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[gdb/threads] Fix lin_thread_get_thread_signals for glibc 2.28

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When running test-case gdb.threads/create-fail.exp on openSUSE Factory
(with glibc version 2.32) I run into:
...
(gdb) continue
Continuing.
[New Thread 0x7ffff7c83700 (LWP 626354)]
[New Thread 0x7ffff7482700 (LWP 626355)]
[Thread 0x7ffff7c83700 (LWP 626354) exited]
[New Thread 0x7ffff6c81700 (LWP 626356)]
[Thread 0x7ffff7482700 (LWP 626355) exited]
[New Thread 0x7ffff6480700 (LWP 626357)]
[Thread 0x7ffff6c81700 (LWP 626356) exited]
[New Thread 0x7ffff5c7f700 (LWP 626358)]
[Thread 0x7ffff6480700 (LWP 626357) exited]
pthread_create: 22: Invalid argument

Thread 6 "create-fail" received signal SIG32, Real-time event 32.
[Switching to Thread 0x7ffff5c7f700 (LWP 626358)]
0x00007ffff7d87695 in clone () from /lib64/libc.so.6
(gdb) FAIL: gdb.threads/create-fail.exp: iteration 1: run till end
...
The problem is that glibc-internal signal SIGCANCEL is not recognized by gdb.

There's code in check_thread_signals that is supposed to take care of that,
but it's not working because this code in lin_thread_get_thread_signals has
stopped working:
...
  /* NPTL reserves the first two RT signals, but does not provide any
     way for the debugger to query the signal numbers - fortunately
     they don't change.  */
  sigaddset (set, __SIGRTMIN);
  sigaddset (set, __SIGRTMIN + 1);
...

Since glibc commit d2dc5467c6 "Filter out NPTL internal signals (BZ #22391)"
(first released as part of glibc 2.28), a sigaddset with a glibc-internal
signal has no other effect than setting errno to EINVALID.

Fix this by eliminating the usage of sigset_t in check_thread_signals and
lin_thread_get_thread_signals.

The same problem was observed on Ubuntu 20.04.

Tested on x86_64-linux, openSUSE Factory.
Tested on aarch64-linux, Ubuntu 20.04 and Ubuntu 18.04.

gdb/ChangeLog:

2021-02-12  Tom de Vries  <tdevries@suse.de>

	PR threads/26228
	* linux-nat.c (lin_thread_get_thread_signals): Remove.
	(lin_thread_signals): New static var.
	(lin_thread_get_thread_signal_num, lin_thread_get_thread_signal):
	New function.
	* linux-nat.h (lin_thread_get_thread_signals): Remove.
	(lin_thread_get_thread_signal_num, lin_thread_get_thread_signal):
	Declare.
	* linux-thread-db.c (check_thread_signals): Use
	lin_thread_get_thread_signal_num and lin_thread_get_thread_signal.
This commit is contained in:
Tom de Vries 2021-02-12 20:12:37 +01:00
parent c054dcd552
commit 089436f787
4 changed files with 41 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
gdb/ChangeLog
View File

@ -1,3 +1,16 @@
2021-02-12 Tom de Vries <tdevries@suse.de>
PR threads/26228
* linux-nat.c (lin_thread_get_thread_signals): Remove.
(lin_thread_signals): New static var.
(lin_thread_get_thread_signal_num, lin_thread_get_thread_signal):
New function.
* linux-nat.h (lin_thread_get_thread_signals): Remove.
(lin_thread_get_thread_signal_num, lin_thread_get_thread_signal):
Declare.
* linux-thread-db.c (check_thread_signals): Use
lin_thread_get_thread_signal_num and lin_thread_get_thread_signal.
2021-02-12 Andrew Burgess <andrew.burgess@embecosm.com>
* f-exp.y (f77_keywords): Add allocated.

28
gdb/linux-nat.c
View File

@ -4411,16 +4411,24 @@ Enables printf debugging output."),
the GNU/Linux Threads library and therefore doesn't really belong
here. */
/* Return the set of signals used by the threads library in *SET. */
/* NPTL reserves the first two RT signals, but does not provide any
way for the debugger to query the signal numbers - fortunately
they don't change. */
static int lin_thread_signals[] = { __SIGRTMIN, __SIGRTMIN + 1 };
void
lin_thread_get_thread_signals (sigset_t *set)
/* See linux-nat.h. */
unsigned int
lin_thread_get_thread_signal_num (void)
{
sigemptyset (set);
/* NPTL reserves the first two RT signals, but does not provide any
way for the debugger to query the signal numbers - fortunately
they don't change. */
sigaddset (set, __SIGRTMIN);
sigaddset (set, __SIGRTMIN + 1);
return sizeof (lin_thread_signals) / sizeof (lin_thread_signals[0]);
}
/* See linux-nat.h. */
int
lin_thread_get_thread_signal (unsigned int i)
{
gdb_assert (i < lin_thread_get_thread_signal_num ());
return lin_thread_signals[i];
}

7
gdb/linux-nat.h
View File

@ -304,8 +304,11 @@ void check_for_thread_db (void);
true on success, false if the process isn't using libpthread. */
extern int thread_db_notice_clone (ptid_t parent, ptid_t child);
/* Return the set of signals used by the threads library. */
extern void lin_thread_get_thread_signals (sigset_t *mask);
/* Return the number of signals used by the threads library. */
extern unsigned int lin_thread_get_thread_signal_num (void);
/* Return the i-th signal used by the threads library. */
extern int lin_thread_get_thread_signal (unsigned int i);
/* Find process PID's pending signal set from /proc/pid/status. */
void linux_proc_pending_signals (int pid, sigset_t *pending,

21
gdb/linux-thread-db.c
View File

@ -161,8 +161,6 @@ static thread_db_target the_thread_db_target;
/* Non-zero if we have determined the signals used by the threads
library. */
static int thread_signals;
static sigset_t thread_stop_set;
static sigset_t thread_print_set;
struct thread_db_info
{
@ -1225,23 +1223,14 @@ check_thread_signals (void)
{
if (!thread_signals)
{
sigset_t mask;
int i;
lin_thread_get_thread_signals (&mask);
sigemptyset (&thread_stop_set);
sigemptyset (&thread_print_set);
for (i = 1; i < NSIG; i++)
for (i = 0; i < lin_thread_get_thread_signal_num (); i++)
{
if (sigismember (&mask, i))
{
if (signal_stop_update (gdb_signal_from_host (i), 0))
sigaddset (&thread_stop_set, i);
if (signal_print_update (gdb_signal_from_host (i), 0))
sigaddset (&thread_print_set, i);
thread_signals = 1;
}
int sig = lin_thread_get_thread_signal (i);
signal_stop_update (gdb_signal_from_host (sig), 0);
signal_print_update (gdb_signal_from_host (sig), 0);
thread_signals = 1;
}
}
}