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authorIdo Schimmel <idosch@mellanox.com>2019-08-17 16:28:15 +0300
committerDavid S. Miller <davem@davemloft.net>2019-08-17 12:40:08 -0700
commitd40e1deb930f4bd51a5214983e50aafc26db686e (patch)
treedee0f882ee543de9150e1ec2bc611c114c89b6cb /net/core
parent5e58109b1ea454b93e455e0e8fc0bc4c226b8c0a (diff)
downloadlinux-d40e1deb930f4bd51a5214983e50aafc26db686e.tar.bz2
drop_monitor: Add support for summary alert mode for hardware drops
In summary alert mode a notification is sent with a list of recent drop reasons and a count of how many packets were dropped due to this reason. To avoid expensive operations in the context in which packets are dropped, each CPU holds an array whose number of entries is the maximum number of drop reasons that can be encoded in the netlink notification. Each entry stores the drop reason and a count. When a packet is dropped the array is traversed and a new entry is created or the count of an existing entry is incremented. Later, in process context, the array is replaced with a newly allocated copy and the old array is encoded in a netlink notification. To avoid breaking user space, the notification includes the ancillary header, which is 'struct net_dm_alert_msg' with number of entries set to '0'. Signed-off-by: Ido Schimmel <idosch@mellanox.com> Acked-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/drop_monitor.c195
1 files changed, 193 insertions, 2 deletions
diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
index 5a950b5af8fd..807c79d606aa 100644
--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -58,9 +58,26 @@ struct net_dm_stats {
struct u64_stats_sync syncp;
};
+#define NET_DM_MAX_HW_TRAP_NAME_LEN 40
+
+struct net_dm_hw_entry {
+ char trap_name[NET_DM_MAX_HW_TRAP_NAME_LEN];
+ u32 count;
+};
+
+struct net_dm_hw_entries {
+ u32 num_entries;
+ struct net_dm_hw_entry entries[0];
+};
+
struct per_cpu_dm_data {
- spinlock_t lock; /* Protects 'skb' and 'send_timer' */
- struct sk_buff *skb;
+ spinlock_t lock; /* Protects 'skb', 'hw_entries' and
+ * 'send_timer'
+ */
+ union {
+ struct sk_buff *skb;
+ struct net_dm_hw_entries *hw_entries;
+ };
struct sk_buff_head drop_queue;
struct work_struct dm_alert_work;
struct timer_list send_timer;
@@ -275,16 +292,189 @@ static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi,
rcu_read_unlock();
}
+static struct net_dm_hw_entries *
+net_dm_hw_reset_per_cpu_data(struct per_cpu_dm_data *hw_data)
+{
+ struct net_dm_hw_entries *hw_entries;
+ unsigned long flags;
+
+ hw_entries = kzalloc(struct_size(hw_entries, entries, dm_hit_limit),
+ GFP_KERNEL);
+ if (!hw_entries) {
+ /* If the memory allocation failed, we try to perform another
+ * allocation in 1/10 second. Otherwise, the probe function
+ * will constantly bail out.
+ */
+ mod_timer(&hw_data->send_timer, jiffies + HZ / 10);
+ }
+
+ spin_lock_irqsave(&hw_data->lock, flags);
+ swap(hw_data->hw_entries, hw_entries);
+ spin_unlock_irqrestore(&hw_data->lock, flags);
+
+ return hw_entries;
+}
+
+static int net_dm_hw_entry_put(struct sk_buff *msg,
+ const struct net_dm_hw_entry *hw_entry)
+{
+ struct nlattr *attr;
+
+ attr = nla_nest_start(msg, NET_DM_ATTR_HW_ENTRY);
+ if (!attr)
+ return -EMSGSIZE;
+
+ if (nla_put_string(msg, NET_DM_ATTR_HW_TRAP_NAME, hw_entry->trap_name))
+ goto nla_put_failure;
+
+ if (nla_put_u32(msg, NET_DM_ATTR_HW_TRAP_COUNT, hw_entry->count))
+ goto nla_put_failure;
+
+ nla_nest_end(msg, attr);
+
+ return 0;
+
+nla_put_failure:
+ nla_nest_cancel(msg, attr);
+ return -EMSGSIZE;
+}
+
+static int net_dm_hw_entries_put(struct sk_buff *msg,
+ const struct net_dm_hw_entries *hw_entries)
+{
+ struct nlattr *attr;
+ int i;
+
+ attr = nla_nest_start(msg, NET_DM_ATTR_HW_ENTRIES);
+ if (!attr)
+ return -EMSGSIZE;
+
+ for (i = 0; i < hw_entries->num_entries; i++) {
+ int rc;
+
+ rc = net_dm_hw_entry_put(msg, &hw_entries->entries[i]);
+ if (rc)
+ goto nla_put_failure;
+ }
+
+ nla_nest_end(msg, attr);
+
+ return 0;
+
+nla_put_failure:
+ nla_nest_cancel(msg, attr);
+ return -EMSGSIZE;
+}
+
+static int
+net_dm_hw_summary_report_fill(struct sk_buff *msg,
+ const struct net_dm_hw_entries *hw_entries)
+{
+ struct net_dm_alert_msg anc_hdr = { 0 };
+ void *hdr;
+ int rc;
+
+ hdr = genlmsg_put(msg, 0, 0, &net_drop_monitor_family, 0,
+ NET_DM_CMD_ALERT);
+ if (!hdr)
+ return -EMSGSIZE;
+
+ /* We need to put the ancillary header in order not to break user
+ * space.
