phy_speed_down_core provides most of the functionality for
phy_speed_down. It makes use of new helper phy_resolve_min_speed that is
based on the sorting of the settings[] array. In certain cases it may be
helpful to be able to exclude legacy half duplex modes, therefore
prepare phy_resolve_min_speed() for it.

v2:
- rename __phy_speed_down to phy_speed_down_core
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

We will need the functionality of __set_linkmode_max_speed also for
linkmode bitmaps other than phydev->supported. Therefore split it.

v2:
- remove unused parameter from __set_linkmode_max_speed
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

It is enough for caller of devlink_compat_switch_id_get() to hold the net
device to guarantee that devlink port is not destroyed concurrently. Remove
rtnl lock assertion and modify comment to warn user that they must hold
either rtnl lock or reference to net device. This is necessary to
accommodate future implementation of rtnl-unlocked TC offloads driver
callbacks.
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

Daniel Borkmann says:

====================
The following pull-request contains BPF updates for your *net-next* tree.

There is a small merge conflict in libbpf (Cc Andrii so he's in the loop
as well):

        for (i = 1; i <= btf__get_nr_types(btf); i++) {
                t = (struct btf_type *)btf__type_by_id(btf, i);

                if (!has_datasec && btf_is_var(t)) {
                        /* replace VAR with INT */
                        t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
  <<<<<<< HEAD
                        /*
                         * using size = 1 is the safest choice, 4 will be too
                         * big and cause kernel BTF validation failure if
                         * original variable took less than 4 bytes
                         */
                        t->size = 1;
                        *(int *)(t+1) = BTF_INT_ENC(0, 0, 8);
                } else if (!has_datasec && kind == BTF_KIND_DATASEC) {
  =======
                        t->size = sizeof(int);
                        *(int *)(t + 1) = BTF_INT_ENC(0, 0, 32);
                } else if (!has_datasec && btf_is_datasec(t)) {
  >>>>>>> 72ef80b5
                        /* replace DATASEC with STRUCT */

Conflict is between the two commits 1d4126c4 ("libbpf: sanitize VAR to
conservative 1-byte INT") and b03bc685 ("libbpf: convert libbpf code to
use new btf helpers"), so we need to pick the sanitation fixup as well as
use the new btf_is_datasec() helper and the whitespace cleanup. Looks like
the following:

  [...]
                if (!has_datasec && btf_is_var(t)) {
                        /* replace VAR with INT */
                        t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
                        /*
                         * using size = 1 is the safest choice, 4 will be too
                         * big and cause kernel BTF validation failure if
                         * original variable took less than 4 bytes
                         */
                        t->size = 1;
                        *(int *)(t + 1) = BTF_INT_ENC(0, 0, 8);
                } else if (!has_datasec && btf_is_datasec(t)) {
                        /* replace DATASEC with STRUCT */
  [...]

The main changes are:

1) Addition of core parts of compile once - run everywhere (co-re) effort,
   that is, relocation of fields offsets in libbpf as well as exposure of
   kernel's own BTF via sysfs and loading through libbpf, from Andrii.

   More info on co-re: http://vger.kernel.org/bpfconf2019.html#session-2
   and http://vger.kernel.org/lpc-bpf2018.html#session-2

2) Enable passing input flags to the BPF flow dissector to customize parsing
   and allowing it to stop early similar to the C based one, from Stanislav.

3) Add a BPF helper function that allows generating SYN cookies from XDP and
   tc BPF, from Petar.

4) Add devmap hash-based map type for more flexibility in device lookup for
   redirects, from Toke.

5) Improvements to XDP forwarding sample code now utilizing recently enabled
   devmap lookups, from Jesper.

6) Add support for reporting the effective cgroup progs in bpftool, from Jakub
   and Takshak.

7) Fix reading kernel config from bpftool via /proc/config.gz, from Peter.

8) Fix AF_XDP umem pages mapping for 32 bit architectures, from Ivan.

9) Follow-up to add two more BPF loop tests for the selftest suite, from Alexei.

