From: Vladimir Oltean <olteanv@gmail.com>
To: "David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>
Cc: 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>,
Saeed Mahameed <saeedm@nvidia.com>
Subject: [PATCH v6 net-next 04/15] net: sysfs: don't hold dev_base_lock while retrieving device statistics
Date: Sat, 9 Jan 2021 19:26:13 +0200 [thread overview]
Message-ID: <20210109172624.2028156-5-olteanv@gmail.com> (raw)
In-Reply-To: <20210109172624.2028156-1-olteanv@gmail.com>
From: Vladimir Oltean <vladimir.oltean@nxp.com>
In the effort of making .ndo_get_stats64 be able to sleep, we need to
ensure the callers of dev_get_stats do not use atomic context.
I need to preface this by saying that I have no idea why netstat_show
takes the dev_base_lock rwlock. Two things can be observed:
(a) it does not appear to be due to dev_isalive requiring it for some
reason, because broadcast_show() also calls dev_isalive() and has
had no problem existing since the beginning of git.
(b) the dev_get_stats function definitely does not need dev_base_lock
protection either. In fact, holding the dev_base_lock is the entire
problem here, because we want to make dev_get_stats sleepable, and
holding a rwlock gives us atomic context.
So since no protection seems to be necessary, just run unlocked while
retrieving the /sys/class/net/eth0/statistics/* values.
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
Changes in v6:
None.
Changes in v5:
None.
Changes in v4:
None.
Changes in v3:
None.
Changes in v2:
None.
net/core/net-sysfs.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index daf502c13d6d..8604183678fc 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -585,14 +585,13 @@ static ssize_t netstat_show(const struct device *d,
WARN_ON(offset > sizeof(struct rtnl_link_stats64) ||
offset % sizeof(u64) != 0);
- read_lock(&dev_base_lock);
if (dev_isalive(dev)) {
struct rtnl_link_stats64 temp;
const struct rtnl_link_stats64 *stats = dev_get_stats(dev, &temp);
ret = sprintf(buf, fmt_u64, *(u64 *)(((u8 *)stats) + offset));
}
- read_unlock(&dev_base_lock);
+
return ret;
}
--
2.25.1
next prev parent reply other threads:[~2021-01-09 17:28 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 ` Vladimir Oltean [this message]
2021-01-09 17:26 ` [PATCH v6 net-next 05/15] s390/appldata_net_sum: hold the netdev lists lock " 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
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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