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

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Message-ID: <20200713022558.GC491026@jagdpanzerIV.localdomain>
Date:   Mon, 13 Jul 2020 11:25:58 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Bruno Meneguele <bmeneg@...hat.com>
Cc:     linux-kernel@...r.kernel.org, pmladek@...e.com,
        sergey.senozhatsky@...il.com, torvalds@...ux-foundation.org,
        Jason@...c4.com
Subject: Re: [PATCH v2] doc:kmsg: explictly state the return value in case of
 SEEK_CUR

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>

	-ss