10) Add perf event output helper also for other skb-based program types, from Allan.

11) Fix a co-re related compilation error in selftests, from Yonghong.
====================
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

Fix sparse warning:

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c:3190:5:
 warning: symbol 'hclge_func_reset_sync_vf' was not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

Currently the notifications for deleted snapshots are sent only in case
user deletes a snapshot manually. Send the notifications in case region
is destroyed too.
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

Andrii Nakryiko says:

====================
Now that kernel's BTF is exposed through sysfs at well-known location, attempt
to load it first as a target BTF for the purpose of BPF CO-RE relocations.

Patch #1 is a follow-up patch to rename /sys/kernel/btf/kernel into
/sys/kernel/btf/vmlinux.

Patch #2 adds ability to load raw BTF contents from sysfs and expands the list
of locations libbpf attempts to load vmlinux BTF from.
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Add support for loading kernel BTF from sysfs (/sys/kernel/btf/vmlinux)
as a target BTF. Also extend the list of on disk search paths for
vmlinux ELF image with entries that perf is searching for.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Expose kernel's BTF under the name vmlinux to be more uniform with using
kernel module names as file names in the future.

Fixes: 341dfcf8 ("btf: expose BTF info through sysfs")
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Since the "last_dissection" map holds only the flow keys for the most
recent packet, there is a small race in the skb-less flow dissector
tests if a new packet comes between transmitting the test packet, and
reading its keys from the map. If this happens, the test packet keys
will be overwritten and the test will fail.

Changing the "last_dissection" map to a hash map, keyed on the
source/dest port pair resolves this issue. Additionally, let's clear the
last test results from the map between tests to prevent previous test
cases from interfering with the following test cases.

Fixes: 0905beec ("selftests/bpf: run flow dissector tests in skb-less mode")
Signed-off-by: Petar Penkov <ppenkov@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

bpftool requires libelf, and zlib for decompressing /proc/config.gz.
zlib is a transitive dependency via libelf, and became mandatory since
elfutils 0.165 (Jan 2016). The feature check of libelf is already done
in the elfdep target of tools/lib/bpf/Makefile, pulled in by bpftool via
a dependency on libbpf.a. Add a similar feature check for zlib.
Suggested-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Peter Wu <peter@lekensteyn.nl>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Make .BTF section allocated and expose its contents through sysfs.

/sys/kernel/btf directory is created to contain all the BTFs present
inside kernel. Currently there is only kernel's main BTF, represented as
/sys/kernel/btf/kernel file. Once kernel modules' BTFs are supported,
each module will expose its BTF as /sys/kernel/btf/<module-name> file.

Current approach relies on a few pieces coming together:
1. pahole is used to take almost final vmlinux image (modulo .BTF and
   kallsyms) and generate .BTF section by converting DWARF info into
   BTF. This section is not allocated and not mapped to any segment,
   though, so is not yet accessible from inside kernel at runtime.
2. objcopy dumps .BTF contents into binary file and subsequently
   convert binary file into linkable object file with automatically
   generated symbols _binary__btf_kernel_bin_start and
   _binary__btf_kernel_bin_end, pointing to start and end, respectively,
   of BTF raw data.
3. final vmlinux image is generated by linking this object file (and
   kallsyms, if necessary). sysfs_btf.c then creates
   /sys/kernel/btf/kernel file and exposes embedded BTF contents through
   it. This allows, e.g., libbpf and bpftool access BTF info at
   well-known location, without resorting to searching for vmlinux image
   on disk (location of which is not standardized and vmlinux image
   might not be even available in some scenarios, e.g., inside qemu
   during testing).

Alternative approach using .incbin assembler directive to embed BTF
contents directly was attempted but didn't work, because sysfs_proc.o is
not re-compiled during link-vmlinux.sh stage. This is required, though,
to update embedded BTF data (initially empty data is embedded, then
pahole generates BTF info and we need to regenerate sysfs_btf.o with
updated contents, but it's too late at that point).

