sleep 5 seconds and log a message if the signalfd(2) fd returns 0

[md@Linux.IT (Marco d'Itri)]

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This is better than just failing because it is quite annoying for the
admin when udevd fails to start while it is being upgraded and breaks
the system.

-- 
ciao,
Marco

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Sleep 5 seconds and log a message if the signalfd(2) fd returns 0.

Users running 2.6.22 kernels reported udevd spinning in a loop with the
signalfd fd reported as readable but providing no data.
See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=551743 for details.

--- a/udev/udevd.c
+++ b/udev/udevd.c
@@ -1076,6 +1076,10 @@ int main(int argc, char *argv[])
 			size = read(pfd[FD_SIGNAL].fd, &fdsi, sizeof(struct signalfd_siginfo));
 			if (size == sizeof(struct signalfd_siginfo))
 				handle_signal(udev, fdsi.ssi_signo);
+			else {
+				err(udev, "read(2) on the signalfd(2) fd returned 0: your kernel is buggy!\n");
+				sleep(5);
+			}
 		}
 
 		/* device node and rules directory inotify watch */