timer in the inferior (timeout) FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 8: print seconds_left (timeout) FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 8: detach (timeout) FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 8: set breakpoint always-inserted off (timeout) FAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 8: delete all breakpoints, watchpoints, tracepoints, and catchpoints in delete_breakpoints (timeout) ERROR: breakpoints not deleted The iteration number is random, and all tests in the subsequent iterations fail too, because GDB is stuck in the attach command at the beginning of the iteration. The solution is to make linux_proc_attach_tgid_threads () remember when it has already processed a given LWP and skip it in the subsequent iterations. PR testsuite/31312 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31312 Reviewed-By: Luis Machado <luis.machado@arm.com> Approved-By: Pedro Alves <pedro@palves.net>
100 lines
3.6 KiB
C++
100 lines
3.6 KiB
C++
/* Linux-specific PROCFS manipulation routines.
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Copyright (C) 2011-2024 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef NAT_LINUX_PROCFS_H
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#define NAT_LINUX_PROCFS_H
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#include <unistd.h>
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/* Return the TGID of LWPID from /proc/pid/status. Returns -1 if not
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found. Failure to open the /proc file results in a warning. */
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extern int linux_proc_get_tgid (pid_t lwpid);
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/* Return the TracerPid of LWPID from /proc/pid/status. Returns -1 if
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not found. Does not warn on failure to open the /proc file. */
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extern pid_t linux_proc_get_tracerpid_nowarn (pid_t lwpid);
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/* Detect `T (stopped)' in `/proc/PID/status'.
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Other states including `T (tracing stop)' are reported as false. */
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extern int linux_proc_pid_is_stopped (pid_t pid);
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extern int linux_proc_pid_is_trace_stopped_nowarn (pid_t pid);
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/* Return non-zero if PID is a zombie. Failure to open the
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/proc/pid/status file results in a warning. */
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extern int linux_proc_pid_is_zombie (pid_t pid);
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/* Return non-zero if PID is a zombie. Does not warn on failure to
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open the /proc file. */
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extern int linux_proc_pid_is_zombie_nowarn (pid_t pid);
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/* Return non-zero if /proc/PID/status indicates that PID is gone
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(i.e., in Z/Zombie or X/Dead state). Failure to open the /proc
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file is assumed to indicate the thread is gone. */
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extern int linux_proc_pid_is_gone (pid_t pid);
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/* Index of fields of interest in /proc/PID/stat, from procfs(5) man page. */
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#define LINUX_PROC_STAT_STATE 3
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#define LINUX_PROC_STAT_STARTTIME 22
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#define LINUX_PROC_STAT_PROCESSOR 39
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/* Returns FIELD (as numbered in procfs(5) man page) of
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/proc/PID/task/LWP/stat file. */
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extern std::optional<std::string> linux_proc_get_stat_field (ptid_t ptid,
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int field);
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/* Return a string giving the thread's name or NULL if the
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information is unavailable. The returned value points to a statically
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allocated buffer. The value therefore becomes invalid at the next
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linux_proc_tid_get_name call. */
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extern const char *linux_proc_tid_get_name (ptid_t ptid);
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/* Callback function for linux_proc_attach_tgid_threads. If the PTID
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thread is not yet known, try to attach to it and return true,
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otherwise return false. */
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typedef int (*linux_proc_attach_lwp_func) (ptid_t ptid);
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/* If PID is a tgid, scan the /proc/PID/task/ directory for existing
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threads, and call FUNC for each thread found. */
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extern void linux_proc_attach_tgid_threads (pid_t pid,
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linux_proc_attach_lwp_func func);
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/* Return true if the /proc/PID/task/ directory exists. */
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extern int linux_proc_task_list_dir_exists (pid_t pid);
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/* Return the full absolute name of the executable file that was run
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to create the process PID. The returned value persists until this
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function is next called. */
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extern const char *linux_proc_pid_to_exec_file (int pid);
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/* Display possible problems on this system. Display them only once
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per GDB execution. */
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extern void linux_proc_init_warnings ();
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#endif /* NAT_LINUX_PROCFS_H */
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