linux-kernel - Re: [GIT PULL] gpio: fixes for v6.1-rc8

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Date:   Sun, 4 Dec 2022 12:30:10 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Bartosz Golaszewski <brgl@...ev.pl>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [GIT PULL] gpio: fixes for v6.1-rc8 - take 2

On Sun, Dec 4, 2022 at 12:17 PM Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> And again - if the trylock is there because 'gdev' itself might go
> away at any time and you can't afford to wait on the lock, then it's
> broken regardless (and the above suggestion won't help either)

.. another reason I can see is that you are holding other locks, and
the trylock is either for deadlock avoidance or because the other
locks are spinning locks and you cannot sleep.

But if that's the case, then the trylock is basically a hacky
workaround for broken locking, together with a "I know the only reason
it fails is because we've already entered the shutdown phase".

Again, that kind of hacky thing is not for this late in the rc game.

It might be an acceptable workaround for backporting if it has *huge*
comments about why it's done that way, but it's not acceptable as some
kind of fix without that kind of documentation for why it's done that
hacky way rather than with proper locking.

               Linus