hi,
Prevousely i was working on an sms related program using a ftdichip modem in
2.6.30-gentoor8 linux with ftdi_sio driver v1.4.3.
But i was running into a weird situation:
when OS starts up, my program will try to open /dev/ttyUSB0 infinitely
without sleep until it succeeds(due to be not considered properly when
coding), and then i plugin my USB serial modem, a bug message will
show up immediately with dmesg, and if i unplug modem, the system will
have no response. Then my program may be killed or be in state D.
the BUG message copied from dmesg:
[ 43.769794] BUG: unable to handle kernel NULL pointer dereference
at 00000074
[ 43.775687] IP: [<405829ba>] _spin_lock_irqsave+0x8/0x1a
[ 43.775687] *pdpt = 000000009ad51001 <6>usb 2-2: Detected FT232BM
[ 43.785760] usb 2-2: FTDI USB Serial Device converter now attached
to ttyUSB0
[ 43.785840] drivers/usb/core/inode.c: creating file '002'
[ 43.785686] *pde = 0000000000000000
[ 43.785686] Oops: 0002 [#1] SMP
[ 43.785686] last sysfs file:
[ 43.785686] Modules linked in: ixgbe igb dca e1000e e1000
[ 43.785686]
[ 43.785686] Pid: 1059, comm: smssp.orig Not tainted (2.6.30-gentoo-
r8 #24) AM5400B
[ 43.785686] EIP: 0060:[<405829ba>] EFLAGS: 00010046 CPU: 1
[ 43.785686] EIP is at _spin_lock_irqsave+0x8/0x1a
[ 43.785686] EAX: 00000074 EBX: 00000074 ECX: 00000246 EDX: 00000100
[ 43.785686] ESI: dade8400 EDI: 00000000 EBP: d903ba00 ESP: da43be28
[ 43.785686] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
[ 43.785686] Process smssp.orig (pid: 1059, ti=da43a000
task=dad6f710 task.ti=da43a000)
[ 43.785686] Stack:
[ 43.785686] 4047d5c8 da5f3000 4045bbb5 4073d460 d903ba00 d9001340
dade8400 404799fd
[ 43.785686] d88bfb40 d9001378 d903bad0 d903ba58 d903ba04 da652300
dade8400 d88bfb40
[ 43.785686] dade8400 4035d144 da8e48a8 00000000 00000902 00000100
0bc00000 00000000
[ 43.785686] Call Trace:
[ 43.785686] [<4047d5c8>] ? ftdi_open+0x42/0x1a1
[ 43.785686] [<4045bbb5>] ? usb_autopm_do_interface+0x9a/0xa1
[ 43.785686] [<404799fd>] ? serial_open+0x112/0x189
[ 43.785686] [<4035d144>] ? tty_open+0x27b/0x3a9
[ 43.785686] [<40293524>] ? chrdev_open+0x128/0x152
[ 43.785686] [<402a198c>] ? mntput_no_expire+0x12/0xe0
[ 43.785686] [<402933fc>] ? chrdev_open+0x0/0x152
[ 43.785686] [<4028f5dd>] ? __dentry_open+0x113/0x1e9
[ 43.785686] [<40290413>] ? nameidata_to_filp+0x29/0x3c
[ 43.785686] [<40299ac4>] ? do_filp_open+0x3ab/0x689
[ 43.785686] [<4025d5bb>] ? __rcu_process_callbacks+0x57/0x159
[ 43.785686] [<40236d6a>] ? autoremove_wake_function+0x0/0x2d
[ 43.785686] [<402a05ff>] ? alloc_fd+0x5e/0xd0
[ 43.785686] [<4028f3ea>] ? do_sys_open+0x44/0xb4
[ 43.785686] [<4028f49e>] ? sys_open+0x1e/0x23
[ 43.785686] [<40202964>] ? sysenter_do_call+0x12/0x22
[ 43.785686] Code: 74 05 e8 3e fe ff ff c3 fa f0 83 28 01 79 05 e8
4d fe ff ff c3 f0 81 00 00 00 00 01 fb c3 f0 ff 00 fb c3 9c 59 fa ba
00 01 00 00 <f0> 66 0f c1 10 38 f2 74 06 f3 90 8a 10 eb f6 89 c8 c3 9c
5a fa
