BUG: scheduling while atomic

Hi Arun,

On Wed, Apr 18, 2012 at 1:08 AM, Arun KS [off-list ref] wrote:

Hi Dave,

Thanks for your reply.

On Wed, Apr 18, 2012 at 1:01 PM, Dave Hylands [off-list ref] wrote:

quoted

Hi Arun,

On Tue, Apr 17, 2012 at 11:44 PM, Arun KS [off-list ref] wrote:

quoted

Hello Guys,

System is working normal after this BUG.
PC is at 0x400b4614, probably a mmaped address.

Just wondering how can this BUG happen when a process is running in user
space.

Can it be something like this
1) enter to kernel from userspace through some system call.
2) kernel disables the interrupt and return to user space.

Don't do that

I don't do that. This scenario mentioned is a just a wild guess.

quoted

quoted

3) and now it can happen in user space?

Because something in userspace made a blocking call which would cause
a context switch to occur and your driver erroneously left interrupts
disabled.

In that case, my system should have been unstable afterwards if interrupts
are left disabled. But that is not happening.

If we return to user space with interrupts disabled, can we switch back
again to kernel using a system cal(because interrupts are already disabled)?

As long as you don't do anything which would need to block.

A buggy driver could also interrupt user-code (hardware interrupt) and
disable interrupts and not re-enable them.

-- 
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com