From 4550459a8e915a74dfbeb97ab4b645f72165079c Mon Sep 17 00:00:00 2001 From: "Daniel P. Berrange" Date: Wed, 20 Dec 2017 17:56:58 +0100 Subject: [PATCH 18/42] io: get rid of bounce buffering in websock write path RH-Author: Daniel P. Berrange Message-id: <20171220175702.29663-17-berrange@redhat.com> Patchwork-id: 78469 O-Subject: [RHV-7.5 qemu-kvm-rhev PATCH v2 16/20] io: get rid of bounce buffering in websock write path Bugzilla: 1518649 RH-Acked-by: John Snow RH-Acked-by: Jeffrey Cody RH-Acked-by: Miroslav Rezanina Currently most outbound I/O on the websock channel gets copied into the rawoutput buffer, and then immediately copied again into the encoutput buffer, with a header prepended. Now that qio_channel_websock_encode accepts a struct iovec, we can trivially remove this bounce buffering and write directly to encoutput. In doing so, we also now correctly validate the encoutput size against the QIO_CHANNEL_WEBSOCK_MAX_BUFFER limit. Reviewed-by: Eric Blake Signed-off-by: Daniel P. Berrange (cherry picked from commit 8dfd5f96515ca20c4eb109cb0ee28e2bb32fc505) NB, include of iov.h was pushed into previous patch to fix bisect buld. Signed-off-by: Miroslav Rezanina --- include/io/channel-websock.h | 1 - io/channel-websock.c | 63 +++++++++++++++++++------------------------- 2 files changed, 27 insertions(+), 37 deletions(-) diff --git a/include/io/channel-websock.h b/include/io/channel-websock.h index 3762707..a7e5e92 100644 --- a/include/io/channel-websock.h +++ b/include/io/channel-websock.h @@ -59,7 +59,6 @@ struct QIOChannelWebsock { Buffer encinput; Buffer encoutput; Buffer rawinput; - Buffer rawoutput; size_t payload_remain; size_t pong_remain; QIOChannelWebsockMask mask; diff --git a/io/channel-websock.c b/io/channel-websock.c index 11b6039..e82b1be 100644 --- a/io/channel-websock.c +++ b/io/channel-websock.c @@ -634,19 +634,22 @@ static ssize_t qio_channel_websock_write_wire(QIOChannelWebsock *, Error **); static void qio_channel_websock_write_close(QIOChannelWebsock *ioc, uint16_t code, const char *reason) { - struct iovec iov; - buffer_reserve(&ioc->rawoutput, 2 + (reason ? strlen(reason) : 0)); - *(uint16_t *)(ioc->rawoutput.buffer + ioc->rawoutput.offset) = - cpu_to_be16(code); - ioc->rawoutput.offset += 2; + struct iovec iov[2] = { + { .iov_base = &code, .iov_len = sizeof(code) }, + }; + size_t niov = 1; + size_t size = iov[0].iov_len; + + cpu_to_be16s(&code); + if (reason) { - buffer_append(&ioc->rawoutput, reason, strlen(reason)); + iov[1].iov_base = (void *)reason; + iov[1].iov_len = strlen(reason); + size += iov[1].iov_len; + niov++; } - iov.iov_base = ioc->rawoutput.buffer; - iov.iov_len = ioc->rawoutput.offset; qio_channel_websock_encode(ioc, QIO_CHANNEL_WEBSOCK_OPCODE_CLOSE, - &iov, 1, iov.iov_len); - buffer_reset(&ioc->rawoutput); + iov, niov, size); qio_channel_websock_write_wire(ioc, NULL); qio_channel_shutdown(ioc->master, QIO_CHANNEL_SHUTDOWN_BOTH, NULL); } @@ -894,7 +897,6 @@ static void qio_channel_websock_finalize(Object *obj) buffer_free(&ioc->encinput); buffer_free(&ioc->encoutput); buffer_free(&ioc->rawinput); - buffer_free(&ioc->rawoutput); object_unref(OBJECT(ioc->master)); if (ioc->io_tag) { g_source_remove(ioc->io_tag); @@ -1104,8 +1106,8 @@ static ssize_t qio_channel_websock_writev(QIOChannel *ioc, Error **errp) { QIOChannelWebsock *wioc = QIO_CHANNEL_WEBSOCK(ioc); - size_t i; - ssize_t done = 0; + ssize_t want = iov_size(iov, niov); + ssize_t avail; ssize_t ret; if (wioc->io_err) { @@ -1118,32 +1120,21 @@ static ssize_t qio_channel_websock_writev(QIOChannel *ioc, return -1; } - for (i = 0; i < niov; i++) { - size_t want = iov[i].iov_len; - if ((want + wioc->rawoutput.offset) > QIO_CHANNEL_WEBSOCK_MAX_BUFFER) { - want = (QIO_CHANNEL_WEBSOCK_MAX_BUFFER - wioc->rawoutput.offset); - } - if (want == 0) { - goto done; - } - - buffer_reserve(&wioc->rawoutput, want); - buffer_append(&wioc->rawoutput, iov[i].iov_base, want); - done += want; - if (want < iov[i].iov_len) { - break; - } + avail = wioc->encoutput.offset >= QIO_CHANNEL_WEBSOCK_MAX_BUFFER ? + 0 : (QIO_CHANNEL_WEBSOCK_MAX_BUFFER - wioc->encoutput.offset); + if (want > avail) { + want = avail; } - done: - if (wioc->rawoutput.offset) { - struct iovec iov = { .iov_base = wioc->rawoutput.buffer, - .iov_len = wioc->rawoutput.offset }; + if (want) { qio_channel_websock_encode(wioc, QIO_CHANNEL_WEBSOCK_OPCODE_BINARY_FRAME, - &iov, 1, iov.iov_len); - buffer_reset(&wioc->rawoutput); + iov, niov, want); } + + /* Even if want == 0, we'll try write_wire in case there's + * pending data we could usefully flush out + */ ret = qio_channel_websock_write_wire(wioc, errp); if (ret < 0 && ret != QIO_CHANNEL_ERR_BLOCK) { @@ -1153,11 +1144,11 @@ static ssize_t qio_channel_websock_writev(QIOChannel *ioc, qio_channel_websock_set_watch(wioc); - if (done == 0) { + if (want == 0) { return QIO_CHANNEL_ERR_BLOCK; } - return done; + return want; } static int qio_channel_websock_set_blocking(QIOChannel *ioc, -- 1.8.3.1