Messages in this thread | | | Date | Wed, 19 Dec 2007 17:40:44 +0100 | From | "Remy Bohmer" <> | Subject | Re: [PATCH v2 0/6] atmel_serial: Cleanups, irq handler splitup & DMA |
| |
Hello Haavard,
> Could you try the patch below? It's a bit strange that you got an oops > though...
It is not really strange... spinlocks are mutexes on preempt-rt, and recursive mutex locking is not allowed, this is one differences with the mainline spinlock.
But... I tried that patch, and it works a lot better, no oopses anymore, but I noticed that I sometimes get an input overrun (ttyS0: 1 input overrun(s) ) during stress conditions. This is something I did not notice before, maybe it was already there, or has something changed in this area that it is now more sensitive for this?
Kind Regards,
Remy
2007/12/19, Haavard Skinnemoen <hskinnemoen@atmel.com>: > On Wed, 19 Dec 2007 16:57:04 +0100 > "Remy Bohmer" <linux@bohmer.net> wrote: > > > Hello Haavard, > > > > Sorry.. But I get an Oops on Preempt-RT with the latest set of > > patches. I did not see it earlier today with the other set of patches. > > Hmm...from the backtrace, it looks like lock recursion -- port->lock is > held for the whole duration of the tasklet, but we somehow end up in > uart_start(), which grabs the lock again. > > Could you try the patch below? It's a bit strange that you got an oops > though... > > Haavard > > diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c > index 7967054..948c643 100644 > --- a/drivers/serial/atmel_serial.c > +++ b/drivers/serial/atmel_serial.c > @@ -666,7 +666,13 @@ static void atmel_rx_from_ring(struct uart_port *port) > uart_insert_char(port, status, ATMEL_US_OVRE, c.ch, flg); > } > > + /* > + * Drop the lock here since it might end up calling > + * uart_start(), which takes the lock. > + */ > + spin_unlock(&port->lock); > tty_flip_buffer_push(port->info->tty); > + spin_lock(&port->lock); > } > > static void atmel_rx_from_dma(struct uart_port *port) >
| |