lkml.org 
[lkml]   [2006]   [Jul]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] Serial-Core: adds atomic context debug code.
 Andrew,

While porting the USB-Serial layer to the Serial Core API [1], we found that
usb-serial devices must be able to sleep in the get_mctrl() and set_mctrl()
callbacks [2]. But, unfortunately, those callbacks are called with a spinlock
held.

The solution is to switch from the spinlock to a mutex.

But turns out that we have no sure whether uart_update_mctrl(),
uart_startup() and uart_configure_port() (which calls {get,set}_mctrl()) are
called from atomic context or not.

This patch adds might_sleep() calls to them in order to help us to find the
answer.

Please, note that this is just a debug patch to stay in -mm for a while,
ie, it's not a submission for mainline kernel.

[1] http://marc.theaimsgroup.com/?l=linux-usb-devel&m=114921742628790&w=2
[2] http://lkml.org/lkml/2006/6/13/242

Signed-off-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>

diff -purN linux-2.6.17.orig/drivers/serial/serial_core.c linux-2.6.17/drivers/serial/serial_core.c
--- linux-2.6.17.orig/drivers/serial/serial_core.c 2006-07-04 16:35:47.796329000 -0300
+++ linux-2.6.17/drivers/serial/serial_core.c 2006-07-04 16:35:47.820333205 -0300
@@ -128,6 +128,8 @@ uart_update_mctrl(struct uart_port *port
unsigned long flags;
unsigned int old;

+ might_sleep();
+
spin_lock_irqsave(&port->lock, flags);
old = port->mctrl;
port->mctrl = (old & ~clear) | set;
@@ -150,6 +152,8 @@ static int uart_startup(struct uart_stat
unsigned long page;
int retval = 0;

+ might_sleep();
+
if (info->flags & UIF_INITIALIZED)
return 0;

@@ -2055,6 +2059,8 @@ uart_configure_port(struct uart_driver *
{
unsigned int flags;

+ might_sleep();
+
/*
* If there isn't a port here, don't do anything further.
*/

--
Luiz Fernando N. Capitulino
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-07-04 21:44    [W:0.025 / U:0.148 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site