net: Remove RTNL dance for SIOCBRADDIF and SIOCBRDELIF.

SIOCBRDELIF is passed to dev_ioctl() first and later forwarded to
br_ioctl_call(), which causes unnecessary RTNL dance and the splat
below [0]

net: Remove RTNL dance for SIOCBRADDIF and SIOCBRDELIF.

SIOCBRDELIF is passed to dev_ioctl() first and later forwarded to
br_ioctl_call(), which causes unnecessary RTNL dance and the splat
below [0] under RTNL pressure.

Let's say Thread A is trying to detach a device from a bridge and
Thread B is trying to remove the bridge.

In dev_ioctl(), Thread A bumps the bridge device's refcnt by
netdev_hold() and releases RTNL because the following br_ioctl_call()
also re-acquires RTNL.

In the race window, Thread B could acquire RTNL and try to remove
the bridge device. Then, rtnl_unlock() by Thread B will release RTNL
and wait for netdev_put() by Thread A.

Thread A, however, must hold RTNL after the unlock in dev_ifsioc(),
which may take long under RTNL pressure, resulting in the splat by
Thread B.

Thread A (SIOCBRDELIF) Thread B (SIOCBRDELBR)
---------------------- ----------------------
sock_ioctl sock_ioctl
`- sock_do_ioctl `- br_ioctl_call
`- dev_ioctl `- br_ioctl_stub
|- rtnl_lock |
|- dev_ifsioc '
' |- dev = __dev_get_by_name(...)
|- netdev_hold(dev, ...) .
/ |- rtnl_unlock ------. |
| |- br_ioctl_call `---> |- rtnl_lock
Race | | `- br_ioctl_stub |- br_del_bridge
Window | | | |- dev = __dev_get_by_name(...)
| | | May take long | `- br_dev_delete(dev, ...)
| | | under RTNL pressure | `- unregister_netdevice_queue(dev, ...)
| | | | `- rtnl_unlock
\ | |- rtnl_lock <-' `- netdev_run_todo
| |- ... `- netdev_run_todo
| `- rtnl_unlock |- __rtnl_unlock
| |- netdev_wait_allrefs_any
|- netdev_put(dev, ...) <----------------'
Wait refcnt decrement
and log splat below

To avoid blocking SIOCBRDELBR unnecessarily, let's not call
dev_ioctl() for SIOCBRADDIF and SIOCBRDELIF.

In the dev_ioctl() path, we do the following:

1. Copy struct ifreq by get_user_ifreq in sock_do_ioctl()
2. Check CAP_NET_ADMIN in dev_ioctl()
3. Call dev_load() in dev_ioctl()
4. Fetch the master dev from ifr.ifr_name in dev_ifsioc()

3. can be done by request_module() in br_ioctl_call(), so we move
1., 2., and 4. to br_ioctl_stub().

Note that 2. is also checked later in add_del_if(), but it's better
performed before RTNL.

SIOCBRADDIF and SIOCBRDELIF have been processed in dev_ioctl() since
the pre-git era, and there seems to be no specific reason to process
them there.

[0]:
unregister_netdevice: waiting for wpan3 to become free. Usage count = 2
ref_tracker: wpan3@ffff8880662d8608 has 1/1 users at
__netdev_tracker_alloc include/linux/netdevice.h:4282 [inline]
netdev_hold include/linux/netdevice.h:4311 [inline]
dev_ifsioc+0xc6a/0x1160 net/core/dev_ioctl.c:624
dev_ioctl+0x255/0x10c0 net/core/dev_ioctl.c:826
sock_do_ioctl+0x1ca/0x260 net/socket.c:1213
sock_ioctl+0x23a/0x6c0 net/socket.c:1318
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl fs/ioctl.c:892 [inline]
__x64_sys_ioctl+0x1a4/0x210 fs/ioctl.c:892
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Fixes: 893b19587534 ("net: bridge: fix ioctl locking")
Reported-by: syzkaller <[email protected]>
Reported-by: yan kang <[email protected]>
Reported-by: yue sun <[email protected]>
Closes: https://lore.kernel.org/netdev/SY8P300MB0421225D54EB92762AE8F0F2A1D32@SY8P300MB0421.AUSP300.PROD.OUTLOOK.COM/
Signed-off-by: Kuniyuki Iwashima <[email protected]>
Acked-by: Stanislav Fomichev <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
Acked-by: Nikolay Aleksandrov <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>

show more ...

