I am now using the filp_open() call in kernel to scan for tape
devices in lieu of chrdev_open()/blkdev_open(), but I have
discovered that calling this api with non-existent devices
appears to result in memory corruption and some nasty oops.
I have attached the code fragment and oops generated by calling
ScanTapeDevices(). This basically works the way Al Viro described,
and I like the auto-probing of the tape device via calls to
filp_open(), which is really slick, if I can just get over
the oops, I think it's there.
Jeff
read enter
Unable to handle kernel paging request at virtual address c4035020
current->tss.cr3 = 03dcc000, %cr3 = 03dcc000
*pde = 03f7a063
*pte = 00000000
Oops: 0000
CPU: 0
EIP: 0010:[sys_mremap+31/884]
EFLAGS: 00010206
eax: ffffffff ebx: c3fefb00 ecx: c023e964 edx: c404d020
esi: c4035020 edi: c404d020 ebp: c3fefb60 esp: c238dd28
ds: 0018 es: 0018 ss: 0018
Process insmod (pid: 658, process nr: 23, stackpage=c238d000)
Stack: c238dd74 c238ddc8 00000020 00000020 ffffffe0 c3fefb6c c238dd50 00000000
00000020 00000004 00000020 c4049c30 c404d020 00000048 00000020 00002000
00000000 00000000 c4049d35 00000000 c025b5a0 c01cb0b1 00000000 0000000d
Call Trace:
[lockd:nlm4_granted_Rea24c726+123124/114388216]
[lockd:nlm4_granted_Rea24c726+136420/114374920]
[lockd:nlm4_granted_Rea24c726+123385/114387955]
[fbcon_cfb24_putc+69/808]
[lockd:nlm4_granted_Rea24c726+143844/114367496]
[lockd:nlm4_granted_Rea24c726+130960/114380380]
[lockd:nlm4_granted_Rea24c726+143588/114367752]
[lockd:nlm4_granted_Rea24c726+127420/114383920]
[lockd:nlm4_granted_Rea24c726+126445/114384895]
[lockd:nlm4_granted_Rea24c726+126268/114385072]
[lockd:nlm4_granted_Rea24c726+121676/114389664]
[lockd:nlm4_granted_Rea24c726+120083/114391257]
[lockd:nlm4_granted_Rea24c726+144284/114367056]
[ide_timer_expiry+172/436]
[lockd:nlm4_granted_Rea24c726+126932/114384408]
[lockd:nlm4_granted_Rea24c726+120004/114391336]
[lockd:nlm4_granted_Rea24c726+127808/114383532]
[lockd:nlm4_granted_Rea24c726+120004/114391336]
[getrusage+263/924]
[lockd:nlm4_granted_Rea24c726+142028/114369312]
[lockd:nlm4_granted_Rea24c726+87236/114424104]
[lockd:nlm4_granted_Rea24c726+120076/114391264]
[do_signal+512/616]
Code: ac ae 75 08 84 c0 75 f8 31 c0 eb 04 19 c0 0c 01 85 c0 75 d9
BYTE *scsi_tape_handles[] =
{
"/dev/st0", "/dev/st1", "/dev/st2", "/dev/st3", "/dev/st4",
"/dev/st5", "/dev/st6", "/dev/st7", "/dev/st8", "/dev/st9",
"/dev/st10", "/dev/st11", "/dev/st12", "/dev/st13", "/dev/st14",
"/dev/st15", "/dev/st16", "/dev/st17", "/dev/st18", "/dev/st19",
"/dev/st20", "/dev/st21", "/dev/st22", "/dev/st23", "/dev/st24",
"/dev/st25", "/dev/st26", "/dev/st27", "/dev/st28", "/dev/st29",
"/dev/st30", "/dev/st31",
0,
};
kdev_t scsi_tape_devs[] =
{
0x0900, 0x0901, 0x0902, 0x0903, 0x0904, 0x0905, 0x0906, 0x0907,
0x0908, 0x0909, 0x090A, 0x090B, 0x090C, 0x090D, 0x090E, 0x090F,
0x0910, 0x0911, 0x0912, 0x0913, 0x0914, 0x0915, 0x0916, 0x0917,
0x0918, 0x0919, 0x091A, 0x091B, 0x091C, 0x091D, 0x091E, 0x091F,
0,
};
BYTE *ide_tape_handles[] =
{
"/dev/ht0", "/dev/ht1", "/dev/ht2", "/dev/ht3", "/dev/ht4",
"/dev/ht5", "/dev/ht6", "/dev/ht7", "/dev/ht8", "/dev/ht9",
"/dev/ht10", "/dev/ht11", "/dev/ht12", "/dev/ht13", "/dev/ht14",
"/dev/ht15", "/dev/ht16", "/dev/ht17", "/dev/ht18", "/dev/ht19",
"/dev/ht20", "/dev/ht21", "/dev/ht22", "/dev/ht23", "/dev/ht24",
"/dev/ht25", "/dev/ht26", "/dev/ht27", "/dev/ht28", "/dev/ht29",
"/dev/ht30", "/dev/ht31", 0
};
kdev_t ide_tape_devs[] =
{
0x3700, 0x3701, 0x3702, 0x3703, 0x3704, 0x3705, 0x3706, 0x3707,
0x3708, 0x3709, 0x370A, 0x370B, 0x370C, 0x370D, 0x370E, 0x370F,
0x3710, 0x3711, 0x3712, 0x3713, 0x3714, 0x3715, 0x3716, 0x3717,
0x3718, 0x3719, 0x371A, 0x371B, 0x371C, 0x371D, 0x371E, 0x371F,
0
};
ULONG max_scsi_tape_devs = sizeof(scsi_tape_devs) / sizeof(kdev_t);
ULONG max_ide_tape_devs = sizeof(ide_tape_devs) / sizeof(kdev_t);
ULONG max_scsi_tape_names = sizeof(scsi_tape_handles) / sizeof(BYTE *);
ULONG max_ide_tape_names = sizeof(ide_tape_handles) / sizeof(BYTE *);
void RemoveTapeDevices(void)
{
register ULONG j;
for (j=0; j < max_scsi_tape_names; j++)
{
if (SystemTape[j])
{
if (SystemTape[j]->filp)
filp_close(SystemTape[j]->filp, NULL);
TRXDRVFree(SystemTape[j]);
SystemTape[j] = 0;
}
}
}
void ScanTapeDevices(void)
{
register ULONG j;
for (j = 0; j < max_scsi_tape_names; j++)
{
if (!SystemTape[j])
{
if (!scsi_tape_devs[j])
break;
SystemTape[j] = (NWTAPE *) TRXDRVAlloc(sizeof(NWTAPE), NWTAPE_TAG);
if (!SystemTape[j])
{
TRXDRVPrint("trxdrv: memory alloc failure in AddTapeDevices\n");
continue;
}
TRXDRVSet(SystemTape[j], 0, sizeof(NWTAPE));
TRXDRVPrint("filp_open %s\n", scsi_tape_handles[j]);
SystemTape[j]->filp = filp_open(scsi_tape_handles[j], O_RDWR, 0600);
if (IS_ERR(SystemTape[j]->filp))
{
if (SystemTape[j])
TRXDRVFree(SystemTape[j]);
SystemTape[j] = 0;
continue;
}
TRXDRVPrint("trxdrv: tape device detected at %s\n",
scsi_tape_handles[j]);
}
}
return;
}
