From mboxrd@z Thu Jan 1 00:00:00 1970 From: VomLehn Subject: [PATCH] Wait for console to become available Date: Tue, 14 Apr 2009 16:28:36 -0700 Message-ID: <20090414232835.GA20307@cuplxvomd02.corp.sa.net> Mime-Version: 1.0 Return-path: Content-Disposition: inline DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; l=1926; t=1239751716; x=1240615716; c=relaxed/simple; s=sjdkim2002; h=Content-Type:From:Subject:Content-Transfer-Encoding:MIME-Version; d=cisco.com; i=dvomlehn@cisco.com; z=From:=20VomLehn=20 |Subject:=20[PATCH]=20Wait=20for=20console=20to=20become=20 available |Sender:=20; bh=E82uSc4OrgdHJuRZA//A6kk0iH+a8AxsCO6Wn6QKy9A=; b=VlglKsgXN9ZwtBVnTWyTRb1VZq/yu2GILwQpNP1zq3lp9LJ+gBpFTwqTBL 77zXsCa40xR7Den6mhTK3DDuZhMqUaxSO8MfP/zjQNptUKfJutM5fmLhF5fv x5G5xVAOyh; Sender: linux-embedded-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Linux Kernel Mailing List Cc: Linux Embedded Mailing List Work to improve boot times appears to be successful enough that a race condition has been created between the open of /dev/console in init_post and USB serial device initialization. Embedded systems are probably the primary users of USB serial devices, though I can certainly image blade servers using them, as well. This patch works for me and, though it's possible this is all that needs to be done, I think it's likely there are some other changes required, as well. Signed-off-by: David VomLehn --- kernel/printk.c | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-) diff --git a/kernel/printk.c b/kernel/printk.c index e3602d0..39f554a 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -104,6 +104,10 @@ static unsigned log_start; /* Index into log_buf: next char to be read by syslog static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ +/* Definitions for waiting until a console is registered */ +#define MAX_CONSOLE_WAIT msecs_to_jiffies(2000) +static DECLARE_WAIT_QUEUE_HEAD(console_wait); + /* * Array of consoles built from command line options (console=) */ @@ -1062,6 +1066,10 @@ struct tty_driver *console_device(int *index) struct console *c; struct tty_driver *driver = NULL; + /* Wait a while for a console to show up. If one doesn't show up + * for too long, we'll just continue without a console. */ + wait_event_timeout(console_wait, console_drivers, MAX_CONSOLE_WAIT); + acquire_console_sem(); for (c = console_drivers; c != NULL; c = c->next) { if (!c->device) @@ -1211,6 +1219,7 @@ void register_console(struct console *console) spin_unlock_irqrestore(&logbuf_lock, flags); } release_console_sem(); + wake_up_all(&console_wait); } EXPORT_SYMBOL(register_console);