Revert "net: replace dev_addr_sem with netdev instance lock"

This reverts commit df43d8bf10316a7c3b1e47e3cc0057a54df4a5b8.

Cc: Kohei Enju <[email protected]>
Reviewed-by: Kuniyuki Iwashima <kuniyu@a

Revert "net: replace dev_addr_sem with netdev instance lock"

This reverts commit df43d8bf10316a7c3b1e47e3cc0057a54df4a5b8.

Cc: Kohei Enju <[email protected]>
Reviewed-by: Kuniyuki Iwashima <[email protected]>
Fixes: df43d8bf1031 ("net: replace dev_addr_sem with netdev instance lock")
Signed-off-by: Stanislav Fomichev <[email protected]>
Link: https://patch.msgid.link/[email protected]
Tested-by: Lei Yang <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

show more ...

net: move misc netdev_lock flavors to a separate header

Move the more esoteric helpers for netdev instance lock to
a dedicated header. This avoids growing netdevice.h to infinity
and makes rebuildin

net: move misc netdev_lock flavors to a separate header

Move the more esoteric helpers for netdev instance lock to
a dedicated header. This avoids growing netdevice.h to infinity
and makes rebuilding the kernel much faster (after touching
the header with the helpers).

The main netdev_lock() / netdev_unlock() functions are used
in static inlines in netdevice.h and will probably be used
most commonly, so keep them in netdevice.h.

Acked-by: Stanislav Fomichev <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: replace dev_addr_sem with netdev instance lock

Lockdep reports possible circular dependency in [0]. Instead of
fixing the ordering, replace global dev_addr_sem with netdev
instance lock. Most o

net: replace dev_addr_sem with netdev instance lock

Lockdep reports possible circular dependency in [0]. Instead of
fixing the ordering, replace global dev_addr_sem with netdev
instance lock. Most of the paths that set/get mac are RTNL
protected. Two places where it's not, convert to explicit
locking:
- sysfs address_show
- dev_get_mac_address via dev_ioctl

0: https://netdev-3.bots.linux.dev/vmksft-forwarding-dbg/results/993321/24-router-bridge-1d-lag-sh/stderr

Signed-off-by: Stanislav Fomichev <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: hold netdev instance lock during ioctl operations

Convert all ndo_eth_ioctl invocations to dev_eth_ioctl which does the
locking. Reflow some of the dev_siocxxx to drop else clause.

Cc: Saeed M

net: hold netdev instance lock during ioctl operations

Convert all ndo_eth_ioctl invocations to dev_eth_ioctl which does the
locking. Reflow some of the dev_siocxxx to drop else clause.

Cc: Saeed Mahameed <[email protected]>
Signed-off-by: Stanislav Fomichev <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

dev: Hold rtnl_net_lock() for dev_ifsioc().

Basically, dev_ifsioc() operates on the passed single netns (except
for netdev notifier chains with lower/upper devices for which we will
need more change

dev: Hold rtnl_net_lock() for dev_ifsioc().

Basically, dev_ifsioc() operates on the passed single netns (except
for netdev notifier chains with lower/upper devices for which we will
need more changes).

Let's hold rtnl_net_lock() for dev_ifsioc().

Now that NETDEV_CHANGENAME is always triggered under rtnl_net_lock()
of the device's netns. (do_setlink() and dev_ifsioc())

Signed-off-by: Kuniyuki Iwashima <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: Add the possibility to support a selected hwtstamp in netdevice

Introduce the description of a hwtstamp provider, mainly defined with a
the hwtstamp source and the phydev pointer.

