Messages in this thread | | | Date | Wed, 13 Apr 2011 14:52:41 +0200 | Subject | Re: Call of /proc/ entry troughs a kernel bug | From | Miguel Ojeda <> |
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On Wed, Apr 13, 2011 at 2:36 PM, limp <johnkyr83@hotmail.com> wrote: > Hi all, > > I am using a 2.6.31.8 vanilla kernel on a Debian "lenny" distro. > > What I am trying to do is to create a module that creates a pseudo-file > named '/proc/myfile' which prints some messages on the screen. > > My module compiles correctly and I am also inserting it (insmod) into the > kernel without a problem. The problem occurs when I am trying to call it > like that: > > $ cat /proc/myfile > > When I am doing that, I am getting the following output: > > > Installing 'myfile' module > BUG: unable to handle kernel paging request at 5a58e10f > IP: [<5a58e10f>] 0x5a58e10f > *pde = 00000000 > Oops: 0000 [#1] PREEMPT > last sysfs file: > /sys/devices/pci0000:00/0000:00:1d.2/usb3/3-2/3-2:1.0/host2/target2:0:0/2:0: > 0:0/block/sdb/size > Modules linked in: myfile > > Pid: 2150, comm: cat Not tainted (2.6.31.8 #3) 986LCD-M/mITX > EIP: 0060:[<5a58e10f>] EFLAGS: 00210206 CPU: 0 > EIP is at 0x5a58e10f > EAX: d25c6ad8 EBX: 00000000 ECX: 00000006 EDX: d4652d00 > ESI: d443c2a0 EDI: d44a67a0 EBP: d4619e8c ESP: d4619e68 > DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068 > Process cat (pid: 2150, ti=d4618000 task=d463c9c0 task.ti=d4618000) > Stack: > c10cfd2d d4652d00 d25c6ad8 5a58e10f 00000004 00000020 00000000 d4652d00 > <0> d25c6ad8 d4619eac c1095f99 de92a200 d25b2c00 c114f913 d4652d00 d4619ef8 > <0> d4619ef8 d4619ec8 c1096120 d4652d00 c10cfc0f d4652380 00000000 d4619ef8 > Call Trace: > [<c10cfd2d>] ? proc_reg_open+0x11e/0x1aa > [<c1095f99>] ? __dentry_open+0x155/0x243 > [<c114f913>] ? security_inode_permission+0x1e/0x20 > [<c1096120>] ? nameidata_to_filp+0x2b/0x42 > [<c10cfc0f>] ? proc_reg_open+0x0/0x1aa > [<c10a0c94>] ? do_filp_open+0x3e4/0x75b > [<c10a106f>] ? getname+0x20/0xb6 > [<c10a9b8a>] ? alloc_fd+0xdb/0xee > [<c1095d4d>] ? do_sys_open+0x4a/0xe2 > [<c1095e27>] ? sys_open+0x1e/0x26 > [<c1002a30>] ? sysenter_do_call+0x12/0x22 > Code: Bad EIP value. > EIP: [<5a58e10f>] 0x5a58e10f SS:ESP 0068:d4619e68 > CR2: 000000005a58e10f > ---[ end trace dcbe10409eb0e88c ]--- > > > The code of my module is the following: > > > #include <linux/module.h> // for init_module() > #include <linux/proc_fs.h> // for proc_create_data() > > char modname[] = "myfile"; > > int my_get_info( char *buf, char **start, off_t off, int count ) > { > int len = 1; > printk( "I am inside my get info function! \n"); > return len; > } > > static int __init my_init( void ) > { > printk( "<1>\nInstalling \'%s\' module\n", modname ); > proc_create_data( modname, 0, NULL, my_get_info, NULL ); > return 0; > } > > static void __exit my_exit(void ) > { > remove_proc_entry( modname, NULL ); > printk( "<1>Removing \'%s\' module\n", modname ); > } > > module_init( my_init ); > module_exit( my_exit ); > > MODULE_LICENSE("GPL"); > > > Any help on trying to debug this problem will be greatly appreciated.
Review proc_create_data(), it does not work like that. Try not to follow old tutorials.
> > King regards, > > John K. > > -- > 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/ > -- 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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