On Tue, 2021-01-12 at 01:15 +0200, Vladimir Oltean wrote: > 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 <vladimir.olt...@nxp.com> > > > > > > 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? >
both are equivalently concerning. to avoid any user crashes, we can just toss failed netdevs out from the output. > cat /proc/net/dev > Inter- > | Receive | Transmi > t > 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
