From: John Ogness <john.ogness@linutronix.de>
To: Mukesh Ojha <quic_mojha@quicinc.com>, linux-kernel@vger.kernel.org
Cc: rostedt@goodmis.org, senozhatsky@chromium.org, pmladek@suse.com,
Mukesh Ojha <quic_mojha@quicinc.com>
Subject: Re: [PATCH] printk: Fix seq check inside devkmsg_read()
Date: Tue, 18 Jan 2022 14:26:34 +0106 [thread overview]
Message-ID: <874k61xjrx.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <1642505688-1194-1-git-send-email-quic_mojha@quicinc.com>
On 2022-01-18, Mukesh Ojha <quic_mojha@quicinc.com> wrote:
> prb_read_valid() could return a record whose seq number can be
> newer than the requested one. In that case, we allow the reading
> of the data instead of erroring out.
The EPIPE error is intentional. It informs the devkmsg reader that a
record was missed.
For simple readers, like cat(1), this means that the kernel messages
cannot be read completely reliably. We talked about this a while back
[0] because initially I wanted to do what your patch does. In the end it
was agreed that readers of /dev/kmsg must implement EPIPE handling for
missed records.
John Ogness
[0] https://lore.kernel.org/all/87pneiyv12.fsf@linutronix.de
prev parent reply other threads:[~2022-01-18 13:20 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-18 11:34 Mukesh Ojha
2022-01-18 13:20 ` John Ogness [this message]
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