The patch titled
Serial-Core: adds atomic context debug code.
has been added to the -mm tree. Its filename is
serial-core-adds-atomic-context-debug-code.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Serial-Core: adds atomic context debug code.
From: "Luiz Fernando N. Capitulino" <lcapitulino@xxxxxxxxxxxxxxx>
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.
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@xxxxxxxxxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
drivers/serial/serial_core.c | 6 ++++++
1 file changed, 6 insertions(+)
diff -puN drivers/serial/serial_core.c~serial-core-adds-atomic-context-debug-code drivers/serial/serial_core.c
--- a/drivers/serial/serial_core.c~serial-core-adds-atomic-context-debug-code
+++ a/drivers/serial/serial_core.c
@@ -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;
@@ -2056,6 +2060,8 @@ uart_configure_port(struct uart_driver *
{
unsigned int flags;
+ might_sleep();
+
/*
* If there isn't a port here, don't do anything further.
*/
_
Patches currently in -mm which might be from lcapitulino@xxxxxxxxxxxxxxx are
origin.patch
serial-core-adds-atomic-context-debug-code.patch
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