The lock usage was described with its introduction in commit9005b2a758
. It was necessary because PTY write() shares more state than GIOChannel with other operations. This made char-pty a bit different from other chardev, that only lock around the write operation. This was apparent in commit7b3621f47a
, which introduced an idle source to avoid the lock. By removing the PTY chardev state sharing on write() with previous patch, we can remove the lock and the idle source. Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Message-Id: <20190206174328.9736-7-marcandre.lureau@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
250 lines
6.7 KiB
C
250 lines
6.7 KiB
C
/*
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* QEMU System Emulator
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*
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* Copyright (c) 2003-2008 Fabrice Bellard
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "qemu/osdep.h"
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#include "qapi/error.h"
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#include "qemu-common.h"
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#include "chardev/char.h"
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#include "io/channel-file.h"
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#include "qemu/sockets.h"
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#include "qemu/error-report.h"
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#include "chardev/char-io.h"
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typedef struct {
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Chardev parent;
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QIOChannel *ioc;
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int read_bytes;
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int connected;
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GSource *timer_src;
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} PtyChardev;
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#define PTY_CHARDEV(obj) OBJECT_CHECK(PtyChardev, (obj), TYPE_CHARDEV_PTY)
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static void pty_chr_state(Chardev *chr, int connected);
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static void pty_chr_timer_cancel(PtyChardev *s)
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{
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if (s->timer_src) {
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g_source_destroy(s->timer_src);
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g_source_unref(s->timer_src);
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s->timer_src = NULL;
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}
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}
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static gboolean pty_chr_timer(gpointer opaque)
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{
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struct Chardev *chr = CHARDEV(opaque);
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PtyChardev *s = PTY_CHARDEV(opaque);
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pty_chr_timer_cancel(s);
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if (!s->connected) {
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/* Next poll ... */
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qemu_chr_be_update_read_handlers(chr, chr->gcontext);
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}
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return FALSE;
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}
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static void pty_chr_rearm_timer(Chardev *chr, int ms)
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{
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PtyChardev *s = PTY_CHARDEV(chr);
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char *name;
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pty_chr_timer_cancel(s);
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name = g_strdup_printf("pty-timer-%s", chr->label);
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s->timer_src = qemu_chr_timeout_add_ms(chr, ms, pty_chr_timer, chr);
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g_source_set_name(s->timer_src, name);
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g_free(name);
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}
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static void pty_chr_update_read_handler(Chardev *chr)
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{
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PtyChardev *s = PTY_CHARDEV(chr);
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GPollFD pfd;
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int rc;
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QIOChannelFile *fioc = QIO_CHANNEL_FILE(s->ioc);
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pfd.fd = fioc->fd;
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pfd.events = G_IO_OUT;
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pfd.revents = 0;
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do {
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rc = g_poll(&pfd, 1, 0);
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} while (rc == -1 && errno == EINTR);
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assert(rc >= 0);
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if (pfd.revents & G_IO_HUP) {
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pty_chr_state(chr, 0);
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} else {
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pty_chr_state(chr, 1);
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}
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}
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static int char_pty_chr_write(Chardev *chr, const uint8_t *buf, int len)
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{
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PtyChardev *s = PTY_CHARDEV(chr);
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if (!s->connected) {
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return len;
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}
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return io_channel_send(s->ioc, buf, len);
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}
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static GSource *pty_chr_add_watch(Chardev *chr, GIOCondition cond)
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{
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PtyChardev *s = PTY_CHARDEV(chr);
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if (!s->connected) {
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return NULL;
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}
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return qio_channel_create_watch(s->ioc, cond);
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}
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static int pty_chr_read_poll(void *opaque)
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{
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Chardev *chr = CHARDEV(opaque);
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PtyChardev *s = PTY_CHARDEV(opaque);
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s->read_bytes = qemu_chr_be_can_write(chr);
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return s->read_bytes;
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}
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static gboolean pty_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque)
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{
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Chardev *chr = CHARDEV(opaque);
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PtyChardev *s = PTY_CHARDEV(opaque);
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gsize len;
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uint8_t buf[CHR_READ_BUF_LEN];
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ssize_t ret;
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len = sizeof(buf);
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if (len > s->read_bytes) {
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len = s->read_bytes;
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}
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if (len == 0) {
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return TRUE;
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}
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ret = qio_channel_read(s->ioc, (char *)buf, len, NULL);
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if (ret <= 0) {
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pty_chr_state(chr, 0);
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return FALSE;
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} else {
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pty_chr_state(chr, 1);
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qemu_chr_be_write(chr, buf, ret);
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}
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return TRUE;
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}
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static void pty_chr_state(Chardev *chr, int connected)
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{
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PtyChardev *s = PTY_CHARDEV(chr);
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if (!connected) {
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remove_fd_in_watch(chr);
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s->connected = 0;
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/* (re-)connect poll interval for idle guests: once per second.
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* We check more frequently in case the guests sends data to
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* the virtual device linked to our pty. */
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pty_chr_rearm_timer(chr, 1000);
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} else {
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pty_chr_timer_cancel(s);
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if (!s->connected) {
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s->connected = 1;
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qemu_chr_be_event(chr, CHR_EVENT_OPENED);
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}
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if (!chr->gsource) {
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chr->gsource = io_add_watch_poll(chr, s->ioc,
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pty_chr_read_poll,
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pty_chr_read,
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chr, chr->gcontext);
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}
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}
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}
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static void char_pty_finalize(Object *obj)
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{
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Chardev *chr = CHARDEV(obj);
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PtyChardev *s = PTY_CHARDEV(obj);
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pty_chr_state(chr, 0);
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object_unref(OBJECT(s->ioc));
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pty_chr_timer_cancel(s);
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qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
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}
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static void char_pty_open(Chardev *chr,
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ChardevBackend *backend,
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bool *be_opened,
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Error **errp)
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{
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PtyChardev *s;
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int master_fd, slave_fd;
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char pty_name[PATH_MAX];
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char *name;
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master_fd = qemu_openpty_raw(&slave_fd, pty_name);
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if (master_fd < 0) {
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error_setg_errno(errp, errno, "Failed to create PTY");
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return;
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}
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close(slave_fd);
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qemu_set_nonblock(master_fd);
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chr->filename = g_strdup_printf("pty:%s", pty_name);
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error_printf("char device redirected to %s (label %s)\n",
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pty_name, chr->label);
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s = PTY_CHARDEV(chr);
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s->ioc = QIO_CHANNEL(qio_channel_file_new_fd(master_fd));
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name = g_strdup_printf("chardev-pty-%s", chr->label);
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qio_channel_set_name(QIO_CHANNEL(s->ioc), name);
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g_free(name);
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s->timer_src = NULL;
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*be_opened = false;
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}
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static void char_pty_class_init(ObjectClass *oc, void *data)
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{
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ChardevClass *cc = CHARDEV_CLASS(oc);
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cc->open = char_pty_open;
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cc->chr_write = char_pty_chr_write;
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cc->chr_update_read_handler = pty_chr_update_read_handler;
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cc->chr_add_watch = pty_chr_add_watch;
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}
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static const TypeInfo char_pty_type_info = {
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.name = TYPE_CHARDEV_PTY,
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.parent = TYPE_CHARDEV,
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.instance_size = sizeof(PtyChardev),
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.instance_finalize = char_pty_finalize,
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.class_init = char_pty_class_init,
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};
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static void register_types(void)
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{
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type_register_static(&char_pty_type_info);
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}
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type_init(register_types);
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