Re: [PATCH 1/1] cciss: fix regression, sysfs symlink missing

[Alan D. Brunelle]

Mike Miller wrote:
> Patch 1 of 1
> 
> This patch fixes a regression where the device symlink to the pci address is
> not created. Offending commit 6ae5ce8e8d4de666f31286808d2285aa6a50fa40,
> cciss: rmove redundant code.
> 
> Please consider this for inclusion.
> 
> signed-off-by: Mike Miller <mike.miller@xxxxxx>
> 
> diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
> index 1e1f915..44fb98e 100644
> --- a/drivers/block/cciss.c
> +++ b/drivers/block/cciss.c
> @@ -1365,6 +1365,7 @@ static void cciss_add_disk(ctlr_info_t *h, struct gendisk *disk,
>  	disk->first_minor = drv_index << NWD_SHIFT;
>  	disk->fops = &cciss_fops;
>  	disk->private_data = &h->drv[drv_index];
> +	disk->driverfs_dev = &(hba[drv_index]->pdev->dev);
>  
>  	/* Set up queue information */
>  	blk_queue_bounce_limit(disk->queue, h->pdev->dma_mask);
> --
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> 

Hi Mike -

I'm finding that

hba[drv_index]

(for any index) is NULL, and I'm getting the NULL pointer dereference
bug shown below.

I'm using Linus' tree up to:

6c5e51dae2c37127e00be392f40842e08077e96a

patched with your patch here.

To determine this, I simply did:

        if (hba[drv_index] == NULL)
                printk("cciss_add_disk(%d) hba null\n", drv_index);
        else if (hba[drv_index]->pdev == NULL)
                printk("cciss_add_disk(%d) hba->pdev null\n", drv_index);
        else
                disk->driverfs_dev = &(hba[drv_index]->pdev->dev);

and find:

cciss_add_disk(1) hba null
cciss_add_disk(2) hba null
cciss_add_disk(3) hba null
cciss_add_disk(4) hba null
cciss_add_disk(5) hba null
cciss_add_disk(6) hba null
cciss_add_disk(7) hba null

in the dmesg log after boot...

Regards,
Alan

BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
IP: [<ffffffffa00ae506>] cciss_add_disk+0x80/0x10f [cciss]
PGD 87b069067 PUD 87b06a067 PMD 0
Oops: 0000 [1] SMP
CPU 0
Modules linked in: cciss(+) sd_mod scsi_mod ext3 jbd uhci_hcd ohci_hcd
ehci_hcd
Pid: 1852, comm: insmod Not tainted 2.6.27 #1
RIP: 0010:[<ffffffffa00ae506>]  [<ffffffffa00ae506>]
cciss_add_disk+0x80/0x10f [cciss]
RSP: 0018:ffff88087b03fc38  EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff88087b005000 RCX: 00000000fffffffb
RDX: ffff88087b03f967 RSI: 00000000ffffffff RDI: ffff88087b0027c0
RBP: ffff88087b140000 R08: 0000000000000000 R09: ffff88087b03f900
R10: 0000000000000000 R11: ffffffffa00ae74a R12: 0000000000000001
R13: ffff88087b140000 R14: ffff88087b140040 R15: ffff88087b140000
FS:  0000000000682850(0063) GS:ffffffff80703a80(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000020 CR3: 000000087b010000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process insmod (pid: 1852, threadinfo ffff88087b03e000, task
ffff88087b94c2c0)
Stack:  ffff88087b980680 ffff88087bc45170 ffff88087b1400f0 ffff88107cf88000
 ffff88087bc45140 ffffffffa00af3da ffff880800000083 0000000000000000
 0000000100000040 0000000800000000 ffff88087b110000 00000001802d0c5d
Call Trace:
 [<ffffffffa00af3da>] ? rebuild_lun_table+0x5b8/0x6c7 [cciss]
 [<ffffffffa00b188d>] ? cciss_init_one+0x988/0xb3d [cciss]
 [<ffffffff8032e84c>] ? pci_device_probe+0xb6/0x105
 [<ffffffff80398ae0>] ? driver_probe_device+0xd0/0x14d
 [<ffffffff80398ba3>] ? __driver_attach+0x46/0x6d
 [<ffffffff80398b5d>] ? __driver_attach+0x0/0x6d
 [<ffffffff80398283>] ? bus_for_each_dev+0x44/0x6f
 [<ffffffff803986b9>] ? bus_add_driver+0xb4/0x203
 [<ffffffff80398dff>] ? driver_register+0x8d/0x101
 [<ffffffffa00c3000>] ? cciss_init+0x0/0x2e [cciss]
 [<ffffffff8032eaab>] ? __pci_register_driver+0x5a/0x8b
 [<ffffffffa00c3000>] ? cciss_init+0x0/0x2e [cciss]
 [<ffffffff80209041>] ? _stext+0x41/0x110
 [<ffffffff8025428f>] ? sys_init_module+0x9e/0x1ab
 [<ffffffff8020be0b>] ? system_call_fastpath+0x16/0x1b


Code: 03 44 89 e0 4d 63 e4 4d 89 e6 c1 e0 04 49 c1 e6 06 89 43 04 4b 8d
84 2e 90 00 00 00 4d 01 ee 48 89 43 48 4a 8b 04 e5 80 13 0c a0 <48> 8b
40 20 48 83 e8 80 48 89 43 60 49 8b 45 20 48 8b 70 58 e8
RIP  [<ffffffffa00ae506>] cciss_add_disk+0x80/0x10f [cciss]
 RSP <ffff88087b03fc38>
CR2: 0000000000000020
---[ end trace 12ad011b32e7c85e ]---

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