user/sven/linux.git/include/uapi/linux/net_dropmon.h, branch v5.5.14

drop_monitor: Make timestamps y2038 safe

2019-08-23T21:58:07Z

Timestamps are currently communicated to user space as 'struct timespec', which is not considered y2038 safe since it uses a 32-bit signed value for seconds. Fix this while the API is still not part of any official kernel release by using 64-bit nanoseconds timestamps instead. Fixes: ca30707dee2b ("drop_monitor: Add packet alert mode") Fixes: 5e58109b1ea4 ("drop_monitor: Add support for packet alert mode for hardware drops") Signed-off-by: Ido Schimmel Acked-by: Neil Horman Signed-off-by: David S. Miller

drop_monitor: Allow user to start monitoring hardware drops

2019-08-17T19:40:08Z

Drop monitor has start and stop commands, but so far these were only used to start and stop monitoring of software drops. Now that drop monitor can also monitor hardware drops, we should allow the user to control these as well. Do that by adding SW and HW flags to these commands. If no flag is specified, then only start / stop monitoring software drops. This is done in order to maintain backward-compatibility with existing user space applications. Signed-off-by: Ido Schimmel Acked-by: Jiri Pirko Signed-off-by: David S. Miller

drop_monitor: Add support for summary alert mode for hardware drops

2019-08-17T19:40:08Z

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 Acked-by: Jiri Pirko Signed-off-by: David S. Miller

drop_monitor: Add support for packet alert mode for hardware drops

2019-08-17T19:40:08Z

In a similar fashion to software drops, extend drop monitor to send netlink events when packets are dropped by the underlying hardware. The main difference is that instead of encoding the program counter (PC) from which kfree_skb() was called in the netlink message, we encode the hardware trap name. The two are mostly equivalent since they should both help the user understand why the packet was dropped. Signed-off-by: Ido Schimmel Acked-by: Jiri Pirko Signed-off-by: David S. Miller

drop_monitor: Expose tail drop counter

2019-08-11T17:53:30Z

Previous patch made the length of the per-CPU skb drop list configurable. Expose a counter that shows how many packets could not be enqueued to this list. This allows users determine the desired queue length. Signed-off-by: Ido Schimmel Signed-off-by: David S. Miller

drop_monitor: Make drop queue length configurable

2019-08-11T17:53:30Z

In packet alert mode, each CPU holds a list of dropped skbs that need to be processed in process context and sent to user space. To avoid exhausting the system's memory the maximum length of this queue is currently set to 1000. Allow users to tune the length of this queue according to their needs. The configured length is reported to user space when drop monitor configuration is queried. Signed-off-by: Ido Schimmel Signed-off-by: David S. Miller

drop_monitor: Add a command to query current configuration

2019-08-11T17:53:30Z

Users should be able to query the current configuration of drop monitor before they start using it. Add a command to query the existing configuration which currently consists of alert mode and packet truncation length. Signed-off-by: Ido Schimmel Signed-off-by: David S. Miller

drop_monitor: Allow truncation of dropped packets

2019-08-11T17:53:30Z

When sending dropped packets to user space it is not always necessary to copy the entire packet as usually only the headers are of interest. Allow user to specify the truncation length and add the original length of the packet as additional metadata to the netlink message. By default no truncation is performed. Signed-off-by: Ido Schimmel Signed-off-by: David S. Miller

drop_monitor: Add packet alert mode

2019-08-11T17:53:30Z

So far drop monitor supported only one alert mode in which a summary of locations in which packets were recently dropped was sent to user space. This alert mode is sufficient in order to understand that packets were dropped, but lacks information to perform a more detailed analysis. Add a new alert mode in which the dropped packet itself is passed to user space along with metadata: The drop location (as program counter and resolved symbol), ingress netdevice and drop timestamp. More metadata can be added in the future. To avoid performing expensive operations in the context in which kfree_skb() is invoked (can be hard IRQ), the dropped skb is cloned and queued on per-CPU skb drop list. Then, in process context the netlink message is allocated, prepared and finally sent to user space. The per-CPU skb drop list is limited to 1000 skbs to prevent exhausting the system's memory. Subsequent patches will make this limit configurable and also add a counter that indicates how many skbs were tail dropped. Signed-off-by: Ido Schimmel Signed-off-by: David S. Miller

drop_monitor: Add alert mode operations

2019-08-11T17:53:30Z

The next patch is going to add another alert mode in which the dropped packet is notified to user space, instead of only a summary of recent drops. Abstract the differences between the modes by adding alert mode operations. The operations are selected based on the currently configured mode and associated with the probes and the work item just before tracing starts. Signed-off-by: Ido Schimmel Signed-off-by: David S. Miller