If BTF couldn't be generated due to missing or too old pahole,
sysfs_btf.c handles that gracefully by detecting that
_binary__btf_kernel_bin_start (weak symbol) is 0 and not creating
/sys/kernel/btf at all.

v2->v3:
- added Documentation/ABI/testing/sysfs-kernel-btf (Greg K-H);
- created proper kobject (btf_kobj) for btf directory (Greg K-H);
- undo v2 change of reusing vmlinux, as it causes extra kallsyms pass
  due to initially missing  __binary__btf_kernel_bin_{start/end} symbols;

v1->v2:
- allow kallsyms stage to re-use vmlinux generated by gen_btf();
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

/proc/config has never existed as far as I can see, but /proc/config.gz
is present on Arch Linux. Add support for decompressing config.gz using
zlib which is a mandatory dependency of libelf anyway. Replace existing
stdio functions with gzFile operations since the latter transparently
handles uncompressed and gzip-compressed files.

Cc: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Peter Wu <peter@lekensteyn.nl>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

When calling debugfs functions, there is no need to ever check the
return value.  The function can work or not, but the code logic should
never do something different based on this.

Cc: Richard Fontana <rfontana@redhat.com>
Cc: Steve Winslow <swinslow@gmail.com>
Cc: netdev@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

When calling debugfs functions, there is no need to ever check the
return value.  The function can work or not, but the code logic should
never do something different based on this.

Cc: Wei Liu <wei.liu@kernel.org>
Cc: Paul Durrant <paul.durrant@citrix.com>
Cc: xen-devel@lists.xenproject.org
Cc: netdev@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Vivien Didelot says:

====================
net: dsa: mv88e6xxx: prepare Wait Bit operation

The Remote Management Interface has its own implementation of a Wait
Bit operation, which requires a bit number and a value to wait for.

In order to prepare the introduction of this implementation, rework the
code waiting for bits and masks in mv88e6xxx to match this signature.

This has the benefit to unify the implementation of wait routines while
removing obsolete wait and update functions and also reducing the code.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

The mv88e6xxx_smi_direct_wait routine is used to wait on indirect
registers access. It is of no exception and must delay between read
attempts, like other wait routines.
Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The current mv88e6xxx_smi_direct_wait function is only used to check
the 16th bit of the (16-bit) SMI Command register. But the bit shift
operation is not enough if we eventually use this function to check
other bits, thus replace it with a mask.

Fixes: e7ba0fad ("net: dsa: mv88e6xxx: refine SMI support")
Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Now that we have proper Wait Bit and Wait Mask routines, remove the
unused mv88e6xxx_wait routine and its Global 1 and Global 2 variants.

The indirect tables such as the Device Mapping Table or Priority
Override Table make use of an Update bit to distinguish reading (0)
from writing (1) operations. After a write operation occurs, the bit
self clears right away so there's no need to wait on it. Thus keep
things simple and remove the mv88e6xxx_update helper as well.
Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The AVB is not an indirect table using an Update bit, but a unit using
a Busy bit. This means that we must ensure that this bit is cleared
before setting it and wait until it gets cleared again after writing
an operation. Reflect that.
Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Many portions of the driver need to wait until a given bit is set
or cleared. Some busses even have a specific implementation for this
operation. In preparation for such variant, implement a generic Wait
Bit routine that can be used by the driver core functions.

This allows us to get rid of the custom implementations we may find
in the driver. Note that for the EEPROM bits, BUSY and RUNNING bits
are independent, thus it is more efficient to wait independently for
each bit instead of waiting for their mask.
Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The current mv88e6xxx_wait routine is used to wait for a given mask
to be cleared to zero. However in some cases, the driver may have
to wait for a given mask to be of a certain non-zero value.

