warn-on from nbd in 2.6.28-rc7 from sysfs_add_one()

warn-on from nbd in 2.6.28-rc7 from sysfs_add_one()

[Pavel Machek]

sysfs_add_one() complains about entry already existing.

								Pavel

usb 5-2: uevent
usb 5-2: usb_probe_device
usb 5-2: configuration #1 chosen from 1 choice
usb 5-2: adding 5-2:1.0 (config #1, interface 0)
usb 5-2:1.0: uevent
usbserial_generic 5-2:1.0: usb_probe_interface
usbserial_generic 5-2:1.0: usb_probe_interface - got id
/data/l/linux/drivers/usb/core/inode.c: creating file '003'
usb 5-2: New USB device found, idVendor=0483, idProduct=2016
usb 5-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
usb 5-2: Product: Biometric Coprocessor
usb 5-2: Manufacturer: STMicroelectronics
Failed to execute /tmp/swsusp-init.  Attempting defaults...
hub 2-0:1.0: hub_suspend
usb usb2: bus auto-suspend
usb usb2: suspend_rh
hub 1-0:1.0: hub_suspend
usb usb1: bus auto-suspend
ehci_hcd 0000:00:1d.7: suspend root hub
hub 3-0:1.0: hub_suspend
usb usb3: bus auto-suspend
usb usb3: suspend_rh
hub 4-0:1.0: hub_suspend
usb usb4: bus auto-suspend
usb usb4: suspend_rh
EXT3 FS on sda4, internal journal
Adding 987988k swap on /dev/sda1.  Priority:-1 extents:1 across:987988k
kjournald starting.  Commit interval 5 seconds
EXT3 FS on sda2, internal journal
EXT3-fs: mounted filesystem with ordered data mode.
pcmcia: Detected deprecated PCMCIA ioctl usage from process: hwclock.
pcmcia: This interface will soon be removed from the kernel; please expect breakage unless you upgrade to new tools.
pcmcia: see http://www.kernel.org/pub/linux/utils/kernel/pcmcia/pcmcia.html for details.
iwl3945 0000:03:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17
iwl3945 0000:03:00.0: restoring config space at offset 0x1 (was 0x100102, writing 0x100106)
iwl3945 0000:03:00.0: firmware: requesting iwlwifi-3945-1.ucode
Registered led device: iwl-phy0:radio
Registered led device: iwl-phy0:assoc
Registered led device: iwl-phy0:RX
Registered led device: iwl-phy0:TX
wlan0: direct probe to AP 00:11:2f:0e:95:a0 try 1
wlan0 direct probe responded
wlan0: authenticate with AP 00:11:2f:0e:95:a0
wlan0: authenticated
wlan0: associate with AP 00:11:2f:0e:95:a0
wlan0: RX AssocResp from 00:11:2f:0e:95:a0 (capab=0x401 status=0 aid=1)
wlan0: associated
coda_read_super: Bad mount data
coda_read_super: device index: 0
coda_read_super: rootfid is (01234567.ffffffff.08051a38.00000000)
coda: Unexpected interruption.
Failure of coda_cnode_make for root: error -4
wlan0: deauthenticated
wlan0: direct probe to AP 00:11:2f:0e:95:a0 try 1
wlan0 direct probe responded
wlan0: authenticate with AP 00:11:2f:0e:95:a0
wlan0: authenticated
wlan0: associate with AP 00:11:2f:0e:95:a0
wlan0: RX ReassocResp from 00:11:2f:0e:95:a0 (capab=0x401 status=0 aid=1)
wlan0: associated
wlan0: deauthenticated
wlan0: direct probe to AP 00:11:2f:0e:95:a0 try 1
wlan0 direct probe responded
wlan0: authenticate with AP 00:11:2f:0e:95:a0
wlan0: authenticated
wlan0: associate with AP 00:11:2f:0e:95:a0
wlan0: RX ReassocResp from 00:11:2f:0e:95:a0 (capab=0x401 status=0 aid=1)
wlan0: associated
wlan0: deauthenticated
wlan0: direct probe to AP 00:11:2f:0e:95:a0 try 1
wlan0 direct probe responded
wlan0: authenticate with AP 00:11:2f:0e:95:a0
wlan0: authenticated
