netdev - Re: [PATCH 2/2] vhost/scsi: Delete error messages for failed memory allocations in five functions

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Date:   Mon, 22 May 2017 12:23:20 +0100
From:   Stefan Hajnoczi <stefanha@...il.com>
To:     SF Markus Elfring <elfring@...rs.sourceforge.net>
Cc:     kvm@...r.kernel.org, netdev@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        kernel-janitors@...r.kernel.org, Jason Wang <jasowang@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Wolfram Sang <wsa@...-dreams.de>
Subject: Re: [PATCH 2/2] vhost/scsi: Delete error messages for failed memory
 allocations in five functions

On Mon, May 22, 2017 at 12:50:39PM +0200, SF Markus Elfring wrote:
> > Why are you trying to get rid of memory allocation failure messages?
> 
> Do you find information from a Linux allocation failure report sufficient
> for any function implementations here?

If kmalloc() and friends guarantee to print a warning and backtrace on
every allocation failure, then there's no need for error messages in
callers.

That seems like good justification that can go in the commit
description, but I'm not sure if kmalloc() and friends guarantee to show
a message (not just the first time, but for every failed allocation)?

> >> +++ b/drivers/vhost/scsi.c
> >> @@ -417,5 +417,4 @@ vhost_scsi_allocate_evt(struct vhost_scsi *vs,
> >>  	if (!evt) {
> >> -		vq_err(vq, "Failed to allocate vhost_scsi_evt\n");
> > 
> > #define vq_err(vq, fmt, ...) do {                                  \
> >                 pr_debug(pr_fmt(fmt), ##__VA_ARGS__);       \
> >                 if ((vq)->error_ctx)                               \
> >                                 eventfd_signal((vq)->error_ctx, 1);\
> >         } while (0)
> > 
> > You silently dropped the eventfd_signal() call.
> 
> Do you prefer to preserve this special error handling then?

Yes, please leave vq_err() calls.

Stefan

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