mirror of
https://gitlab.com/qemu-project/qemu
synced 2024-09-06 18:05:37 +00:00
![Leonardo Bras](/assets/img/avatar_default.png)
Add flags to io_writev and introduce io_flush as optional callback to QIOChannelClass, allowing the implementation of zero copy writes by subclasses. How to use them: - Write data using qio_channel_writev*(...,QIO_CHANNEL_WRITE_FLAG_ZERO_COPY), - Wait write completion with qio_channel_flush(). Notes: As some zero copy write implementations work asynchronously, it's recommended to keep the write buffer untouched until the return of qio_channel_flush(), to avoid the risk of sending an updated buffer instead of the buffer state during write. As io_flush callback is optional, if a subclass does not implement it, then: - io_flush will return 0 without changing anything. Also, some functions like qio_channel_writev_full_all() were adapted to receive a flag parameter. That allows shared code between zero copy and non-zero copy writev, and also an easier implementation on new flags. Signed-off-by: Leonardo Bras <leobras@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Message-Id: <20220513062836.965425-3-leobras@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
148 lines
4.3 KiB
C
148 lines
4.3 KiB
C
/*
|
|
* QEMU System Emulator
|
|
*
|
|
* Copyright (c) 2003-2008 Fabrice Bellard
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
* of this software and associated documentation files (the "Software"), to deal
|
|
* in the Software without restriction, including without limitation the rights
|
|
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
|
* copies of the Software, and to permit persons to whom the Software is
|
|
* furnished to do so, subject to the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice shall be included in
|
|
* all copies or substantial portions of the Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
|
|
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
|
|
* THE SOFTWARE.
|
|
*/
|
|
#include "qemu/osdep.h"
|
|
#include "chardev/char-io.h"
|
|
|
|
typedef struct IOWatchPoll {
|
|
GSource parent;
|
|
|
|
QIOChannel *ioc;
|
|
GSource *src;
|
|
|
|
IOCanReadHandler *fd_can_read;
|
|
GSourceFunc fd_read;
|
|
void *opaque;
|
|
} IOWatchPoll;
|
|
|
|
static IOWatchPoll *io_watch_poll_from_source(GSource *source)
|
|
{
|
|
return container_of(source, IOWatchPoll, parent);
|
|
}
|
|
|
|
static gboolean io_watch_poll_prepare(GSource *source,
|
|
gint *timeout)
|
|
{
|
|
IOWatchPoll *iwp = io_watch_poll_from_source(source);
|
|
bool now_active = iwp->fd_can_read(iwp->opaque) > 0;
|
|
bool was_active = iwp->src != NULL;
|
|
if (was_active == now_active) {
|
|
return FALSE;
|
|
}
|
|
|
|
if (now_active) {
|
|
iwp->src = qio_channel_create_watch(
|
|
iwp->ioc, G_IO_IN | G_IO_ERR | G_IO_HUP | G_IO_NVAL);
|
|
g_source_set_callback(iwp->src, iwp->fd_read, iwp->opaque, NULL);
|
|
g_source_add_child_source(source, iwp->src);
|
|
g_source_unref(iwp->src);
|
|
} else {
|
|
g_source_remove_child_source(source, iwp->src);
|
|
iwp->src = NULL;
|
|
}
|
|
return FALSE;
|
|
}
|
|
|
|
static gboolean io_watch_poll_dispatch(GSource *source, GSourceFunc callback,
|
|
gpointer user_data)
|
|
{
|
|
return G_SOURCE_CONTINUE;
|
|
}
|
|
|
|
static GSourceFuncs io_watch_poll_funcs = {
|
|
.prepare = io_watch_poll_prepare,
|
|
.dispatch = io_watch_poll_dispatch,
|
|
};
|
|
|
|
GSource *io_add_watch_poll(Chardev *chr,
|
|
QIOChannel *ioc,
|
|
IOCanReadHandler *fd_can_read,
|
|
QIOChannelFunc fd_read,
|
|
gpointer user_data,
|
|
GMainContext *context)
|
|
{
|
|
IOWatchPoll *iwp;
|
|
char *name;
|
|
|
|
iwp = (IOWatchPoll *) g_source_new(&io_watch_poll_funcs,
|
|
sizeof(IOWatchPoll));
|
|
iwp->fd_can_read = fd_can_read;
|
|
iwp->opaque = user_data;
|
|
iwp->ioc = ioc;
|
|
iwp->fd_read = (GSourceFunc) fd_read;
|
|
iwp->src = NULL;
|
|
|
|
name = g_strdup_printf("chardev-iowatch-%s", chr->label);
|
|
g_source_set_name((GSource *)iwp, name);
|
|
g_free(name);
|
|
|
|
g_source_attach(&iwp->parent, context);
|
|
g_source_unref(&iwp->parent);
|
|
return (GSource *)iwp;
|
|
}
|
|
|
|
void remove_fd_in_watch(Chardev *chr)
|
|
{
|
|
if (chr->gsource) {
|
|
g_source_destroy(chr->gsource);
|
|
chr->gsource = NULL;
|
|
}
|
|
}
|
|
|
|
int io_channel_send_full(QIOChannel *ioc,
|
|
const void *buf, size_t len,
|
|
int *fds, size_t nfds)
|
|
{
|
|
size_t offset = 0;
|
|
|
|
while (offset < len) {
|
|
ssize_t ret = 0;
|
|
struct iovec iov = { .iov_base = (char *)buf + offset,
|
|
.iov_len = len - offset };
|
|
|
|
ret = qio_channel_writev_full(
|
|
ioc, &iov, 1,
|
|
fds, nfds, 0, NULL);
|
|
if (ret == QIO_CHANNEL_ERR_BLOCK) {
|
|
if (offset) {
|
|
return offset;
|
|
}
|
|
|
|
errno = EAGAIN;
|
|
return -1;
|
|
} else if (ret < 0) {
|
|
errno = EINVAL;
|
|
return -1;
|
|
}
|
|
|
|
offset += ret;
|
|
}
|
|
|
|
return offset;
|
|
}
|
|
|
|
int io_channel_send(QIOChannel *ioc, const void *buf, size_t len)
|
|
{
|
|
return io_channel_send_full(ioc, buf, len, NULL, 0);
|
|
}
|