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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
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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];
}