linux-kernel - Re: [PATCH] powerpc/udbg_hvc: retry putc on -EAGAIN

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Date:   Thu, 27 May 2021 13:10:23 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     Nathan Lynch <nathanl@...ux.ibm.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        jirislaby@...nel.org
Subject: Re: [PATCH] powerpc/udbg_hvc: retry putc on -EAGAIN

On Sun, May 23, 2021 at 08:51:09PM +1000, Michael Ellerman wrote:
> Greg KH <gregkh@...uxfoundation.org> writes:
> > On Fri, May 14, 2021 at 04:44:22PM -0500, Nathan Lynch wrote:
> >> hvterm_raw_put_chars() calls hvc_put_chars(), which may return -EAGAIN
> >> when the underlying hcall returns a "busy" status, but udbg_hvc_putc()
> >> doesn't handle this. When using xmon on a PowerVM guest, this can
> >> result in incomplete or garbled output when printing relatively large
> >> amounts of data quickly, such as when dumping the kernel log buffer.
> >> 
> >> Call again on -EAGAIN.
> >> 
> >> Signed-off-by: Nathan Lynch <nathanl@...ux.ibm.com>
> >> ---
> >>  drivers/tty/hvc/hvc_vio.c | 2 +-
> >
> > Subject line does not match up with this file name.
> >
> > Don't you want "tty" and "hvc" in there somewhere?
> 
> It's a powerpc only driver, but I guess the subject should still be
> "tty: hvc: ..." to match convention.
> 
> I was planning to take this via the powerpc tree, but I can drop it if
> you'd rather take it.

No problem, feel free to take it yourself!

greg k-h