Re: recursion handling: Re: [PATCH next v2 3/3] printk: remove logbuf_lock, add syslog_lock

[John Ogness]

On 2020-12-05, Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> wrote:
>> One reason is the use of per-cpu variables. Alternative solution would
>> be to store printk_context into task_struct.
>
> We can keep per-CPU, disable preemption and have counters for
> every context (task, soft/hard irq, NMI). Shouldn't be a problem

These contexts are difficult to track correctly for all the preemption
models (especially when PREEMPT_RT is included). But I will look into
this idea. It would be nice to keep interrupts enabled for that first
vsnprintf() in vprintk_store().

John Ogness