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foobar2000.exe's UPnP Media Renderer component (foo_out_upnp.dll) expects that, if a select() call completes successfully with a non-empty writefds set, any immediately following send() call on a socket in the writefds set never fails with WSAEWOULDBLOCK. On Wine, the Winsock select() and send() implementations both call the Unix poll(2) under the hood to test if I/O is possible on the socket. As it turns out, it's entirely possible that Linux poll() may yield POLLOUT on the first call (by select) but *not* the second (by send), even if no send() call has been made in the meanwhile. On Linux (as of v5.19), a connected (ESTABLISHED) TCP socket that has not been shut down indicates (E)POLLOUT only if the ratio of sk_wmem_queued (the amount of bytes queued in the send buffer) to sk_sndbuf (the size of send buffer size itself, which can be retrieved via SO_SNDBUF) is below a certain threshold. Therefore, a falling edge in POLLOUT can be triggered due to a number of reasons: 1. TCP fragmentation. Once a TCP packet is split out from a larger sk_buff, it incurs extra bookkeeping overhead (e.g. sk_buff header) that is counted in sk_wmem_queued alongside application data. See also: tcp_fragment(), tso_fragment() (Linux 5.19). 2. Control packets (e.g. MTU probing). Such packets share the same buffer with application-initiated packets, and thus counted in sk_wmem_queued. See also: sk_wmem_queued_add() callers (Linux 5.19). 3. Memory pressure. This causes sk_sndbuf to shrink. See also: sk_stream_moderate_sndbuf() callers (Linux 5.19). Fix this by always attempting synchronous I/O first if req->force_async is unset and the nonblocking flag is set. Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=53486 |
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| .. | ||
| async.c | ||
| atom.c | ||
| change.c | ||
| class.c | ||
| clipboard.c | ||
| completion.c | ||
| console.c | ||
| debugger.c | ||
| device.c | ||
| directory.c | ||
| event.c | ||
| fd.c | ||
| file.c | ||
| file.h | ||
| handle.c | ||
| handle.h | ||
| hook.c | ||
| mach.c | ||
| mailslot.c | ||
| main.c | ||
| Makefile.in | ||
| mapping.c | ||
| mutex.c | ||
| named_pipe.c | ||
| object.c | ||
| object.h | ||
| process.c | ||
| process.h | ||
| procfs.c | ||
| protocol.def | ||
| ptrace.c | ||
| queue.c | ||
| region.c | ||
| registry.c | ||
| request.c | ||
| request.h | ||
| security.h | ||
| semaphore.c | ||
| serial.c | ||
| signal.c | ||
| sock.c | ||
| symlink.c | ||
| thread.c | ||
| thread.h | ||
| timer.c | ||
| token.c | ||
| trace.c | ||
| unicode.c | ||
| unicode.h | ||
| user.c | ||
| user.h | ||
| window.c | ||
| wineserver.de.UTF-8.man.in | ||
| wineserver.fr.UTF-8.man.in | ||
| wineserver.man.in | ||
| winstation.c | ||