Messages in this thread Patch in this message | | | Date | Tue, 4 Jul 2006 16:41:38 -0300 | From | "Luiz Fernando N. Capitulino" <> | Subject | [PATCH] Serial-Core: adds atomic context debug code. |
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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. */
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