Thus provide a generic wait mask routine that will be used to implement
the current mv88e6xxx_wait function, and use it to wait for 88E6185
PPU states.
Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The PPU state of 88E6185 can be either "Disabled at Reset" or
"Disabled after Initialization". Because we intentionally clear the
PPU Enabled bit before checking its state, it is safe to wait for the
MV88E6185_G1_STS_PPU_STATE_DISABLED state explicitly instead of waiting
for any state different than MV88E6185_G1_STS_PPU_STATE_POLLING.
Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

rtl8169_free_rx_databuff is used in only one place, so let's inline it.
We can improve the loop because rtl8169_init_ring zero's RX_databuff
before calling rtl8169_rx_fill, and rtl8169_rx_fill fills
Rx_databuff starting from index 0.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Heiner Kallweit says:

====================
net: phy: realtek: add support for integrated 2.5Gbps PHY in RTL8125

This series adds support for the integrated 2.5Gbps PHY in RTL8125.
First three patches add necessary functionality to phylib.

Changes in v2:
- added patch 1
- changed patch 4 to use a fake PHY ID that is injected by the
  network driver. This allows to use a dedicated PHY driver.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

This adds support for the integrated 2.5Gbps PHY in Realtek RTL8125.
Advertisement of 2.5Gbps mode is done via a vendor-specific register.
Same applies to reading NBase-T link partner advertisement.
Unfortunately this 2.5Gbps PHY shares the PHY ID with the integrated
1Gbps PHY's in other Realtek network chips and so far no method is
known to differentiate them. As a workaround use a dedicated fake PHY ID
that is set by the network driver by intercepting the MDIO PHY ID read.

v2:
- Create dedicated PHY driver and use a fake PHY ID that is injected by
  the network driver. Suggested by Andrew Lunn.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add helper function phy_modify_paged_changed, behavios is the same
as for phy_modify_changed.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

The integrated PHY in 2.5Gbps chip RTL8125 is the first (known to me)
PHY that uses standard Clause 22 for all modes up to 1Gbps and adds
2.5Gbps control using vendor-specific registers. To use phylib for
the standard part little extensions are needed:
- Move most of genphy_config_aneg to a new function
  __genphy_config_aneg that takes a parameter whether restarting
  auto-negotiation is needed (depending on whether content of
  vendor-specific advertisement register changed).
- Don't clear phydev->lp_advertising in genphy_read_status so that
  we can set non-C22 mode flags before.

Basically both changes mimic the behavior of the equivalent Clause 45
functions.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Using linkmode_adv_to_mii_adv_t and linkmode_adv_to_mii_ctrl1000_t
allows to simplify the code. In addition avoiding the conversion to
the legacy u32 advertisement format allows to remove the warning.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Suggested-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

Register couple of devlink params, one generic, one driver-specific.
Make the values available over debugfs.

Example:
$ echo "111" > /sys/bus/netdevsim/new_device
$ devlink dev param
netdevsim/netdevsim111:
  name max_macs type generic
    values:
      cmode driverinit value 32
  name test1 type driver-specific
    values:
      cmode driverinit value true
$ cat /sys/kernel/debug/netdevsim/netdevsim111/max_macs
32
$ cat /sys/kernel/debug/netdevsim/netdevsim111/test1
Y
$ devlink dev param set netdevsim/netdevsim111 name max_macs cmode driverinit value 16
$ devlink dev param set netdevsim/netdevsim111 name test1 cmode driverinit value false
$ devlink dev reload netdevsim/netdevsim111
$ cat /sys/kernel/debug/netdevsim/netdevsim111/max_macs
16
$ cat /sys/kernel/debug/netdevsim/netdevsim111/test1
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Ido Schimmel says:

====================
drop_monitor: Capture dropped packets and metadata

So far drop monitor supported only one mode of operation in which a
summary of recent packet drops is periodically sent to user space as a
netlink event. The event only includes the drop location (program
counter) and number of drops in the last interval.

While this mode of operation allows one to understand if the system is
dropping packets, it is not sufficient if a more detailed analysis is
required. Both the packet itself and related metadata are missing.

This patchset extends drop monitor with another mode of operation where
the packet - potentially truncated - and metadata (e.g., drop location,
timestamp, netdev) are sent to user space as a netlink event. Thanks to
the extensible nature of netlink, more metadata can be added in the
future.

