rseq/selftests: Fix: Namespace gettid() for compatibility with glibc 2.30

glibc 2.30 introduces gettid() in public headers, which clashes with
the internal static definition within rseq selftests.

Rename gettid() to rseq_gettid() to eliminate this symbol name clash.
Reported-by: Tommi T. Rantala <tommi.t.rantala@nokia.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Tommi T. Rantala <tommi.t.rantala@nokia.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: "Paul E. McKenney" <paulmck@linux.ibm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Paul Turner <pjt@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>	# v4.18+
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/rseq/param_test.c

@@ -15,7 +15,7 @@
 #include <errno.h>
 #include <stddef.h>
 
-static inline pid_t gettid(void)
+static inline pid_t rseq_gettid(void)
 {
 	return syscall(__NR_gettid);
 }
@@ -373,11 +373,12 @@ void *test_percpu_spinlock_thread(void *arg)
 		rseq_percpu_unlock(&data->lock, cpu);
 #ifndef BENCHMARK
 		if (i != 0 && !(i % (reps / 10)))
-			printf_verbose("tid %d: count %lld\n", (int) gettid(), i);
+			printf_verbose("tid %d: count %lld\n",
+				       (int) rseq_gettid(), i);
 #endif
 	}
 	printf_verbose("tid %d: number of rseq abort: %d, signals delivered: %u\n",
-		       (int) gettid(), nr_abort, signals_delivered);
+		       (int) rseq_gettid(), nr_abort, signals_delivered);
 	if (!opt_disable_rseq && thread_data->reg &&
 	    rseq_unregister_current_thread())
 		abort();
@@ -454,11 +455,12 @@ void *test_percpu_inc_thread(void *arg)
 		} while (rseq_unlikely(ret));
 #ifndef BENCHMARK
 		if (i != 0 && !(i % (reps / 10)))
-			printf_verbose("tid %d: count %lld\n", (int) gettid(), i);
+			printf_verbose("tid %d: count %lld\n",
+				       (int) rseq_gettid(), i);
 #endif
 	}
 	printf_verbose("tid %d: number of rseq abort: %d, signals delivered: %u\n",
-		       (int) gettid(), nr_abort, signals_delivered);
+		       (int) rseq_gettid(), nr_abort, signals_delivered);
 	if (!opt_disable_rseq && thread_data->reg &&
 	    rseq_unregister_current_thread())
 		abort();
@@ -605,7 +607,7 @@ void *test_percpu_list_thread(void *arg)
 	}
 
 	printf_verbose("tid %d: number of rseq abort: %d, signals delivered: %u\n",
-		       (int) gettid(), nr_abort, signals_delivered);
+		       (int) rseq_gettid(), nr_abort, signals_delivered);
 	if (!opt_disable_rseq && rseq_unregister_current_thread())
 		abort();
 
@@ -796,7 +798,7 @@ void *test_percpu_buffer_thread(void *arg)
 	}
 
 	printf_verbose("tid %d: number of rseq abort: %d, signals delivered: %u\n",
-		       (int) gettid(), nr_abort, signals_delivered);
+		       (int) rseq_gettid(), nr_abort, signals_delivered);
 	if (!opt_disable_rseq && rseq_unregister_current_thread())
 		abort();
 
@@ -1011,7 +1013,7 @@ void *test_percpu_memcpy_buffer_thread(void *arg)
 	}
 
 	printf_verbose("tid %d: number of rseq abort: %d, signals delivered: %u\n",
-		       (int) gettid(), nr_abort, signals_delivered);
+		       (int) rseq_gettid(), nr_abort, signals_delivered);
 	if (!opt_disable_rseq && rseq_unregister_current_thread())
 		abort();