I didn't merge this directly, but instead updated the -rt branches to
-rt9 .. so I got your change that way.
Cheers,
Bruce
On Sun, Sep 29, 2019 at 5:36 AM wrote:
>
> From: He Zhe
>
> This fixes ltp failure,
> kmsg01.c:444: FAIL: read returned: 56: SUCCESS
>
> When user-space wants to read the first message, that is when user->seq
> is 0, and that message has gone, it currently automatically resets
> user->seq to current first seq. This mis-aligns with mainline kernel.
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/ABI/testing/dev-kmsg#n39
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/printk/printk.c#n899
>
> We should inform user-space that what it wants has gone by returning EPIPE
> in such scenario.
>
> Link: https://lore.kernel.org/linux-rt-users/8736gls1aj@linutronix.de/T/#t
>
> Signed-off-by: He Zhe
> ---
> kernel/printk/printk.c | 12
> 1 file changed, 4 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index e3fa33f..58c545a 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -703,14 +703,10 @@ static ssize_t devkmsg_read(struct file *file, char
> __user *buf,
> goto out;
> }
>
> - if (user->seq == 0) {
> - user->seq = seq;
> - } else {
> - user->seq++;
> - if (user->seq < seq) {
> - ret = -EPIPE;
> - goto restore_out;
> - }
> + user->seq++;
> + if (user->seq < seq) {
> + ret = -EPIPE;
> + goto restore_out;
> }
>
> msg = (struct printk_log *)>msgbuf[0];
> --
> 2.7.4
>
--
- Thou shalt not follow the NULL pointer, for chaos and madness await
thee at its end
- "Use the force Harry" - Gandalf, Star Trek II
--
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