To avoid performing expensive operations in the context in which
kfree_skb() is called, the dropped skbs are cloned and queued on per-CPU
skb drop list. The list is then processed in process context (using a
workqueue), where the netlink messages are allocated, prepared and
finally sent to user space.

A follow-up patchset will integrate drop monitor with devlink and allow
the latter to call into drop monitor to report hardware drops. In the
future, XDP drops can be added as well, thereby making drop monitor the
go-to netlink channel for diagnosing all packet drops.

Example usage with patched dropwatch [1] can be found here [2]. Example
dissection of drop monitor netlink events with patched wireshark [3] can
be found here [4]. I will submit both changes upstream after the kernel
changes are accepted. Another change worth making is adding a dropmon
pseudo interface to libpcap, similar to the nflog interface [5]. This
will allow users to specifically listen on dropmon traffic instead of
capturing all netlink packets via the nlmon netdev.

Patches #1-#5 prepare the code towards the actual changes in later
patches.

Patch #6 adds another mode of operation to drop monitor in which the
dropped packet itself is notified to user space along with metadata.

Patch #7 allows users to truncate reported packets to a specific length,
in case only the headers are of interest. The original length of the
packet is added as metadata to the netlink notification.

Patch #8 allows user to query the current configuration of drop monitor
(e.g., alert mode, truncation length).

Patches #9-#10 allow users to tune the length of the per-CPU skb drop
list according to their needs.

Changes since v1 [6]:
* Add skb protocol as metadata. This allows user space to correctly
  dissect the packet instead of blindly assuming it is an Ethernet
  packet

Changes since RFC [7]:
* Limit the length of the per-CPU skb drop list and make it configurable
* Do not use the hysteresis timer in packet alert mode
* Introduce alert mode operations in a separate patch and only then
  introduce the new alert mode
* Use 'skb->skb_iif' instead of 'skb->dev' because the latter is inside
  a union with 'dev_scratch' and therefore not guaranteed to point to a
  valid netdev
* Return '-EBUSY' instead of '-EOPNOTSUPP' when trying to configure drop
  monitor while it is monitoring
* Did not change schedule_work() in favor of schedule_work_on() as I did
  not observe a change in number of tail drops

[1] https://github.com/idosch/dropwatch/tree/packet-mode
[2] https://gist.github.com/idosch/3d524b887e16bc11b4b19e25c23dcc23#file-gistfile1-txt
[3] https://github.com/idosch/wireshark/tree/drop-monitor-v2
[4] https://gist.github.com/idosch/3d524b887e16bc11b4b19e25c23dcc23#file-gistfile2-txt
[5] https://github.com/the-tcpdump-group/libpcap/blob/master/pcap-netfilter-linux.c
[6] https://patchwork.ozlabs.org/cover/1143443/
[7] https://patchwork.ozlabs.org/cover/1135226/
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

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 <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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 <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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 <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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 <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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 <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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 <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Currently, the configure command does not do anything but return an
error. Subsequent patches will enable the command to change various
configuration options such as alert mode and packet truncation.

Similar to other netlink-based configuration channels, make sure only
users with the CAP_NET_ADMIN capability set can execute this command.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The function reset_per_cpu_data() allocates and prepares a new skb for
the summary netlink alert message ('NET_DM_CMD_ALERT'). The new skb is
stored in the per-CPU 'data' variable and the old is returned.

The function is invoked during module initialization and from the
workqueue, before an alert is sent. This means that it is possible to
receive an alert with stale data, if we stopped tracing when the
hysteresis timer ('data->send_timer') was pending.

Instead of invoking the function during module initialization, invoke it
just before we start tracing and ensure we get a fresh skb.

This also allows us to remove the calls to initialize the timer and the
work item from the module initialization path, since both could have
been triggered by the error paths of reset_per_cpu_data().
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The timer and work item are currently initialized once during module
init, but subsequent patches will need to associate different functions
with the work item, based on the configured alert mode.

Allow subsequent patches to make that change by initializing and
de-initializing these objects during tracing enable and disable.

This also guarantees that once the request to disable tracing returns,
no more netlink notifications will be generated.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>