Add a hwtsta

net: Add the possibility to support a selected hwtstamp in netdevice

Introduce the description of a hwtstamp provider, mainly defined with a
the hwtstamp source and the phydev pointer.

Add a hwtstamp provider description within the netdev structure to
allow saving the hwtstamp we want to use. This prepares for future
support of an ethtool netlink command to select the desired hwtstamp
provider. By default, the old API that does not support hwtstamp
selectability is used, meaning the hwtstamp provider pointer is unset.

Signed-off-by: Kory Maincent <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: Make net_hwtstamp_validate accessible

Make the net_hwtstamp_validate function accessible in prevision to use
it from ethtool to validate the hwtstamp configuration before setting it.

Reviewed-

net: Make net_hwtstamp_validate accessible

Make the net_hwtstamp_validate function accessible in prevision to use
it from ethtool to validate the hwtstamp configuration before setting it.

Reviewed-by: Florian Fainelli <[email protected]>
Reviewed-by: Jacob Keller <[email protected]>
Signed-off-by: Kory Maincent <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: Make dev_get_hwtstamp_phylib accessible

Make the dev_get_hwtstamp_phylib function accessible in prevision to use
it from ethtool to read the hwtstamp current configuration.

Reviewed-by: Floria

net: Make dev_get_hwtstamp_phylib accessible

Make the dev_get_hwtstamp_phylib function accessible in prevision to use
it from ethtool to read the hwtstamp current configuration.

Reviewed-by: Florian Fainelli <[email protected]>
Reviewed-by: Jacob Keller <[email protected]>
Signed-off-by: Kory Maincent <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

ipv4: Convert devinet_ioctl to per-netns RTNL.

ioctl(SIOCGIFCONF) calls dev_ifconf() that operates on the current netns.

Let's use per-netns RTNL helpers in dev_ifconf() and inet_gifconf().

Signed

ipv4: Convert devinet_ioctl to per-netns RTNL.

ioctl(SIOCGIFCONF) calls dev_ifconf() that operates on the current netns.

Let's use per-netns RTNL helpers in dev_ifconf() and inet_gifconf().

Signed-off-by: Kuniyuki Iwashima <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

show more ...

netdevice: convert private flags > BIT(31) to bitfields

Make dev->priv_flags `u32` back and define bits higher than 31 as
bitfield booleans as per Jakub's suggestion. This simplifies code
which acce

netdevice: convert private flags > BIT(31) to bitfields

Make dev->priv_flags `u32` back and define bits higher than 31 as
bitfield booleans as per Jakub's suggestion. This simplifies code
which accesses these bits with no optimization loss (testb both
before/after), allows to not extend &netdev_priv_flags each time,
but also scales better as bits > 63 in the future would only add
a new u64 to the structure with no complications, comparing to
that extending ::priv_flags would require converting it to a bitmap.
Note that I picked `unsigned long :1` to not lose any potential
optimizations comparing to `bool :1` etc.

Suggested-by: Jakub Kicinski <[email protected]>
Signed-off-by: Alexander Lobakin <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

show more ...

net: Change the API of PHY default timestamp to MAC

Change the API to select MAC default time stamping instead of the PHY.
Indeed the PHY is closer to the wire therefore theoretically it has less
de

net: Change the API of PHY default timestamp to MAC

Change the API to select MAC default time stamping instead of the PHY.
Indeed the PHY is closer to the wire therefore theoretically it has less
delay than the MAC timestamping but the reality is different. Due to lower
time stamping clock frequency, latency in the MDIO bus and no PHC hardware
synchronization between different PHY, the PHY PTP is often less precise
than the MAC. The exception is for PHY designed specially for PTP case but
these devices are not very widespread. For not breaking the compatibility
default_timestamp flag has been introduced in phy_device that is set by
the phy driver to know we are using the old API behavior.