+ */
+ if (nla_put(msg, NLA_UNSPEC, sizeof(anc_hdr), &anc_hdr))
+ goto nla_put_failure;
+
+ rc = net_dm_hw_entries_put(msg, hw_entries);
+ if (rc)
+ goto nla_put_failure;
+
+ genlmsg_end(msg, hdr);
+
+ return 0;
+
+nla_put_failure:
+ genlmsg_cancel(msg, hdr);
+ return -EMSGSIZE;
+}
+
+static void net_dm_hw_summary_work(struct work_struct *work)
+{
+ struct net_dm_hw_entries *hw_entries;
+ struct per_cpu_dm_data *hw_data;
+ struct sk_buff *msg;
+ int rc;
+
+ hw_data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
+
+ hw_entries = net_dm_hw_reset_per_cpu_data(hw_data);
+ if (!hw_entries)
+ return;
+
+ msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+ if (!msg)
+ goto out;
+
+ rc = net_dm_hw_summary_report_fill(msg, hw_entries);
+ if (rc) {
+ nlmsg_free(msg);
+ goto out;
+ }
+
+ genlmsg_multicast(&net_drop_monitor_family, msg, 0, 0, GFP_KERNEL);
+
+out:
+ kfree(hw_entries);
+}
+
static void
net_dm_hw_summary_probe(struct sk_buff *skb,
const struct net_dm_hw_metadata *hw_metadata)
{
+ struct net_dm_hw_entries *hw_entries;
+ struct net_dm_hw_entry *hw_entry;
+ struct per_cpu_dm_data *hw_data;
+ unsigned long flags;
+ int i;
+
+ hw_data = this_cpu_ptr(&dm_hw_cpu_data);
+ spin_lock_irqsave(&hw_data->lock, flags);
+ hw_entries = hw_data->hw_entries;
+
+ if (!hw_entries)
+ goto out;
+
+ for (i = 0; i < hw_entries->num_entries; i++) {
+ hw_entry = &hw_entries->entries[i];
+ if (!strncmp(hw_entry->trap_name, hw_metadata->trap_name,
+ NET_DM_MAX_HW_TRAP_NAME_LEN - 1)) {
+ hw_entry->count++;
+ goto out;
+ }
+ }
+ if (WARN_ON_ONCE(hw_entries->num_entries == dm_hit_limit))
+ goto out;
+
+ hw_entry = &hw_entries->entries[hw_entries->num_entries];
+ strlcpy(hw_entry->trap_name, hw_metadata->trap_name,
+ NET_DM_MAX_HW_TRAP_NAME_LEN - 1);
+ hw_entry->count = 1;
+ hw_entries->num_entries++;
+
+ if (!timer_pending(&hw_data->send_timer)) {
+ hw_data->send_timer.expires = jiffies + dm_delay * HZ;
+ add_timer(&hw_data->send_timer);
+ }
+
+out:
+ spin_unlock_irqrestore(&hw_data->lock, flags);
}
static const struct net_dm_alert_ops net_dm_alert_summary_ops = {
.kfree_skb_probe = trace_kfree_skb_hit,
.napi_poll_probe = trace_napi_poll_hit,
.work_item_func = send_dm_alert,
+ .hw_work_item_func = net_dm_hw_summary_work,
.hw_probe = net_dm_hw_summary_probe,
};
@@ -1309,6 +1499,7 @@ static void net_dm_hw_cpu_data_fini(int cpu)
struct per_cpu_dm_data *hw_data;
hw_data = &per_cpu(dm_hw_cpu_data, cpu);
+ kfree(hw_data->hw_entries);
__net_dm_cpu_data_fini(hw_data);
}