wlan0: associate with AP 00:11:2f:0e:95:a0
wlan0: RX ReassocResp from 00:11:2f:0e:95:a0 (capab=0x401 status=0 aid=1)
wlan0: associated
wlan0: deauthenticated
wlan0: direct probe to AP 00:11:2f:0e:95:a0 try 1
wlan0 direct probe responded
wlan0: authenticate with AP 00:11:2f:0e:95:a0
wlan0: authenticated
wlan0: associate with AP 00:11:2f:0e:95:a0
wlan0: RX ReassocResp from 00:11:2f:0e:95:a0 (capab=0x401 status=0 aid=1)
wlan0: associated
CE: hpet increasing min_delta_ns to 15000 nsec
CE: hpet increasing min_delta_ns to 22500 nsec
Clocksource tsc unstable (delta = -63212306 ns)
wlan0: No ProbeResp from current AP 00:11:2f:0e:95:a0 - assume out of range
wlan0: direct probe to AP 00:11:2f:0e:95:a0 try 1
wlan0 direct probe responded
wlan0: authenticate with AP 00:11:2f:0e:95:a0
wlan0: authenticated
wlan0: associate with AP 00:11:2f:0e:95:a0
wlan0: RX ReassocResp from 00:11:2f:0e:95:a0 (capab=0x401 status=0 aid=1)
wlan0: associated
nbd: registered device at major 43
------------[ cut here ]------------
WARNING: at /data/l/linux/fs/sysfs/dir.c:462 sysfs_add_one+0x4a/0x50()
sysfs: duplicate filename 'pid' can not be created
Modules linked in: nbd
Pid: 8280, comm: nbd-client Not tainted 2.6.28-rc7 #422
Call Trace:
 [<c022e8d6>] warn_slowpath+0x76/0x90
 [<c024e3d1>] __lock_acquire+0x181/0x930
 [<c024e3d1>] __lock_acquire+0x181/0x930
 [<c0298b9f>] ifind+0x8f/0xa0
 [<c07bcff4>] _spin_unlock+0x14/0x20
 [<c02ca151>] sysfs_find_dirent+0x21/0x30
 [<c02ca17c>] __sysfs_add_one+0x1c/0x80
 [<c02ca22a>] sysfs_add_one+0x4a/0x50
 [<c02c9a50>] sysfs_add_file_mode+0x50/0x90
 [<c02c9aa0>] sysfs_add_file+0x10/0x20
 [<f8794e43>] nbd_ioctl+0x423/0x8e0 [nbd]
 [<f87947d0>] nbd_thread+0x0/0x250 [nbd]
 [<c021db8a>] __change_page_attr_set_clr+0xba/0x520
 [<c03c90ea>] delay_tsc+0x2a/0x50
 [<c03c9086>] __delay+0x6/0x10
 [<c03cd72a>] _raw_spin_lock+0xfa/0x190
 [<c021db8a>] __change_page_attr_set_clr+0xba/0x520
 [<c03ba15a>] __blkdev_driver_ioctl+0x7a/0x90
 [<c03ba229>] blkdev_ioctl+0x99/0x9e0
 [<c024e3d1>] __lock_acquire+0x181/0x930
 [<c0267dd6>] get_page_from_freelist+0x266/0x430
 [<c0262a71>] find_get_page+0x91/0xd0
 [<c024e3d1>] __lock_acquire+0x181/0x930
 [<c02629e0>] find_get_page+0x0/0xd0
 [<c0262cbb>] find_lock_page+0x1b/0x60
 [<c02713a0>] __do_fault+0x1a0/0x3c0
 [<c02713a9>] __do_fault+0x1a9/0x3c0
 [<c02ab6a7>] block_ioctl+0x37/0x50
 [<c02ab670>] block_ioctl+0x0/0x50
 [<c0293bbb>] vfs_ioctl+0x2b/0x90
 [<c0293c7c>] do_vfs_ioctl+0x5c/0x490
 [<c02457f6>] down_read_trylock+0x56/0x60
 [<c021cbd0>] do_page_fault+0x0/0x6a0
 [<c021ce4c>] do_page_fault+0x27c/0x6a0
 [<c02940ed>] sys_ioctl+0x3d/0x70
 [<c0203d52>] syscall_call+0x7/0xb
---[ end trace 0cbc102fb0629d93 ]---
nbd: sysfs_create_file failed!<6>nbd-server[8255]: segfault at 7 ip b7e61e97 sp bfc265d0 error 4 in libglib-2.0.so.0.1600.5[b7e37000+b4000]
nbd0: Receive control failed (result -32)
nbd0: queue cleared
nbd-server[8297]: segfault at 7 ip b7f18e97 sp bfbde2c0 error 4 in libglib-2.0.so.0.1600.5[b7eee000+b4000]
nbd0: Receive control failed (result -32)
nbd0: shutting down socket
nbd0: queue cleared
nbd-server[8338]: segfault at 7 ip b7f26e97 sp bfeebdd0 error 4 in libglib-2.0.so.0.1600.5[b7efc000+b4000]
nbd0: Receive control failed (result -32)
nbd0: shutting down socket
nbd0: queue cleared