Reviewed-by: Rahul Rameshbabu <[email protected]>
Signed-off-by: Kory Maincent <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: Move dev_set_hwtstamp_phylib to net/core/dev.h

This declaration was added to the header to be called from ethtool.
ethtool is separated from core for code organization but it is not really
a se

net: Move dev_set_hwtstamp_phylib to net/core/dev.h

This declaration was added to the header to be called from ethtool.
ethtool is separated from core for code organization but it is not really
a separate entity, it controls very core things.
As ethtool is an internal stuff it is not wise to have it in netdevice.h.
Move the declaration to net/core/dev.h instead.

Remove the EXPORT_SYMBOL_GPL call as ethtool can not be built as a module.

Reviewed-by: Willem de Bruijn <[email protected]>
Signed-off-by: Kory Maincent <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: partial revert of the "Make timestamping selectable: series

Revert following commits:

commit acec05fb78ab ("net_tstamp: Add TIMESTAMPING SOFTWARE and HARDWARE mask")
commit 11d55be06df0 ("net:

net: partial revert of the "Make timestamping selectable: series

Revert following commits:

commit acec05fb78ab ("net_tstamp: Add TIMESTAMPING SOFTWARE and HARDWARE mask")
commit 11d55be06df0 ("net: ethtool: Add a command to expose current time stamping layer")
commit bb8645b00ced ("netlink: specs: Introduce new netlink command to get current timestamp")
commit d905f9c75329 ("net: ethtool: Add a command to list available time stamping layers")
commit aed5004ee7a0 ("netlink: specs: Introduce new netlink command to list available time stamping layers")
commit 51bdf3165f01 ("net: Replace hwtstamp_source by timestamping layer")
commit 0f7f463d4821 ("net: Change the API of PHY default timestamp to MAC")
commit 091fab122869 ("net: ethtool: ts: Update GET_TS to reply the current selected timestamp")
commit 152c75e1d002 ("net: ethtool: ts: Let the active time stamping layer be selectable")
commit ee60ea6be0d3 ("netlink: specs: Introduce time stamping set command")

They need more time for reviews.

Link: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: Change the API of PHY default timestamp to MAC

Change the API to select MAC default time stamping instead of the PHY.
Indeed the PHY is closer to the wire therefore theoretically it has less
de

net: Change the API of PHY default timestamp to MAC

Change the API to select MAC default time stamping instead of the PHY.
Indeed the PHY is closer to the wire therefore theoretically it has less
delay than the MAC timestamping but the reality is different. Due to lower
time stamping clock frequency, latency in the MDIO bus and no PHC hardware
synchronization between different PHY, the PHY PTP is often less precise
than the MAC. The exception is for PHY designed specially for PTP case but
these devices are not very widespread. For not breaking the compatibility I
introduce a default_timestamp flag in phy_device that is set by the phy
driver to know we are using the old API behavior.

The phy_set_timestamp function is called at each call of phy_attach_direct.
In case of MAC driver using phylink this function is called when the
interface is turned up. Then if the interface goes down and up again the
last choice of timestamp will be overwritten by the default choice.
A solution could be to cache the timestamp status but it can bring other
issues. In case of SFP, if we change the module, it doesn't make sense to
blindly re-set the timestamp back to PHY, if the new module has a PHY with
mediocre timestamping capabilities.

Signed-off-by: Kory Maincent <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: Replace hwtstamp_source by timestamping layer

Replace hwtstamp_source which is only used by the kernel_hwtstamp_config
structure by the more widely use timestamp_layer structure. This is done
t

net: Replace hwtstamp_source by timestamping layer

Replace hwtstamp_source which is only used by the kernel_hwtstamp_config
structure by the more widely use timestamp_layer structure. This is done
to prepare the support of selectable timestamping source.

Signed-off-by: Kory Maincent <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: Make dev_set_hwtstamp_phylib accessible

Make the dev_set_hwtstamp_phylib function accessible in prevision to use
it from ethtool to reset the tstamp current configuration.

Reviewed-by: Florian

net: Make dev_set_hwtstamp_phylib accessible

Make the dev_set_hwtstamp_phylib function accessible in prevision to use
it from ethtool to reset the tstamp current configuration.

