Messages in this thread | | | Date | Fri, 15 Jul 2005 08:28:59 +0100 | From | Russell King <> | Subject | Re: 2.6.9: serial_core: uart_open |
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On Thu, Jul 14, 2005 at 03:35:07PM -0700, karl malbrain wrote: > AT LAST I HAVE SOME DATA!!! > > The problem is that ALL SYSTEM CALLS to open "/dev/tty" are blocking!! even > with O_NDELAY set and even from completely disjoint sessions. I discovered > this via issuing "strace sh". That's why the new xterm windows froze. > > The original process doing the open("/dev/ttyS1", O_RDWR) is listed in the > ps aux listing as status S+.
Ok, 'S' means it's sleeping.
Can you enable Magic SYSRQ, and ensure that you have a large kernel log buffer (the LOG_BUF_SHIFT configuration symbol). Ensure that /proc/sys/kernel/sysrq is 1, and re-run your test such that you have something else waiting (eg, the strace sh). Then hit Alt-SysRQ-T.
You can then read the kernel messages with dmesg - you may need the -s argument to capture the entire kernel buffer.
This will tell us where all processes are sleeping.
-- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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