Re: ldisc problems with 2.6.32-2.6.37-rc2 (at least)

[Sergey Lapin <slapin@ossfans.org>]

On Wed, Nov 24, 2010 at 08:45:23PM +0100, Jiri Slaby wrote:
> On 11/24/2010 08:43 PM, Jiri Slaby wrote:
> > Could you provide disassembly of tty_set_ldisc? E.g. by extracting it from:
> > objdump -d drivers/tty/tty_ldisc.o
> 
> Or maybe better after linking:
> objdump -d vmlinux
> 
> thanks,
> -- 
> js
> suse labs

This is reproduced on second run of application I submitted on my previous mail:

WARNING: at drivers/tty/tty_ldisc.c:451 tty_ldisc_open+0x3c/0x9c()
Modules linked in:
[<c002c694>] (unwind_backtrace+0x0/0xe4) from [<c0037ad4>] (warn_slowpath_common+0x4c/0x64)
[<c0037ad4>] (warn_slowpath_common+0x4c/0x64) from [<c0037b04>] (warn_slowpath_null+0x18/0x1c)
[<c0037b04>] (warn_slowpath_null+0x18/0x1c) from [<c01bb88c>] (tty_ldisc_open+0x3c/0x9c)
[<c01bb88c>] (tty_ldisc_open+0x3c/0x9c) from [<c01bc110>] (tty_set_ldisc+0x328/0x454)
[<c01bc110>] (tty_set_ldisc+0x328/0x454) from [<c01b6624>] (tty_ioctl+0x83c/0xac4)
[<c01b6624>] (tty_ioctl+0x83c/0xac4) from [<c00b383c>] (vfs_ioctl+0x20/0x3c)
[<c00b383c>] (vfs_ioctl+0x20/0x3c) from [<c00b3f9c>] (do_vfs_ioctl+0x540/0x598)
[<c00b3f9c>] (do_vfs_ioctl+0x540/0x598) from [<c00b4028>] (sys_ioctl+0x34/0x54)
[<c00b4028>] (sys_ioctl+0x34/0x54) from [<c0027a80>] (ret_fast_syscall+0x0/0x2c)
---[ end trace 478cfbb6d09c3354 ]---
can't set ldisc: Cannot allocate memory
root@sheevaplug:~# ./a.out /dev/ttyS1 
.
^C
root@sheevaplug:~# ./a.out /dev/ttyS1 
------------[ cut here ]------------
WARNING: at drivers/tty/tty_ldisc.c:451 tty_ldisc_open+0x3c/0x9c()
Modules linked in:
[<c002c694>] (unwind_backtrace+0x0/0xe4) from [<c0037ad4>] (warn_slowpath_common+0x4c/0x64)
[<c0037ad4>] (warn_slowpath_common+0x4c/0x64) from [<c0037b04>] (warn_slowpath_null+0x18/0x1c)
[<c0037b04>] (warn_slowpath_null+0x18/0x1c) from [<c01bb88c>] (tty_ldisc_open+0x3c/0x9c)
[<c01bb88c>] (tty_ldisc_open+0x3c/0x9c) from [<c01bc110>] (tty_set_ldisc+0x328/0x454)
[<c01bc110>] (tty_set_ldisc+0x328/0x454) from [<c01b6624>] (tty_ioctl+0x83c/0xac4)
[<c01b6624>] (tty_ioctl+0x83c/0xac4) from [<c00b383c>] (vfs_ioctl+0x20/0x3c)
[<c00b383c>] (vfs_ioctl+0x20/0x3c) from [<c00b3f9c>] (do_vfs_ioctl+0x540/0x598)
[<c00b3f9c>] (do_vfs_ioctl+0x540/0x598) from [<c00b4028>] (sys_ioctl+0x34/0x54)
[<c00b4028>] (sys_ioctl+0x34/0x54) from [<c0027a80>] (ret_fast_syscall+0x0/0x2c)
---[ end trace 478cfbb6d09c3355 ]---
can't set ldisc: Cannot allocate memory

Initially I run it, everything is ok.
Then I run it and get error and backtrace.
And if I run it again, everything is ok again, repeatedly. Probably some resources are properly
set up in error condition, and not in normal condition.

I use ARM machine for testing and x86, bug is architecture-independent.

addr2lines:
c01bb88c drivers/tty/tty_ldisc.c:452
c01bc110 drivers/tty/tty_ldisc.c:499
c01b6624 drivers/tty/tty_io.c:2402
c00b383c fs/ioctl.c:44
c00b3f9c fs/ioctl.c:596
c00b4028 include/linux/file.h:26