qemu-progress: Fix progress printing on SIGUSR1

Since commit a7aae221 ('Switch SIG_IPI to SIGUSR1'), SIGUSR1 is blocked
during startup, breaking the progress report in tools.

This patch reenables the signal when initialising a progress report.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NBenoit Canet <benoit@irqsave.net>

util/qemu-progress.c

@@ -82,12 +82,22 @@ static void progress_dummy_init(void)
 {
 #ifdef CONFIG_POSIX
     struct sigaction action;
+    sigset_t set;
 
     memset(&action, 0, sizeof(action));
     sigfillset(&action.sa_mask);
     action.sa_handler = sigusr_print;
     action.sa_flags = 0;
     sigaction(SIGUSR1, &action, NULL);
+
+    /*
+     * SIGUSR1 is SIG_IPI and gets blocked in qemu_init_main_loop(). In the
+     * tools that use the progress report SIGUSR1 isn't used in this meaning
+     * and instead should print the progress, so reenable it.
+     */
+    sigemptyset(&set);
+    sigaddset(&set, SIGUSR1);
+    pthread_sigmask(SIG_UNBLOCK, &set, NULL);
 #endif
 
     state.print = progress_dummy_print;