Creme: Socket removal notification

Creme is a tiny Linux kernel module that notifies the application of complete socket structure removal in the kernel. This is needed for connection handoff in Prism, to appear in USENIX NSDI 2021.

Compile and Test

make
make test

Usage

1. Open /dev/creme

crfd = open("/dev/creme", O_RDWR);

2. Create an eventfd

evfd = eventfd(0, 0);

3. Register an accepted socket and eventfd with ioctl()

uint64_t val = ((uint64_t)evfd << 32) | newfd /* accepted socket */;
ioctl(crfd, 0, (unsigned long)&val, sizeof(val)))

4. Wait for connection withdrawal

struct pollfd pfds[1];
pfds[0].fd = evfd;
pfds[0].events = POLLIN | POLLERR;
poll(pfds, 1, 500);
if (pfds[0].revents & POLLIN)
	eventfd_read(pfds[0].fd, &cnt);

See server() in test.c for more details.