Re: [net-next v1 13/16] tcp: RX path for devmem TCP

kernel test robot
2023-12-08T15:41:12Z

Hi Mina,

kernel test robot noticed the following build errors:

[auto build test ERROR on net-next/main]

url: https://github.com/intel-lab-lkp/linux/commits/Mina-Almasry/net-page_pool-factor-out-releasing-DMA-from-releasing-the-page/20231208-085531
base: net-next/main
patch link: https://lore.kernel.org/r/20231208005250.2910004-14-almasrymina%40google.com
patch subject: [net-next v1 13/16] tcp: RX path for devmem TCP
config: alpha-defconfig (https://download.01.org/0day-ci/archive/20231208/202312082353.lFKTtexo-lkp@intel.com/config)
compiler: alpha-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231208/202312082353.lFKTtexo-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202312082353.lFKTtexo-lkp@intel.com/

All errors (new ones prefixed by >>):

net/ipv4/tcp.c: In function 'tcp_recvmsg_dmabuf':
>> net/ipv4/tcp.c:2348:57: error: 'SO_DEVMEM_LINEAR' undeclared (first use in this function)
2348 | err = put_cmsg(msg, SOL_SOCKET, SO_DEVMEM_LINEAR,
| ^~~~~~~~~~~~~~~~
net/ipv4/tcp.c:2348:57: note: each undeclared identifier is reported only once for each function it appears in
>> net/ipv4/tcp.c:2411:48: error: 'SO_DEVMEM_DMABUF' undeclared (first use in this function)
2411 | SO_DEVMEM_DMABUF,
| ^~~~~~~~~~~~~~~~

vim +/SO_DEVMEM_LINEAR +2348 net/ipv4/tcp.c

2306
2307 /* On error, returns the -errno. On success, returns number of bytes sent to the
2308 * user. May not consume all of @remaining_len.
2309 */
2310 static int tcp_recvmsg_dmabuf(const struct sock *sk, const struct sk_buff *skb,
2311 unsigned int offset, struct msghdr *msg,
2312 int remaining_len)
2313 {
2314 struct dmabuf_cmsg dmabuf_cmsg = { 0 };
2315 unsigned int start;
2316 int i, copy, n;
2317 int sent = 0;
2318 int err = 0;
2319
2320 do {
2321 start = skb_headlen(skb);
2322
2323 if (!skb->dmabuf) {
2324 err = -ENODEV;
2325 goto out;
2326 }
2327
2328 /* Copy header. */
2329 copy = start - offset;
2330 if (copy > 0) {
2331 copy = min(copy, remaining_len);
2332
2333 n = copy_to_iter(skb->data + offset, copy,
2334 &msg->msg_iter);
2335 if (n != copy) {
2336 err = -EFAULT;
2337 goto out;
2338 }
2339
2340 offset += copy;
2341 remaining_len -= copy;
2342
2343 /* First a dmabuf_cmsg for # bytes copied to user
2344 * buffer.
2345 */
2346 memset(&dmabuf_cmsg, 0, sizeof(dmabuf_cmsg));
2347 dmabuf_cmsg.frag_size = copy;
> 2348 err = put_cmsg(msg, SOL_SOCKET, SO_DEVMEM_LINEAR,
2349 sizeof(dmabuf_cmsg), &dmabuf_cmsg);
2350 if (err || msg->msg_flags & MSG_CTRUNC) {
2351 msg->msg_flags &= ~MSG_CTRUNC;
2352 if (!err)
2353 err = -ETOOSMALL;
2354 goto out;
2355 }
2356
2357 sent += copy;
2358
2359 if (remaining_len == 0)
2360 goto out;
2361 }
2362
2363 /* after that, send information of dmabuf pages through a
2364 * sequence of cmsg
2365 */
2366 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2367 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2368 struct page_pool_iov *ppiov;
2369 u64 frag_offset;
2370 u32 user_token;
2371 int end;
2372
2373 /* skb->dmabuf should indicate that ALL the frags in
2374 * this skb are dmabuf page_pool_iovs. We're checking
2375 * for that flag above, but also check individual frags
2376 * here. If the tcp stack is not setting skb->dmabuf
2377 * correctly, we still don't want to crash here when
2378 * accessing pgmap or priv below.
2379 */
2380 if (!skb_frag_page_pool_iov(frag)) {
2381 net_err_ratelimited("Found non-dmabuf skb with page_pool_iov");
2382 err = -ENODEV;
2383 goto out;
2384 }
2385
2386 ppiov = skb_frag_page_pool_iov(frag);
2387 end = start + skb_frag_size(frag);
2388 copy = end - offset;
2389
2390 if (copy > 0) {
2391 copy = min(copy, remaining_len);
2392
2393 frag_offset = page_pool_iov_virtual_addr(ppiov) +
2394 skb_frag_off(frag) + offset -
2395 start;
2396 dmabuf_cmsg.frag_offset = frag_offset;
2397 dmabuf_cmsg.frag_size = copy;
2398 err = xa_alloc((struct xarray *)&sk->sk_user_pages,
2399 &user_token, frag->bv_page,
2400 xa_limit_31b, GFP_KERNEL);
2401 if (err)
2402 goto out;
2403
2404 dmabuf_cmsg.frag_token = user_token;
2405 dmabuf_cmsg.dmabuf_id = page_pool_iov_binding_id(ppiov);
2406
2407 offset += copy;
2408 remaining_len -= copy;
2409
2410 err = put_cmsg(msg, SOL_SOCKET,
> 2411 SO_DEVMEM_DMABUF,
2412 sizeof(dmabuf_cmsg),
2413 &dmabuf_cmsg);
2414 if (err || msg->msg_flags & MSG_CTRUNC) {
2415 msg->msg_flags &= ~MSG_CTRUNC;
2416 xa_erase((struct xarray *)&sk->sk_user_pages,
2417 user_token);
2418 if (!err)
2419 err = -ETOOSMALL;
2420 goto out;
2421 }
2422
2423 __skb_frag_ref(frag);
2424
2425 sent += copy;
2426
2427 if (remaining_len == 0)
2428 goto out;
2429 }
2430 start = end;
2431 }
2432
2433 if (!remaining_len)
2434 goto out;
2435
2436 /* if remaining_len is not satisfied yet, we need to go to the
2437 * next frag in the frag_list to satisfy remaining_len.
2438 */
2439 skb = skb_shinfo(skb)->frag_list ?: skb->next;
2440
2441 offset = offset - start;
2442 } while (skb);
2443
2444 if (remaining_len) {
2445 err = -EFAULT;
2446 goto out;
2447 }
2448
2449 out:
2450 if (!sent)
2451 sent = err;
2452
2453 return sent;
2454 }
2455

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