From: Christoph Heiss <c.heiss@proxmox.com>
Cc: Proxmox VE development discussion <pve-devel@lists.proxmox.com>
Subject: Re: [pve-devel] [RFC PATCH common] sysfstools: file_write: properly catch errors
Date: Thu, 17 Oct 2024 12:22:45 +0200 [thread overview]
Message-ID: <tfvglw4ooxd7rmiaj6litl6gkzgfsdu3nsff3ibzl3gd2aog7r@eugcnaxpilzm> (raw)
In-Reply-To: <20240723082925.934603-1-d.csapak@proxmox.com>
Tested this together with the Nvidia vGPU series [0], so please consider
this also:
Tested-by: Christoph Heiss <c.heiss@proxmox.com>
[0] https://lore.proxmox.com/pve-devel/ul3faxwxsi45hk4e44cl2fw4jomoncy53owx3you2wuvo7pymf@dchu53bqfa3p/T/#m2526c3a031aacc2f52080977febd432b4ab2efcf
On Tue, Jul 23, 2024 at 10:29:25AM GMT, Dominik Csapak wrote:
> since `print` is doing buffered IO, we don't always get an error there,
> even if the underlying write does not work.
>
> To properly catch that, do an unbuffered `syswrite` which circumvents
> all buffers and writes directly to the file handle.
>
> We aren't actually interested in the specific error here, but only if
> the write was successful or not.
>
> Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
> ---
>
> Note: this is heavily used when doing PCI passthrough, and it seems we
> did not catch as many errors as we thought. Maybe we should introduce an
> 'noerr' parameter and pass that on all current code paths, since i fear
> that there are many situations where the sysfs write had failed but it
> still works because we ignored it and qemu/the kernel do the right thing
> anyway.
Actually catching errors here is definitely the right thing to do, IMHO.
But as for not breaking existing callers, maybe a `warn` statement would
be sensible?
That way broken call-sites can be caught in the future and fixed as
necessary. So a `noerr` parameter and `warn` if that is unset.
>
> src/PVE/SysFSTools.pm | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/PVE/SysFSTools.pm b/src/PVE/SysFSTools.pm
> index 57f0ac8..8eb9f2e 100644
> --- a/src/PVE/SysFSTools.pm
> +++ b/src/PVE/SysFSTools.pm
> @@ -198,7 +198,7 @@ sub file_write {
> my $fh = IO::File->new($filename, "w");
> return undef if !$fh;
>
> - my $res = print $fh $buf;
> + my $res = defined(syswrite($fh, $buf)) ? 1 : 0;
>
> $fh->close();
>
> --
> 2.39.2
>
>
>
> _______________________________________________
> pve-devel mailing list
> pve-devel@lists.proxmox.com
> https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
>
>
_______________________________________________
pve-devel mailing list
pve-devel@lists.proxmox.com
https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
next prev parent reply other threads:[~2024-10-17 10:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-23 8:29 Dominik Csapak
2024-10-17 10:22 ` Christoph Heiss [this message]
2024-10-24 16:32 ` [pve-devel] applied: " Thomas Lamprecht
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=tfvglw4ooxd7rmiaj6litl6gkzgfsdu3nsff3ibzl3gd2aog7r@eugcnaxpilzm \
--to=c.heiss@proxmox.com \
--cc=pve-devel@lists.proxmox.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.