Re: kernel crash after adding ethernet driver

["pradeep singh" <2500.pradeep@xxxxxxxxx>]

On 5/2/07, Rajat Jain <rajat.noida.india@xxxxxxxxx> wrote:
> Hi Pradeep,
>
> > > > Can you please recheck if you are not holding any spinlocks.Also check
> > > > if you are not doing a memory allocation with spinlock held or in
> > > > interrupt context.May be you are doing something like printk which may
> > > > sleep IMO.Rechcek any methods you are calling which may sleep.
> > >
> > > printk will not sleep. Thus it is safe to call printk from any where
> > > except from very few restricted locations like some scheduler etc.
> >
> > Can you please help me out in understanding why?
> > Printk involves allocating buffer for the message to be printed,
> > right?Which can sleep, isnt it?
> > What am i missing here?
>
> No, printk does not allocate any buffer. printk has a compile time
> circular buffer (log_buf) whose size is determined by compile time
> constant. So what prink does is mere dump the message in this circular
> buffer.
Oh... got it.but this raises a silly doubt for me.
this means you cannot just keep on priniting a lot of data using a
single printk right? May be log_buf has a buffer size limit because it
is a compile time constant.
What am i missing here?

Thanks
~psr

> Thanks,
>
> Rajat


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