Reviewed-by: Florian Fainelli <[email protected]>
Signed-off-by: Kory Maincent <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: dsa: Use conduit and user terms

Use more inclusive terms throughout the DSA subsystem by moving away
from "master" which is replaced by "conduit" and "slave" which is
replaced by "user". No fun

net: dsa: Use conduit and user terms

Use more inclusive terms throughout the DSA subsystem by moving away
from "master" which is replaced by "conduit" and "slave" which is
replaced by "user". No functional changes.

Acked-by: Rob Herring <[email protected]>
Acked-by: Stephen Hemminger <[email protected]>
Reviewed-by: Vladimir Oltean <[email protected]>
Signed-off-by: Florian Fainelli <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: omit ndo_hwtstamp_get() call when possible in dev_set_hwtstamp_phylib()

Setting dev->priv_flags & IFF_SEE_ALL_HWTSTAMP_REQUESTS is only legal
for drivers which were converted to ndo_hwtstamp_ge

net: omit ndo_hwtstamp_get() call when possible in dev_set_hwtstamp_phylib()

Setting dev->priv_flags & IFF_SEE_ALL_HWTSTAMP_REQUESTS is only legal
for drivers which were converted to ndo_hwtstamp_get() and
ndo_hwtstamp_set(), and it is only there that we call ndo_hwtstamp_set()
for a request that otherwise goes to phylib (for stuff like packet traps,
which need to be undone if phylib failed, hence the old_cfg logic).

The problem is that we end up calling ndo_hwtstamp_get() when we don't
need to (even if the SIOCSHWTSTAMP wasn't intended for phylib, or if it
was, but the driver didn't set IFF_SEE_ALL_HWTSTAMP_REQUESTS). For those
unnecessary conditions, we share a code path with virtual drivers (vlan,
macvlan, bonding) where ndo_hwtstamp_get() is implemented as
generic_hwtstamp_get_lower(), and may be resolved through
generic_hwtstamp_ioctl_lower() if the lower device is unconverted.

I.e. this situation:

$ ip link add link eno0 name eno0.100 type vlan id 100
$ hwstamp_ctl -i eno0.100 -t 1

We are unprepared to deal with this, because if ndo_hwtstamp_get() is
resolved through a legacy ndo_eth_ioctl(SIOCGHWTSTAMP) lower_dev
implementation, that needs a non-NULL old_cfg.ifr pointer, and we don't
have it.

But we don't even need to deal with it either. In the general case,
drivers may not even implement SIOCGHWTSTAMP handling, only SIOCSHWTSTAMP,
so it makes sense to completely avoid a SIOCGHWTSTAMP call if we can.

The solution is to split the single "if" condition into 3 smaller ones,
thus separating the decision to call ndo_hwtstamp_get() from the
decision to call ndo_hwtstamp_set(). The third "if" condition is
identical to the first one, and both are subsets of the second one.
Thus, the "cfg" argument of kernel_hwtstamp_config_changed() is always
valid.

Reported-by: Eric Dumazet <[email protected]>
Closes: https://lore.kernel.org/netdev/CANn89iLOspJsvjPj+y8jikg7erXDomWe8sqHMdfL_2LQSFrPAg@mail.gmail.com/
Fixes: fd770e856e22 ("net: remove phy_has_hwtstamp() -> phy_mii_ioctl() decision from converted drivers")
Signed-off-by: Vladimir Oltean <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: remove phy_has_hwtstamp() -> phy_mii_ioctl() decision from converted drivers

It is desirable that the new .ndo_hwtstamp_set() API gives more
uniformity, less overhead and future flexibility w.r

net: remove phy_has_hwtstamp() -> phy_mii_ioctl() decision from converted drivers

It is desirable that the new .ndo_hwtstamp_set() API gives more
uniformity, less overhead and future flexibility w.r.t. the PHY
timestamping behavior.

Currently there are some drivers which allow PHY timestamping through
the procedure mentioned in Documentation/networking/timestamping.rst.
They don't do anything locally if phy_has_hwtstamp() is set, except for
lan966x which installs PTP packet traps.

