Messages in this thread | | | Date | Thu, 24 Sep 2020 17:53:43 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [PATCH printk 3/5] printk: use buffer pool for sprint buffers |
| |
On (20/09/24 10:45), Petr Mladek wrote: > On Thu 2020-09-24 14:40:58, Sergey Senozhatsky wrote: > > On (20/09/23 17:11), Petr Mladek wrote: > > > > > > AFAIK, there is one catch. We need to use va_copy() around > > > the 1st call because va_format can be proceed only once. > > > > > > > Current printk() should be good enough for reporting, say, "Kernel > > stack overflow" errors. Is extra pressure that va_copy() adds something > > that we need to consider? > > The thing is that vsprintf() traverses the arguments using va_arg(). > It modifies internal values so that the next va_arg() will read > the next value.
Yes, I understand the purpose of va_copy(). I'm asking if we are always on the safe side doing va_copy for every printk (+ potential recursive va_copy-s).
> If we want to call vsprintf() twice then we need to reset the internal > va_list states. My understanding is that va_copy() is the only legal > way when we are already nested inside va_start()/va_end().
Yes, it is. My question is a bit different.
-ss
| |