From fe8f6bd09c3f31978d41dfd03ea43b9874467fe7 Mon Sep 17 00:00:00 2001 From: Amit Shah Date: Mon, 21 Mar 2011 22:02:47 +0100 Subject: [PATCH] char: Equip the unix/tcp backend to handle nonblocking writes# Now that the infrastructure is in place to return -EAGAIN to callers, individual char drivers can set their update_fd_handlers() function to set or remove an fd's write handler. This handler checks if the driver became writable. A generic callback routine is used for unblocking writes and letting users of chardevs know that a driver became writable again. Signed-off-by: Amit Shah Signed-off-by: Cole Robinson --- qemu-char.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/qemu-char.c b/qemu-char.c index b46cc97..9f8608a 100644 --- a/qemu-char.c +++ b/qemu-char.c @@ -106,6 +106,19 @@ static QTAILQ_HEAD(CharDriverStateHead, CharDriverState) chardevs = QTAILQ_HEAD_INITIALIZER(chardevs); +/* + * Generic routine that gets called when chardev becomes writable. + * Lets chardev user know it's OK to send more data. + */ +static void char_write_unblocked(void *opaque) +{ + CharDriverState *chr = opaque; + + chr->write_blocked = false; + chr->chr_disable_write_fd_handler(chr); + chr->chr_write_unblocked(chr->handler_opaque); +} + void qemu_chr_be_event(CharDriverState *s, int event) { /* Keep track if the char device is open */ @@ -2503,6 +2516,25 @@ static void tcp_chr_close(CharDriverState *chr) qemu_chr_be_event(chr, CHR_EVENT_CLOSED); } +static void tcp_enable_write_fd_handler(CharDriverState *chr) +{ + TCPCharDriver *s = chr->opaque; + + /* + * This function is called only after tcp_chr_connect() is called + * (either in 'server' mode or client mode. So we're sure of + * s->fd being initialised. + */ + enable_write_fd_handler(s->fd, char_write_unblocked); +} + +static void tcp_disable_write_fd_handler(CharDriverState *chr) +{ + TCPCharDriver *s = chr->opaque; + + disable_write_fd_handler(s->fd); +} + static CharDriverState *qemu_chr_open_socket(QemuOpts *opts) { CharDriverState *chr = NULL; @@ -2557,6 +2589,8 @@ static CharDriverState *qemu_chr_open_socket(QemuOpts *opts) chr->chr_close = tcp_chr_close; chr->get_msgfd = tcp_get_msgfd; chr->chr_add_client = tcp_chr_add_client; + chr->chr_enable_write_fd_handler = tcp_enable_write_fd_handler; + chr->chr_disable_write_fd_handler = tcp_disable_write_fd_handler; if (is_listen) { s->listen_fd = fd;