From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: zhe.he@windriver.com
Cc: pmladek@suse.com, sergey.senozhatsky@gmail.com,
rostedt@goodmis.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] printk: Fix unnecessary returning broken pipe error from devkmsg_read
Date: Mon, 23 Sep 2019 19:05:13 +0900 [thread overview]
Message-ID: <20190923100513.GA51932@jagdpanzerIV> (raw)
In-Reply-To: <1568813503-420025-1-git-send-email-zhe.he@windriver.com>
On (09/18/19 21:31), zhe.he@windriver.com wrote:
>
> When users read the buffer from start, there is no need to return -EPIPE
> since the possible overflows will not affect the output.
>
[..]
> - if (user->seq < log_first_seq) {
> + if (user->seq == 0) {
> + user->seq = log_first_seq;
> + } else if (user->seq < log_first_seq) {
> /* our last seen message is gone, return error and reset */
> user->idx = log_first_idx;
> user->seq = log_first_seq;
A tough call.
User-space wants to read messages which are gone: log_first_seq > user->seq.
I think returning EPIPE is sort of appropriate; user-space, possibly,
can printf(stderr, "Some /dev/kmsg messages are gone\n"); or something
like that.
-ss
next prev parent reply other threads:[~2019-09-23 10:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-18 13:31 [PATCH] printk: Fix unnecessary returning broken pipe error from devkmsg_read zhe.he
2019-09-23 10:05 ` Sergey Senozhatsky [this message]
2019-09-23 10:45 ` He Zhe
2019-09-23 11:39 ` Petr Mladek
2019-09-23 14:11 ` He Zhe
2019-09-23 19:58 ` John Ogness
2019-09-24 1:10 ` Sergey Senozhatsky
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