[ 43.785686] EIP: [<405829ba>] _spin_lock_irqsave+0x8/0x1a SS:ESP
0068:da43be28
[ 43.785686] CR2: 0000000000000074
[ 43.785686] ---[ end trace b68e6189f2a3d267 ]---
[ 45.882827] hub 1-0:1.0: hub_suspend
[ 45.886552] usb usb1: bus auto-suspend
[ 45.890434] ehci_hcd 0000:00:1d.7: suspend root hub
here is my equivalent toy test program to reproduce this issue:
/*
*
=====================================================================================
* compile:
* gcc -g usb.c -o usb_sleep.exe -DSLEEP -D_GNU_SOURCE
* gcc -g usb.c -o usb.exe -D_GNU_SOURCE
*
*
=====================================================================================
*/
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
int
main()
{
char *dev = "/dev/ttyUSB0";
//int fd = open(dev, O_RDONLY|O_LARGEFILE/* O_RDWR | O_NOCTTY |
O_NONBLOCK */);
//int fd = open(dev, O_RDWR | O_NOCTTY | O_NONBLOCK);
int fd = open(dev, O_RDWR | O_NOCTTY | O_NDELAY);
while(fd < 0)
{
//fd = open(dev, O_RDONLY|O_LARGEFILE/* O_RDWR | O_NOCTTY |
O_NONBLOCK */);
//fd = open(dev, O_RDWR | O_NOCTTY | O_NONBLOCK);
fd = open(dev, O_RDWR | O_NOCTTY | O_NDELAY);
#ifdef SLEEP
sleep(1);
#endif
}
printf("open tty ok!\n");
char buf[1024];
printf(buf, "at");
int ret = write(fd, buf, strlen(buf));
if(ret < 0){
printf("write error:%s\n", strerror(errno));
}
ret = read(fd, buf, sizeof(buf) - 1);
if(ret < 0){
printf("read error:%s\n", strerror(errno));
}
close(fd);
}
reproducing procedure:
1.insmod usbserial.ko ftdi_sio.ko
2.#./usb.exe to run my test program
3.plug USB modem in and the dmesg about ftdi_sio stack info above
shows up
what's weird is that if i use the other usb_sleep.exe to test, the
stack info cannot occur, and opens ttyUSB0 fine
PS, my gcc version is:
$gcc -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with:
/var/tmp/portage/sys-devel/gcc-4.1.2/work/gcc-4.1.2/configure
--prefix=/usr --bindir=/usr/i686-pc-linux-gnu/gcc-bin/4.1.2
--includedir=/usr/lib/gcc/i686-pc-linux-gnu/4.1.2/include
--datadir=/usr/share/gcc-data/i686-pc-linux-gnu/4.1.2
--mandir=/usr/share/gcc-data/i686-pc-linux-gnu/4.1.2/man
--infodir=/usr/share/gcc-data/i686-pc-linux-gnu/4.1.2/info
--with-gxx-include-dir=/usr/lib/gcc/i686-pc-linux-gnu/4.1.2/include/g++-v4
--host=i686-pc-linux-gnu --build=i686-pc-linux-gnu --disable-altivec
--enable-nls --without-included-gettext --with-system-zlib
--disable-checking --disable-werror --enable-secureplt
--disable-libunwind-exceptions --disable-multilib --enable-libmudflap
--disable-libssp --disable-libgcj --with-arch=i686
--enable-languages=c,c++,treelang,fortran --enable-shared
--enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu
Thread model: posix
gcc version 4.1.2 (Gentoo 4.1.2 p1.0.2)
I've tried to compile newer kernel to check if it has similar
issue(bug info from dmesg), and
the follow is the tested buggy kernel:
2.6.32.58
2.6.35.13
3.2.11
all of them are downloaded from main page of kernel.org
Regards,
Ken Huang
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