RE: [RFC][PATCH v3 2/3] Skip spin_locks in panic case and addWARN_ON()

[Luck, Tony]

> if (reason == KMSG_DUMP_PANIC) {
> 	if(is_spin_locked(&psinfo->buf_lock))
> 		pr_err("lock is taken.\n");
> else {
> 	spin_lock_irqsave(&psinfo->buf_lock, flags);
> }
>
> However, this won't work for this reason.
>  - printk() must not be called in serialized path because deadlock of logbuf_lock may cause.

There is also the issue that kmsg has already computed the addresses
of useful pieces in __log_buf at this point - so any printk() we
add here is not going to be saved into pstore.  So a user relying
on pstore to see what happened, won't see any messages we add here.

-Tony
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