[#4131] ppp hangs at ioctl(TIOCSETD)

Submitted By: Yi Li

Open Date

2008-05-28 05:56:52 Close Date

2008-06-27 05:19:15

Priority:

Medium Assignee:

Yi Li

Status:

Closed Fixed In Release:

N/A

Found In Release:

N/A Release:

trunk,2008r1

Category:

N/A Board:

EZKIT Lite

Processor:

BF548 Silicon Revision:

Is this bug repeatable?:

Yes Resolution:

Fixed

Uboot version or rev.:

Toolchain version or rev.:

08r1-8

App binary format:

N/A

Summary: ppp hangs at ioctl(TIOCSETD)

Details:

I tried to start ppp link over serial port, according to:

docs.blackfin.uclinux.org/doku.php?id=uclinux-dist:ppp.

Kernel configure, pppd configure are the same as the document.

When starting pppd (using telnet, the serial terminal emulator is closed), it hangs. strace shows:

root:/> strace pppd

[snip]

open("/dev/ttyBF0", O_RDWR|O_NONBLOCK) = 7

fcntl(7, F_GETFL) = 0x802 (flags O_RDWR|O_NONBLOCK)

fcntl(7, F_SETFL, O_RDWR) = 0

ioctl(7, TIOCMBIS, [TIOCM_DTR]) = 0

ioctl(7, SNDCTL_TMR_TIMEBASE or TCGETS, {B57600 opost -isig -icanon -echo ...}) = 0

ioctl(7, SNDCTL_TMR_CONTINUE or TCSETSF, {B115200 -opost -isig -icanon -echo ...}) = 0

fcntl(6, F_SETLKW, {type=F_WRLCK, whence=SEEK_SET, start=544, len=1}) = 0

fcntl(6, F_SETLK, {type=F_WRLCK, whence=SEEK_SET, start=1092, len=1}) = 0

fcntl(6, F_SETLK, {type=F_UNLCK, whence=SEEK_SET, start=1092, len=1}) = 0

fcntl(6, F_SETLKW, {type=F_WRLCK, whence=SEEK_SET, start=164, len=1}) = 0

fcntl(6, F_SETLKW, {type=F_UNLCK, whence=SEEK_SET, start=164, len=1}) = 0

fcntl(6, F_SETLKW, {type=F_WRLCK, whence=SEEK_SET, start=164, len=1}) = 0

fcntl(6, F_SETLKW, {type=F_UNLCK, whence=SEEK_SET, start=164, len=1}) = 0

fcntl(6, F_SETLKW, {type=F_UNLCK, whence=SEEK_SET, start=544, len=1}) = 0

ioctl(7, TIOCEXCL, 0) = 0

ioctl(7, TIOCSETD

[hangs here]

I am not sure this is configuration issue or ppp problem.

Follow-ups

--- Yi Li 2008-06-27 06:19:18

This is not a bug.

We need to disable blackfin serial console when using PPP on serial line,

otherwise, pppd will hangs at:

ioctl(TIOCSETD) --> tty_set_ldisc()

--->

if (wait_event_interruptible(tty_ldisc_wait, tty->ldisc.refcount == 0) <

return -ERESTARTSYS;

the serial console uses the line discipline. Simply close the console will not

release the line discipline (a bug?).

If enabled the serial console, I boot uboot with the option:

Kernel command line:

ip=10.99.23.104:10.99.23.118:10.99.23.1:255.255.255.0:BF537:eth0:off

Then telnet to the board when kernel booted (did not open serial console at

all), pppd still hangs.

--- Mike Frysinger 2008-06-28 10:31:06

if you enable the serial console, you need to run pppd in the serial console,

you cant run it from the telnet session

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[#4131] ppp hangs at ioctl(TIOCSETD)