[uClinux-dev] BUG: scheduling while atomic

[Arnon Meydav]

I ran the ifconfig command from the busybox ash shell, after I found
that other another app that uses the ethernet (and is called from my
init script) produced the same error.
I hope the busybox shell isn't being run from an ISR... ;-)
 - Arnon


________________________________

From: Sven Johnsson [mailto:sven.johnsson at gmail.com] 
Sent: Tuesday, March 20, 2007 16:40
To: uClinux development list
Cc: Arnon Meydav
Subject: Re: [uClinux-dev] BUG: scheduling while atomic


Aron,

It seems like you are accessing ifconfig from an atomic context such as
an interrupt service routine, a kernel timer handler or some code which
is not allowed to sleep. Ifconfig probably uses sleep or some other
scheduling, which is not allowed to run in an atomic context. 
One workaround is to execute a work queue in the atomic context, because
tasks in a work queue are allowed to do scheduling. 
You can find lots of information in the book "Linux Device drivers" by
Rubini. 

Hope this helps.

Regards, 
Sven


2007/3/20, Arnon Meydav <ArnonM at metalinkbb.com>: 

	Hi,
	I am running snapgear-3.4.0 with a preemptive 2.6 kernel, on a
montejade-like board (IXP425 CPU).
	I get the following error message when I run some apps that
access the ethernet device, e.g. ifconfig:
	 
	BUG: scheduling while atomic: ifconfig/0x00000001/802
	[<c0022dc8>] (dump_stack+0x0/0x14) from [<c01dd1c0>]
(schedule+0x60/0x6b8)
	[<c01dd160>] (schedule+0x0/0x6b8) from [<c01de5fc>]
(schedule_timeout+0x8c/0xbc)
	[<c01de570>] (schedule_timeout+0x0/0xbc) from [<bf01c820>]
(ixOsalMutexLock+0x190/0x1b4 [ixp400])
	 r8 = C0E07E0C  r7 = C021D740  r6 = FFFFA7C2  r5 = C0E06000
	 r4 = BF0344B8
	[<bf01c690>] (ixOsalMutexLock+0x0/0x1b4 [ixp400]) from
[<bf00e140>] (ixEthAccMibIIStatsGetClear+0x1)
	 r7 = 00E07E0C  r6 = 05200000  r5 = BF0344C0  r4 = 00000000
	[<bf00e018>] (ixEthAccMibIIStatsGetClear+0x0/0x164 [ixp400])
from [<bf09da28>] (0xbf09da28)
	[<bf09d9d0>] (0xbf09d9d0) from [<c0170e18>]
(dev_seq_show+0x4c/0x134)
	 r6 = C1BAFB60  r5 = C1BAFB60  r4 = C08E4000
	[<c0170dcc>] (dev_seq_show+0x0/0x134) from [<c0098328>]
(seq_read+0x26c/0x3a4)
	 r5 = 0000007B  r4 = C08E4000
	[<c00980bc>] (seq_read+0x0/0x3a4) from [<c0074244>]
(vfs_read+0xc4/0x17c)
	[<c0074180>] (vfs_read+0x0/0x17c) from [<c00745d8>]
(sys_read+0x4c/0x74)
	 r8 = 00000100  r7 = 00000000  r6 = C0E07F78  r5 = C02EF580
	 r4 = C02EF5A0
	[<c007458c>] (sys_read+0x0/0x74) from [<c001dde0>]
(ret_fast_syscall+0x0/0x2c)
	 r8 = C001DF84  r7 = 00000003  r6 = BE9CFB28  r5 = 00000000
	 r4 = 0001A008
	 
	Is this a know issue? Is it OK or a real bug that needs sorting
out?
	(I don't have any experience with the preemptive patch - we've
been using kernel 2.4 till now)
	 
	 
	Thanks, 
	 - Arnon
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