Hi Andy, On Sun, Jun 14, 2020 at 11:43 AM Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote: > On Sun, Jun 14, 2020 at 12:34 PM Andy Shevchenko > <andy.shevchenko@xxxxxxxxx> wrote: > > > > On Sun, Jun 14, 2020 at 12:10 PM Wolfram Sang <wsa@xxxxxxxxxx> wrote: > > > both in the I2C subsystem and also for Renesas drivers I maintain, I am > > > starting to get boilerplate patches doing some pm_runtime_put_* variant > > > because a failing pm_runtime_get is supposed to increase the ref > > > counters? Really? This feels wrong and unintuitive to me. > > > > Yeah, that is a well known issue with PM (I even have for a long time > > a coccinelle script, when I realized myself that there are a lot of > > cases like this, but someone else discovered this recently, like > > opening a can of worms). > > > > > I expect there > > > has been a discussion around it but I couldn't find it. > > > > Rafael explained (again) recently this. I can't find it quickly, unfortunately. > > I _think_ this discussion, but may be it's simple another tentacle of > the same octopus. > https://patchwork.ozlabs.org/project/linux-tegra/patch/20200520095148.10995-1-dinghao.liu@xxxxxxxxxx/ Thanks, hadn't read that one! (so I was still at -1 from http://sweng.the-davies.net/Home/rustys-api-design-manifesto ;-) So "pm_runtime_put_noidle()" is the (definitive?) one to pair with a pm_runtime_get_sync() failure? > > > I wonder why we > > > don't fix the code where the incremented refcount is expected for some > > > reason. > > > > The main idea behind API that a lot of drivers do *not* check error > > codes from runtime PM, so, we need to keep balance in case of > > > > pm_runtime_get(...); > > ... > > pm_runtime_put(...); I've always[*] considered a pm_runtime_get_sync() failure to be fatal (or: cannot happen), and that there's nothing that can be done to recover. Hence I never checked the function's return value. Was that wrong? [*] at least on Renesas SoCs with Clock and/or Power Domains. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
