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

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Message-ID: <20181204180612.z4az5yplw5oqb26a@linutronix.de>
Date:   Tue, 4 Dec 2018 19:06:12 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Kees Cook <keescook@...omium.org>
Cc:     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>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] pstore: Convert buf_lock to semaphore

On 2018-12-04 09:23:13 [-0800], Kees Cook wrote:
> Okay, so, if kmsg_dump() uses rcu_read_lock(), that means efi-pstore
> can _never_ sleep, and it's nothing to do with pstore internals. :( I
> guess we just hard-code it, then? And efi-pstore should probably only
> attach to pstore if it has a nonblock implementation (and warn if one
> isn't available).

I was about to suggest that. I am not aware if anything else could use
efi_pstore_write() use that but otherwise you could hardcode it.

> -Kees
> 
Sebastian