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Re: warn-on from nbd in 2.6.28-rc7 from sysfs_add_one()

[Pavel Machek]

On Mon 2008-12-08 22:35:42, Pavel Machek wrote:
> 
> sysfs_add_one() complains about entry already existing.

Aha, luckily this is very reproducible:

root@amd:/home/pavel/misc# cat /dev/zero | head -c 10000000 >
/tmp/delme.fstest.fs
root@amd:/home/pavel/misc# nbd-server 9100 -l /anyone.can.connect
/tmp/delme.fstest.fs &
[1] 2360
root@amd:/home/pavel/misc#
** (process:2360): WARNING **: Could not parse config file: Could not
open config file.

[1]+  Done                    nbd-server 9100 -l /anyone.can.connect
/tmp/delme.fstest.fs
root@amd:/home/pavel/misc# sleep 1
sleep 1
root@amd:/home/pavel/misc# sleep 1
root@amd:/home/pavel/misc# nbd-client localhost 9100 /dev/nd0
Error: Can not open NBD: No such device or address
root@amd:/home/pavel/misc# insmod /data/l/b-linux/drivers/block/nbd.ko
nbd: registered device at major 43
root@amd:/home/pavel/misc# nbd-client localhost 9100 /dev/nd0
Negotiation: ..size = 9765KB
bs=1024, sz=9765

^Z
[1]+  Stopped                 nbd-client localhost 9100 /dev/nd0
root@amd:/home/pavel/misc# bg
[1]+ nbd-client localhost 9100 /dev/nd0 &
root@amd:/home/pavel/misc# nbd-client localhost 9100 /dev/nd0
Negotiation: ..size = 9765KB
bs=1024, sz=9765
------------[ cut here ]------------
WARNING: at /data/l/linux/fs/sysfs/dir.c:462 sysfs_add_one+0x4a/0x50()
sysfs: duplicate filename 'pid' can not be created
Modules linked in: nbd
Pid: 2757, comm: nbd-client Not tainted 2.6.28-rc7 #422
Call Trace:

...no, running two clients at the same time is not exactly clever. 

