From d79a580936396bbcd2f4fae2c6215f9cf81e3c0d Mon Sep 17 00:00:00 2001 From: Jeff Dike Date: Sat, 10 Feb 2007 01:43:52 -0800 Subject: [PATCH] uml: console locking fixes Clean up the console driver locking. There are various problems here, including sleeping under a spinlock and spinlock recursion, some of which are fixed here. This patch deals with the locking involved with opens and closes. The problem is that an mconsole request to change a console's configuration can race with an open. Changing a configuration should only be done when a console isn't opened. Also, an open must be looking at a stable configuration. In addition, a get configuration request must observe the same locking since it must also see a stable configuration. With the old locking, it was possible for this to hang indefinitely in some cases because open would block for a long time waiting for a connection from the host while holding the lock needed by the mconsole request. As explained in the long comment, this is fixed by adding a spinlock for the use count and configuration and a mutex for the actual open and close. Signed-off-by: Jeff Dike Cc: Paolo 'Blaisorblade' Giarrusso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/drivers/stdio_console.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'arch/um/drivers/stdio_console.c') diff --git a/arch/um/drivers/stdio_console.c b/arch/um/drivers/stdio_console.c index 7a4897e27f42..9b2dd0b8a43b 100644 --- a/arch/um/drivers/stdio_console.c +++ b/arch/um/drivers/stdio_console.c @@ -83,9 +83,9 @@ static struct lines console_lines = LINES_INIT(MAX_TTYS); /* The array is initialized by line_init, which is an initcall. The * individual elements are protected by individual semaphores. */ -struct line vts[MAX_TTYS] = { LINE_INIT(CONFIG_CON_ZERO_CHAN, &driver), - [ 1 ... MAX_TTYS - 1 ] = - LINE_INIT(CONFIG_CON_CHAN, &driver) }; +static struct line vts[MAX_TTYS] = { LINE_INIT(CONFIG_CON_ZERO_CHAN, &driver), + [ 1 ... MAX_TTYS - 1 ] = + LINE_INIT(CONFIG_CON_CHAN, &driver) }; static int con_config(char *str) { -- cgit v1.2.2