Centralize that behavior in a new dev_set_hwtstamp_phylib() code
function, which calls either phy_mii_ioctl() for the phylib PHY,
or .ndo_hwtstamp_set() of the netdev, based on a single policy
(currently simplistic: phy_has_hwtstamp()).

Any driver converted to .ndo_hwtstamp_set() will automatically opt into
the centralized phylib timestamping policy. Unconverted drivers still
get to choose whether they let the PHY handle timestamping or not.

Netdev drivers with integrated PHY drivers that don't use phylib
presumably don't set dev->phydev, and those will always see
HWTSTAMP_SOURCE_NETDEV requests even when converted. The timestamping
policy will remain 100% up to them.

Signed-off-by: Vladimir Oltean <[email protected]>
Reviewed-by: Jacob Keller <[email protected]>
Tested-by: Horatiu Vultur <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: add hwtstamping helpers for stackable net devices

The stackable net devices with hwtstamping support (vlan, macvlan,
bonding) only pass the hwtstamping ops to the lower (real) device.

These dr

net: add hwtstamping helpers for stackable net devices

The stackable net devices with hwtstamping support (vlan, macvlan,
bonding) only pass the hwtstamping ops to the lower (real) device.

These drivers are the first that need to be converted to the new
timestamping API, because if they aren't prepared to handle that,
then no real device driver cannot be converted to the new API either.

After studying what vlan_dev_ioctl(), macvlan_eth_ioctl() and
bond_eth_ioctl() have in common, here we propose two generic
implementations of ndo_hwtstamp_get() and ndo_hwtstamp_set() which
can be called by those 3 drivers, with "dev" being their lower device.

These helpers cover both cases, when the lower driver is converted to
the new API or unconverted.

We need some hacks in case of an unconverted driver, namely to stuff
some pointers in struct kernel_hwtstamp_config which shouldn't have
been there (since the new API isn't supposed to need it). These will
be removed when all drivers will have been converted to the new API.

Signed-off-by: Maxim Georgiev <[email protected]>
Signed-off-by: Vladimir Oltean <[email protected]>
Reviewed-by: Jacob Keller <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: add NDOs for configuring hardware timestamping

Current hardware timestamping API for NICs requires implementing
.ndo_eth_ioctl() for SIOCGHWTSTAMP and SIOCSHWTSTAMP.

That API has some boilerpl

net: add NDOs for configuring hardware timestamping

Current hardware timestamping API for NICs requires implementing
.ndo_eth_ioctl() for SIOCGHWTSTAMP and SIOCSHWTSTAMP.

That API has some boilerplate such as request parameter translation
between user and kernel address spaces, handling possible translation
failures correctly, etc. Since it is the same all across the board, it
would be desirable to handle it through generic code.

Here we introduce .ndo_hwtstamp_get() and .ndo_hwtstamp_set(), which
implement that boilerplate and allow drivers to just act upon requests.

Suggested-by: Jakub Kicinski <[email protected]>
Signed-off-by: Maxim Georgiev <[email protected]>
Signed-off-by: Vladimir Oltean <[email protected]>
Reviewed-by: Jacob Keller <[email protected]>
Tested-by: Horatiu Vultur <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: dsa: replace NETDEV_PRE_CHANGE_HWTSTAMP notifier with a stub

There was a sort of rush surrounding commit 88c0a6b503b7 ("net: create a
netdev notifier for DSA to reject PTP on DSA master"), due

net: dsa: replace NETDEV_PRE_CHANGE_HWTSTAMP notifier with a stub

There was a sort of rush surrounding commit 88c0a6b503b7 ("net: create a
netdev notifier for DSA to reject PTP on DSA master"), due to a desire
to convert DSA's attempt to deny TX timestamping on a DSA master to
something that doesn't block the kernel-wide API conversion from
ndo_eth_ioctl() to ndo_hwtstamp_set().