 								Pavel

> wlan0: associated
> nbd: registered device at major 43
> ------------[ cut here ]------------
> WARNING: at /data/l/linux/fs/sysfs/dir.c:462 sysfs_add_one+0x4a/0x50()
> sysfs: duplicate filename 'pid' can not be created
> Modules linked in: nbd
> Pid: 8280, comm: nbd-client Not tainted 2.6.28-rc7 #422
> Call Trace:
>  [<c022e8d6>] warn_slowpath+0x76/0x90
>  [<c024e3d1>] __lock_acquire+0x181/0x930
>  [<c024e3d1>] __lock_acquire+0x181/0x930
>  [<c0298b9f>] ifind+0x8f/0xa0
>  [<c07bcff4>] _spin_unlock+0x14/0x20
>  [<c02ca151>] sysfs_find_dirent+0x21/0x30
>  [<c02ca17c>] __sysfs_add_one+0x1c/0x80
>  [<c02ca22a>] sysfs_add_one+0x4a/0x50
>  [<c02c9a50>] sysfs_add_file_mode+0x50/0x90
>  [<c02c9aa0>] sysfs_add_file+0x10/0x20
>  [<f8794e43>] nbd_ioctl+0x423/0x8e0 [nbd]
>  [<f87947d0>] nbd_thread+0x0/0x250 [nbd]
>  [<c021db8a>] __change_page_attr_set_clr+0xba/0x520
>  [<c03c90ea>] delay_tsc+0x2a/0x50
>  [<c03c9086>] __delay+0x6/0x10
>  [<c03cd72a>] _raw_spin_lock+0xfa/0x190
>  [<c021db8a>] __change_page_attr_set_clr+0xba/0x520
>  [<c03ba15a>] __blkdev_driver_ioctl+0x7a/0x90
>  [<c03ba229>] blkdev_ioctl+0x99/0x9e0
>  [<c024e3d1>] __lock_acquire+0x181/0x930
>  [<c0267dd6>] get_page_from_freelist+0x266/0x430
>  [<c0262a71>] find_get_page+0x91/0xd0
>  [<c024e3d1>] __lock_acquire+0x181/0x930
>  [<c02629e0>] find_get_page+0x0/0xd0
>  [<c0262cbb>] find_lock_page+0x1b/0x60
>  [<c02713a0>] __do_fault+0x1a0/0x3c0
>  [<c02713a9>] __do_fault+0x1a9/0x3c0
>  [<c02ab6a7>] block_ioctl+0x37/0x50
>  [<c02ab670>] block_ioctl+0x0/0x50
>  [<c0293bbb>] vfs_ioctl+0x2b/0x90
>  [<c0293c7c>] do_vfs_ioctl+0x5c/0x490
>  [<c02457f6>] down_read_trylock+0x56/0x60
>  [<c021cbd0>] do_page_fault+0x0/0x6a0
>  [<c021ce4c>] do_page_fault+0x27c/0x6a0
>  [<c02940ed>] sys_ioctl+0x3d/0x70
>  [<c0203d52>] syscall_call+0x7/0xb
> ---[ end trace 0cbc102fb0629d93 ]---
> nbd: sysfs_create_file failed!<6>nbd-server[8255]: segfault at 7 ip b7e61e97 sp bfc265d0 error 4 in libglib-2.0.so.0.1600.5[b7e37000+b4000]
> nbd0: Receive control failed (result -32)
> nbd0: queue cleared
> nbd-server[8297]: segfault at 7 ip b7f18e97 sp bfbde2c0 error 4 in libglib-2.0.so.0.1600.5[b7eee000+b4000]
> nbd0: Receive control failed (result -32)
> nbd0: shutting down socket
> nbd0: queue cleared
> nbd-server[8338]: segfault at 7 ip b7f26e97 sp bfeebdd0 error 4 in libglib-2.0.so.0.1600.5[b7efc000+b4000]
> nbd0: Receive control failed (result -32)
> nbd0: shutting down socket
> nbd0: queue cleared
> 

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(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

do not allow two nbd-clients at same time

[Pavel Machek]

Two nbd-clients at same time are bad idea, and cause WARN_ON from nbd
in 2.6.28-rc7 from sysfs_add_one. This simply prevents that from
happening.

To reproduce:

 cat /dev/zero | head -c 10000000 > /tmp/delme.fstest.fs
 nbd-server 9100 -l /anyone.can.connect > /tmp/delme.fstest.fs &
 sleep 1
 nbd-client localhost 9100 /dev/nd0 &
 nbd-client localhost 9100 /dev/nd0 &

Signed-off-by: Pavel Machek <pavel@suse.cz>

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 78e22d7..0da741e 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -413,6 +410,7 @@ static int nbd_do_it(struct nbd_device *
 		nbd_end_request(req);
 
 	sysfs_remove_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
+	lo->pid = 0;
 	return 0;
 }
 
@@ -627,5 +626,7 @@ static int nbd_ioctl(struct block_device
 		return 0;
 	case NBD_DO_IT:
+		if (lo->pid)
+			return -EBUSY;
 		if (!lo->file)
 			return -EINVAL;
 		thread = kthread_create(nbd_thread, lo, lo->disk->disk_name);

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Re: do not allow two nbd-clients at same time

[Paul Clements]

Pavel Machek wrote:
> Two nbd-clients at same time are bad idea, and cause WARN_ON from nbd
> in 2.6.28-rc7 from sysfs_add_one. This simply prevents that from
> happening.

