It is true that we should probably check the return value of the
allocator, however
the allocator should have never have failed to begin with. My recollection
is that it
is just a thin wrapper around kmalloc(). Perhaps the system didn't have
any DMA
pages available. Was the system really really busy at the time this error
came up?
Someday either myself of someone else needs to eliminate
scsi_init_malloc altogether.
It is redundant now, and can simply be replaced by kmalloc() or
__get_dma_pages(). It
was required a long time ago (in the 1.N series??) since at that time the
memory manager
wasn't initialized at the time that SCSI was initialized.
-Eric
-----Original Message-----
From: Thorsten Knabe <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Date: Wednesday, June 09, 1999 4:58 AM
Subject: PROBLEM: Obvious(?) bug in scsi.c
[1.] One line summary of the problem:
Obvious(?) bug in scsi.c
[2.] Full description of the problem/report:
The following Oops was raised by issueing the command
echo "scsi add-single-device 0 0 1 0" >/proc/scsi/scsi
Afterwards the shell hung in D state.
[3.] Keywords (i.e., modules, networking, kernel):
scsi
[4.] Kernel version (from /proc/version):
Linux version 2.2.9 (root@tek01) (gcc version 2.7.2.3)
[5.] Output of Oops.. message (if applicable) with symbolic information
resolved (see Documentation/oops-tracing.txt)
kernel: Oops: 0002
kernel: CPU: 0
kernel: EIP: 0010:[<d0945594>] (scan_scsis+84)
kernel: EFLAGS: 00010246
kernel: eax: 00000000 ebx: 00000001 ecx: 00000046 edx: 00000000
kernel: esi: cfc40000 edi: 00000000 ebp: 00000001 esp: ce5addd4
kernel: ds: 0018 es: 0018 ss: 0018
kernel: Process bash (pid: 26452, process nr: 52, stackpage=ce5ad000)
kernel: Stack: 00000000 00000001 c01cff18 fffffff8 6f686365 00000000
61206900
732d6401
kernel: 6c676e00 65642d65 65636976 30203020 30203120 2f3e2022
636f7270
ffffffff
kernel: c01eaceb d094c867 00000002 ce5adfc4 ce5adee8 00000038
ce5ade3c
c01c2b90
kernel: Call Trace: [<d094c867>] [<c01c2b90>] [<c0128aa2>]
[<c012ee93>] [<c01add9f>] [<d094c84b>] [<c010e98e>]
kernel: [<c010f037>] [<c01118be>] [<d094c84b>]
[<d094745f>] [<d094c84c>] [<d09474f4>] [<d094954e>] [<c0147576>]
kernel: [<c0147508>] [<c0122bb0>] [<c0107a54>]
kernel: Code: f3 ab 6a 08 6a 58 e8 a5 19 00 00 89 c7 89 7c 24 34 83 c4 08
[6.] A small shell script or example program which triggers the
problem (if possible)
not (easily) reproduceable
[7.] Environment
SCSI stuff is build as module and has been loaded successfully loaded at
boot time. Other stuff seems to be irrelevant.
[X.] Other notes, patches, fixes, workarounds:
The Oops occured at scan_scsis+84 (d0945594), which seems to match the
following code in drivers/scsi/scsi.c:
static void scan_scsis (struct Scsi_Host *shpnt,
unchar hardcoded,
unchar hchannel,
unchar hid,
unchar hlun)
{
int channel;
int dev;
int lun;
int max_dev_lun;
Scsi_Cmnd * SCpnt;
unsigned char * scsi_result;
unsigned char scsi_result0[256];
Scsi_Device * SDpnt;
Scsi_Device * SDtail;
int sparse_lun;
SCpnt = (Scsi_Cmnd *) scsi_init_malloc (sizeof (Scsi_Cmnd), GFP_ATOMIC |
GFP_D
MA);
memset (SCpnt, 0, sizeof (Scsi_Cmnd)); /* Oops */
SDpnt = (Scsi_Device *) scsi_init_malloc (sizeof (Scsi_Device),
GFP_ATOMIC);
memset (SDpnt, 0, sizeof (Scsi_Device));
/* Make sure we have something that is valid for DMA purposes */
scsi_result = ( ( !shpnt->unchecked_isa_dma )
? &scsi_result0[0] : scsi_init_malloc (512, GFP_DMA));
Obviously scsi_init_malloc has failed and returned NULL. Then trying to
clear the the memory block using memset caused the Oops. Maybe we should
check if allocation succeeded before we clear the allocated area. ;) Btw.
memsetting the allocated area seems to be redundant. It is already cleard
by scsi_init_malloc.
Regards
Thorsten
I�m not subscribed to linux-scsi, so please CC me.
--
E-Mail: [EMAIL PROTECTED]
___ WWW: http://www.student.informatik.tu-darmstadt.de/~tek
| | / ICQ: 5472045
|horsten |/\nabe
-
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to [EMAIL PROTECTED]
-
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to [EMAIL PROTECTED]
