linux-kernel - Re: [PATCH v2] doc:kmsg: explictly state the return value in case of SEEK

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Message-ID: <20200713131509.GC20226@alley>
Date:   Mon, 13 Jul 2020 15:15:09 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:     Bruno Meneguele <bmeneg@...hat.com>, linux-kernel@...r.kernel.org,
        torvalds@...ux-foundation.org, Jason@...c4.com
Subject: Re: [PATCH v2] doc:kmsg: explictly state the return value in case of
 SEEK_CUR

On Mon 2020-07-13 11:25:58, Sergey Senozhatsky wrote:
> On (20/07/10 14:44), Bruno Meneguele wrote:
> > The commit 625d3449788f ("Revert "kernel/printk: add kmsg SEEK_CUR
> > handling"") reverted a change done to the return value in case a SEEK_CUR
> > operation was performed for kmsg buffer based on the fact that different
> > userspace apps were handling the new return value (-ESPIPE) in different
> > ways, breaking them.
> > 
> > At the same time -ESPIPE was the wrong decision because kmsg /does support/
> > seek() but doesn't follow the "normal" behavior userspace is used to.
> > Because of that and also considering the time -EINVAL has been used, it was
> > decided to keep this way to avoid more userspace breakage.
> > 
> > This patch adds an official statement to the kmsg documentation pointing to
> > the current return value for SEEK_CUR, -EINVAL, thus userspace libraries
> > and apps can refer to it for a definitive guide on what to expect.
> > 
> > Signed-off-by: Bruno Meneguele <bmeneg@...hat.com>
> 
> Looks good to me,
> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>

The patch is committed in printk/linux.git, branch for-5.9.

Thanks for v2.

Best Regards,
Petr