Thanks for this. But I think we also need the following:

--- drivers/block/nbd.c        2008-12-24 18:26:37.000000000 -0500
+++ drivers/block/nbd.c 2009-01-12 08:50:17.000000000 -0500
@@ -406,6 +406,7 @@ static int nbd_do_it(struct nbd_device *
         ret = sysfs_create_file(&disk_to_dev(lo->disk)->kobj, 
&pid_attr.attr);
         if (ret) {
                 printk(KERN_ERR "nbd: sysfs_create_file failed!");
+               lo->pid = 0;
                 return ret;
         }


To zero out pid in the error case. Otherwise, it looks good.

Thanks,
Paul

Re: do not allow two nbd-clients at same time

[Pavel Machek]

On Mon 2009-01-12 08:55:10, Paul Clements wrote:
> Pavel Machek wrote:
>> Two nbd-clients at same time are bad idea, and cause WARN_ON from nbd
>> in 2.6.28-rc7 from sysfs_add_one. This simply prevents that from
>> happening.
>
> Thanks for this. But I think we also need the following:
>
> --- drivers/block/nbd.c        2008-12-24 18:26:37.000000000 -0500
> +++ drivers/block/nbd.c 2009-01-12 08:50:17.000000000 -0500
> @@ -406,6 +406,7 @@ static int nbd_do_it(struct nbd_device *
>         ret = sysfs_create_file(&disk_to_dev(lo->disk)->kobj,  
> &pid_attr.attr);
>         if (ret) {
>                 printk(KERN_ERR "nbd: sysfs_create_file failed!");
> +               lo->pid = 0;
>                 return ret;
>         }
>
>

Yep, thanks.

> To zero out pid in the error case. Otherwise, it looks good.

Ok, new patch below.
								Pavel

--- 
Two nbd-clients at same time are bad idea, and cause WARN_ON from nbd
in 2.6.28-rc7 from sysfs_add_one. This simply prevents that from
happening.

To reproduce:

 cat /dev/zero | head -c 10000000 > /tmp/delme.fstest.fs
 nbd-server 9100 -l /anyone.can.connect > /tmp/delme.fstest.fs &
 sleep 1
 nbd-client localhost 9100 /dev/nd0 &
 nbd-client localhost 9100 /dev/nd0 &

Signed-off-by: Pavel Machek <pavel@suse.cz>
Acked-by: Paul Clements <paul.clements@steeleye.com>

---
commit 831d1b7c7c5b16b1115d7e08ddf9038704653a03
tree 1ae30466acfb40b88cb7c20613f327c3871274ee
parent 66d8f12491f52e259e42148af099a3fc83425a7b
author Pavel <pavel@amd.ucw.cz> Tue, 13 Jan 2009 09:26:22 +0100
committer Pavel <pavel@amd.ucw.cz> Tue, 13 Jan 2009 09:26:22 +0100

 drivers/block/nbd.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 670e89d..caf6458 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -406,6 +406,7 @@ static int nbd_do_it(struct nbd_device *
 	ret = sysfs_create_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
 	if (ret) {
 		printk(KERN_ERR "nbd: sysfs_create_file failed!");
+		lo->pid = 0;
 		return ret;
 	}
 
@@ -413,6 +414,7 @@ static int nbd_do_it(struct nbd_device *
 		nbd_end_request(req);
 
 	sysfs_remove_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
+	lo->pid = 0;
 	return 0;
 }
 
@@ -646,6 +648,8 @@ static int nbd_ioctl(struct block_device
 		set_capacity(lo->disk, lo->bytesize >> 9);
 		return 0;
 	case NBD_DO_IT:
+		if (lo->pid)
+			return -EBUSY;
 		if (!lo->file)
 			return -EINVAL;
 		thread = kthread_create(nbd_thread, lo, lo->disk->disk_name);

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(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html