Commit 8ac5f9e9 authored by Ben Walker's avatar Ben Walker Committed by Tomasz Zawadzki
Browse files

sock/posix: Fix read logic to avoid double-adding socket to pending_recv 



Also write some better comments

Change-Id: I81d59307c5eacc5a71879a83e5040da667909d96
Signed-off-by: default avatarBen Walker <benjamin.walker@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/6745


Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: default avatarJim Harris <james.r.harris@intel.com>
Reviewed-by: default avatarShuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
parent 01aa5cb3

module/sock/posix/posix.c

+14 −2
Original line number Diff line number Diff line
@@ -885,7 +885,9 @@ posix_sock_recv_from_pipe(struct spdk_posix_sock *sock, struct iovec *diov, int 


	spdk_pipe_reader_advance(sock->recv_pipe, bytes);



	/* If we drained the pipe, take it off the level-triggered list */

	/* If we drained the pipe, take it off the pending_recv list. The socket may still have data buffered

	 * in the kernel to receive, but this will be handled on the next poll call when we get the same EPOLLIN

	 * event again. */

	if (sock->base.group_impl && spdk_pipe_reader_bytes_available(sock->recv_pipe) == 0) {

		group = __posix_group_impl(sock->base.group_impl);

		TAILQ_REMOVE(&group->pending_recv, sock, link);
@@ -908,7 +910,17 @@ posix_sock_read(struct spdk_posix_sock *sock) 
		bytes = readv(sock->fd, iov, 2);

		if (bytes > 0) {

			spdk_pipe_writer_advance(sock->recv_pipe, bytes);

			if (sock->base.group_impl) {



			/* For normal operation, this function is called in response to an EPOLLIN

			 * event, which already placed the socket onto the pending_recv list.

			 * But between polls the user may repeatedly call posix_sock_read

			 * and if they clear the pipe on one of those earlier calls, the

			 * socket will be removed from the pending_recv list. In that case,

			 * if we now found more data, put it back on.

			 * This essentially never happens in practice because the application

			 * will stop trying to receive and wait for the next EPOLLIN event, but

			 * for correctness let's handle it. */

			if (!sock->pending_recv && sock->base.group_impl) {

				group = __posix_group_impl(sock->base.group_impl);

				TAILQ_INSERT_TAIL(&group->pending_recv, sock, link);

				sock->pending_recv = true;