On Mon, Jan 11, 2021 at 02:54:50PM -0800, Saeed Mahameed wrote:
> On Sat, 2021-01-09 at 19:26 +0200, Vladimir Oltean wrote:
> > From: Vladimir Oltean <[email protected]>
> >
> > dev_get_stats can now return error codes. Convert all remaining call
> > sites to look at that error code and stop processing.
> >
> > The effects of simulating a kernel error (returning -ENOMEM) upon
> > existing programs or kernel interfaces:
> >
> > - ifconfig and "cat /proc/net/dev" print up until the interface that
> > failed, and there they return:
> > cat: read error: Cannot allocate memory
> >
> > - ifstat and "ip -s -s link show":
> > RTNETLINK answers: Cannot allocate memory
> > Dump terminated
> >
> > Some call sites are coming from a context that returns void (ethtool
> > stats, workqueue context). So since we can't report to the upper
> > layer,
> > do the next best thing: print an error to the console.
> >
>
> another concern, one buggy netdev driver in a system will cause
> unnecessary global failures when reading stats via netlink/procfs for
> all the netdev in a netns, when other drivers will be happy to report.
>
> can't we just show a message in that driver's stats line about the
> occurred err ? and show the normal stats line of all others ?
So you're worried that user space apps won't handle an error code when
reading from a file, but you're not worried that they'll start scraping
junk from procfs when we print this?
cat /proc/net/dev
Inter-| Receive | Transmit
face |bytes packets errs drop fifo frame compressed multicast|bytes
packets errs drop fifo colls carrier compressed
lo: 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0
bond0: Cannot allocate memory
sit0: 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0
