On Friday 18 February 2005 16:33, Anton Altaparmakov wrote: > On Wed, 2005-02-16 at 19:35 +0100, Blaisorblade wrote: > > On Monday 14 February 2005 12:48, Anton Altaparmakov wrote: > > > Hi, > > > > > > I get a few Debug messages of the form from UML: > > > > > > Debug: sleeping function called from invalid context at > > > include/asm/arch/semaphore.h:107 > > > in_atomic():0, irqs_disabled():1 > > > Call Trace: > > > 087d77b0: [<0809aaa5>] __might_sleep+0x135/0x180 > > > 087d77d8: [<084d377f>] mcount+0xf/0x20 > > > 087d77e0: [<0807cc13>] uml_console_write+0x33/0x80 > > > > > > Most are coming via uml_console_write. > > > > The problem is that the UML tty drivers use a semaphore instead of a > > spinlock for the locking, which also causes some other problems. > > > > The attached patch should fix this, but I've not yet made sure it is not > > deadlock-prone (I didn't hit any during some very limited testing). > > > > So it's not yet ready for 2.6.11. > > Trying with the above patch in now only get two "sleeping function > called from invalid context" warnings during boot and none during > running. I'll look at whether I can produce them... if it's no problem, post their traces anyway, please. > However I get a lot of those errors: > > arch/um/drivers/line.c:262: spin_lock(arch/um/drivers/line.c:085b5900) > already locked by arch/um/drivers/line.c/262 Ok, I'll be looking into them ASAP (which infortunately means not very soon, sorry).
At a quick look, I see that line 262 is a "spin_lock" called by line_write_interrupt. I used spin_lock_irqsave everywhere else... but actually the interrupt must explicitly disable interrupts (I forgot) so, the simple answer seems to be using spin_lock_irqsave() would fix it. I cannot make a patch now. > Also both before and after the patch I see a lot of messages like: > > kernel: line_write_room: tty2: no room left in buffer I've never seen them... which is your test case? Anyway, I'm not sure this is a needed warning: in include/linux/tty_driver.h, the .write_room member must tell the available space... it's reasonable that the TTY layer will call a flush_buffers function. However, looking at stdio_console, I'm seeing that, in fact, there is no flush_chars function(!!). I'll provide one ASAP. -- Paolo Giarrusso, aka Blaisorblade Linux registered user n. 292729 http://www.user-mode-linux.org/~blaisorblade - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
