tools/hv: terminate fcopy daemon if read from uio fails

Terminate endless loop in reading fails, to avoid flooding syslog.

This happens if the state of "Guest services" integration service
is changed from "enabled" to "disabled" at runtime in the VM
settings. In this case pread returns EIO.

Also handle an interrupted system call, and continue in this case.

Signed-off-by: Olaf Hering <[email protected]>
Reviewed-by: Saurabh Sengar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <[email protected]>

Author: olafhering

tools/hv/hv_fcopy_uio_daemon.c

@@ -466,8 +466,10 @@ int main(int argc, char *argv[])
 		 */
 		ret = pread(fcopy_fd, &tmp, sizeof(int), 0);
 		if (ret < 0) {
+			if (errno == EINTR || errno == EAGAIN)
+				continue;
 			syslog(LOG_ERR, "pread failed: %s", strerror(errno));
-			continue;
+			goto close;
 		}
 
 		len = HV_RING_SIZE;