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From e8a6c8da28eb73704099b4ae2172bca7fa4d0bd7 Mon Sep 17 00:00:00 2001
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From: Amit Shah <amit.shah@redhat.com>
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Date: Mon, 21 Mar 2011 22:02:47 +0100
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Subject: [PATCH] char: Equip the unix/tcp backend to handle nonblocking
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writes#
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Now that the infrastructure is in place to return -EAGAIN to callers,
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individual char drivers can set their update_fd_handlers() function to
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set or remove an fd's write handler. This handler checks if the driver
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became writable.
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A generic callback routine is used for unblocking writes and letting
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users of chardevs know that a driver became writable again.
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Signed-off-by: Amit Shah <amit.shah@redhat.com>
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Signed-off-by: Cole Robinson <crobinso@redhat.com>
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---
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qemu-char.c | 34 ++++++++++++++++++++++++++++++++++
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1 file changed, 34 insertions(+)
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diff --git a/qemu-char.c b/qemu-char.c
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index 53803a3..e7cd42a 100644
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--- a/qemu-char.c
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+++ b/qemu-char.c
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@@ -106,6 +106,19 @@
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static QTAILQ_HEAD(CharDriverStateHead, CharDriverState) chardevs =
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QTAILQ_HEAD_INITIALIZER(chardevs);
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+/*
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+ * Generic routine that gets called when chardev becomes writable.
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+ * Lets chardev user know it's OK to send more data.
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+ */
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+static void char_write_unblocked(void *opaque)
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+{
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+ CharDriverState *chr = opaque;
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+
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+ chr->write_blocked = false;
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+ chr->chr_disable_write_fd_handler(chr);
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+ chr->chr_write_unblocked(chr->handler_opaque);
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+}
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+
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void qemu_chr_be_event(CharDriverState *s, int event)
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{
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/* Keep track if the char device is open */
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@@ -2508,6 +2521,25 @@ static void tcp_chr_close(CharDriverState *chr)
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qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
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}
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+static void tcp_enable_write_fd_handler(CharDriverState *chr)
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+{
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+ TCPCharDriver *s = chr->opaque;
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+
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+ /*
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+ * This function is called only after tcp_chr_connect() is called
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+ * (either in 'server' mode or client mode. So we're sure of
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+ * s->fd being initialised.
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+ */
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+ enable_write_fd_handler(s->fd, char_write_unblocked);
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+}
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+
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+static void tcp_disable_write_fd_handler(CharDriverState *chr)
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+{
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+ TCPCharDriver *s = chr->opaque;
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+
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+ disable_write_fd_handler(s->fd);
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+}
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+
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static CharDriverState *qemu_chr_open_socket(QemuOpts *opts)
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{
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CharDriverState *chr = NULL;
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@@ -2563,6 +2595,8 @@ static CharDriverState *qemu_chr_open_socket(QemuOpts *opts)
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chr->chr_close = tcp_chr_close;
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chr->get_msgfd = tcp_get_msgfd;
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chr->chr_add_client = tcp_chr_add_client;
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+ chr->chr_enable_write_fd_handler = tcp_enable_write_fd_handler;
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+ chr->chr_disable_write_fd_handler = tcp_disable_write_fd_handler;
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if (is_listen) {
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s->listen_fd = fd;
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--
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1.8.1
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