linux-kernel - Re: [PATCH] pstore: Convert buf

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Message-ID: <20181203111826.ri2csbxs33j34dvo@linutronix.de>
Date:   Mon, 3 Dec 2018 12:18:29 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Kees Cook <keescook@...omium.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        linux-efi <linux-efi@...r.kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] pstore: Convert buf_lock to semaphore

On 2018-12-01 09:42:38 [+0100], Arnd Bergmann wrote:
> You are right that you can't take (or release) a mutex from interrupt
> context. However, I don't think converting a spinlock to a semaphore
> is going to help here either.

you can acquire a semaphore with a try_lock from interrupts context but
you can't do that with a mutex. You can also a acquire a semaphore in
one context and release in another. Not that I'm a fan of those things
but those two are often the reasons why people stick with a semaphore.

I haven't looked a general picture yet, will try to do so later today or
tomorrow.

>         Arnd

Sebastian