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 <[EMAIL PROTECTED]>
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
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
_______________________________________________
linux-usb-devel@lists.sourceforge.net
To unsubscribe, use the last form field at:
https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
