On (06/20/18 12:38), Linus Torvalds wrote: > On Wed, Jun 20, 2018 at 11:50 AM Sergey Senozhatsky > <sergey.senozhatsky.work@xxxxxxxxx> wrote: > > > > It's not UART on its own that immediately calls into printk(), that would > > be trivial to fix, it's all those subsystems that serial console driver > > can call into. > > We already have the whole PRINTK_SAFE_CONTEXT_MASK model that only > adds it to a secondary buffer if you get recursion. Why isn't that > triggering? That's the whole point of it. Linus, Alan, Steven, are you on board with the patch set? What shall I do to improve it? PRINTK_SAFE_CONTEXT_MASK is what we answer nowadays when someone says "printk causes deadlocks". We really can't remove all printk-s that can cause uart->...->printk->uart recursion, and the only other option is to use spin_trylock on uart_port->lock in every driver and discard con->write() if we see that we have re-entered uart. I'd rather use per-CPU printk_safe buffer in this case. -ss -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
