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From: Saeed Mahameed <saeed@kernel.org>
To: Vladimir Oltean <olteanv@gmail.com>
Cc: "David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	netdev@vger.kernel.org, Andrew Lunn <andrew@lunn.ch>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Stephen Hemminger <stephen@networkplumber.org>,
	Eric Dumazet <edumazet@google.com>,
	George McCollister <george.mccollister@gmail.com>,
	Oleksij Rempel <o.rempel@pengutronix.de>,
	Jay Vosburgh <j.vosburgh@gmail.com>,
	Veaceslav Falico <vfalico@gmail.com>,
	Andy Gospodarek <andy@greyhouse.net>,
	Arnd Bergmann <arnd@arndb.de>, Taehee Yoo <ap420073@gmail.com>,
	Jiri Pirko <jiri@resnulli.us>, Florian Westphal <fw@strlen.de>,
	Nikolay Aleksandrov <nikolay@nvidia.com>,
	Pravin B Shelar <pshelar@ovn.org>,
	Sridhar Samudrala <sridhar.samudrala@intel.com>
Subject: Re: [PATCH v6 net-next 11/15] net: catch errors from dev_get_stats
Date: Mon, 11 Jan 2021 15:51:39 -0800	[thread overview]
Message-ID: <6a6f5e835255a196f461b0e63a68b9bfa576ca1f.camel@kernel.org> (raw)
In-Reply-To: <20210111231535.lfkv7ggjzynbiicc@skbuf>

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.oltean@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


  reply	other threads:[~2021-01-12  0:34 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-09 17:26 [PATCH v6 net-next 00/15] Make .ndo_get_stats64 sleepable Vladimir Oltean
2021-01-09 17:26 ` [PATCH v6 net-next 01/15] net: mark dev_base_lock for deprecation Vladimir Oltean
2021-01-09 17:26 ` [PATCH v6 net-next 02/15] net: introduce a mutex for the netns interface lists Vladimir Oltean
2021-01-09 17:26 ` [PATCH v6 net-next 03/15] net: procfs: hold netif_lists_lock when retrieving device statistics Vladimir Oltean
2021-01-11 23:46   ` Saeed Mahameed
2021-01-12 13:44     ` Vladimir Oltean
2021-01-12 20:06       ` Saeed Mahameed
2021-01-09 17:26 ` [PATCH v6 net-next 04/15] net: sysfs: don't hold dev_base_lock while " Vladimir Oltean
2021-01-09 17:26 ` [PATCH v6 net-next 05/15] s390/appldata_net_sum: hold the netdev lists lock when " Vladimir Oltean
2021-01-09 17:26 ` [PATCH v6 net-next 06/15] parisc/led: " Vladimir Oltean
2021-01-09 17:26 ` [PATCH v6 net-next 07/15] net: remove return value from dev_get_stats Vladimir Oltean
2021-01-11 22:08   ` Saeed Mahameed
2021-01-09 17:26 ` [PATCH v6 net-next 08/15] net: allow ndo_get_stats64 to return an int error code Vladimir Oltean
2021-01-11 22:24   ` Saeed Mahameed
2021-01-11 22:43   ` Saeed Mahameed
2021-01-09 17:26 ` [PATCH v6 net-next 09/15] scsi: fcoe: propagate errors from dev_get_stats Vladimir Oltean
2021-01-09 17:26 ` [PATCH v6 net-next 10/15] net: openvswitch: " Vladimir Oltean
2021-01-09 17:26 ` [PATCH v6 net-next 11/15] net: catch " Vladimir Oltean
2021-01-11 22:54   ` Saeed Mahameed
2021-01-11 23:15     ` Vladimir Oltean
2021-01-11 23:51       ` Saeed Mahameed [this message]
2021-01-18 10:31         ` Vladimir Oltean
2021-01-09 17:26 ` [PATCH v6 net-next 12/15] net: openvswitch: ensure dev_get_stats can sleep Vladimir Oltean
2021-01-09 17:26 ` [PATCH v6 net-next 13/15] net: net_failover: ensure .ndo_get_stats64 " Vladimir Oltean
2021-01-09 17:26 ` [PATCH v6 net-next 14/15] net: bonding: " Vladimir Oltean
2021-01-11 23:38   ` Saeed Mahameed
2021-01-12 14:37     ` Vladimir Oltean
2021-01-12 20:10       ` Saeed Mahameed
2021-01-13  2:00         ` Jay Vosburgh
2021-01-09 17:26 ` [PATCH v6 net-next 15/15] net: mark ndo_get_stats64 as being able to sleep Vladimir Oltean

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