What was required was a mechanism that did not depend on ndo_eth_ioctl(),
and what was provided was a mechanism that did not depend on
ndo_eth_ioctl(), while at the same time introducing something that
wasn't absolutely necessary - a new netdev notifier.

There have been objections from Jakub Kicinski that using notifiers in
general when they are not absolutely necessary creates complications to
the control flow and difficulties to maintainers who look at the code.
So there is a desire to not use notifiers.

In addition to that, the notifier chain gets called even if there is no
DSA in the system and no one is interested in applying any restriction.

Take the model of udp_tunnel_nic_ops and introduce a stub mechanism,
through which net/core/dev_ioctl.c can call into DSA even when
CONFIG_NET_DSA=m.

Compared to the code that existed prior to the notifier conversion, aka
what was added in commits:
- 4cfab3566710 ("net: dsa: Add wrappers for overloaded ndo_ops")
- 3369afba1e46 ("net: Call into DSA netdevice_ops wrappers")

this is different because we are not overloading any struct
net_device_ops of the DSA master anymore, but rather, we are exposing a
rather specific functionality which is orthogonal to which API is used
to enable it - ndo_eth_ioctl() or ndo_hwtstamp_set().

Also, what is similar is that both approaches use function pointers to
get from built-in code to DSA.

There is no point in replicating the function pointers towards
__dsa_master_hwtstamp_validate() once for every CPU port (dev->dsa_ptr).
Instead, it is sufficient to introduce a singleton struct dsa_stubs,
built into the kernel, which contains a single function pointer to
__dsa_master_hwtstamp_validate().

I find this approach preferable to what we had originally, because
dev->dsa_ptr->netdev_ops->ndo_do_ioctl() used to require going through
struct dsa_port (dev->dsa_ptr), and so, this was incompatible with any
attempts to add any data encapsulation and hide DSA data structures from
the outside world.

Link: https://lore.kernel.org/netdev/[email protected]/
Signed-off-by: Vladimir Oltean <[email protected]>
Reviewed-by: Florian Fainelli <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: create a netdev notifier for DSA to reject PTP on DSA master

The fact that PTP 2-step TX timestamping is broken on DSA switches if
the master also timestamps the same packets is documented by c

net: create a netdev notifier for DSA to reject PTP on DSA master

The fact that PTP 2-step TX timestamping is broken on DSA switches if
the master also timestamps the same packets is documented by commit
f685e609a301 ("net: dsa: Deny PTP on master if switch supports it").
We attempt to help the users avoid shooting themselves in the foot by
making DSA reject the timestamping ioctls on an interface that is a DSA
master, and the switch tree beneath it contains switches which are aware
of PTP.

The only problem is that there isn't an established way of intercepting
ndo_eth_ioctl calls, so DSA creates avoidable burden upon the network
stack by creating a struct dsa_netdevice_ops with overlaid function
pointers that are manually checked from the relevant call sites. There
used to be 2 such dsa_netdevice_ops, but now, ndo_eth_ioctl is the only
one left.

There is an ongoing effort to migrate driver-visible hardware timestamping
control from the ndo_eth_ioctl() based API to a new ndo_hwtstamp_set()
model, but DSA actively prevents that migration, since dsa_master_ioctl()
is currently coded to manually call the master's legacy ndo_eth_ioctl(),
and so, whenever a network device driver would be converted to the new
API, DSA's restrictions would be circumvented, because any device could
be used as a DSA master.

The established way for unrelated modules to react on a net device event
is via netdevice notifiers. So we create a new notifier which gets
called whenever there is an attempt to change hardware timestamping
settings on a device.

Finally, there is another reason why a netdev notifier will be a good
idea, besides strictly DSA, and this has to do with PHY timestamping.

With ndo_eth_ioctl(), all MAC drivers must manually call
phy_has_hwtstamp() before deciding whether to act upon SIOCSHWTSTAMP,
otherwise they must pass this ioctl to the PHY driver via
phy_mii_ioctl().

With the new ndo_hwtstamp_set() API, it will be desirable to simply not
make any calls into the MAC device driver when timestamping should be
performed at the PHY level.

But there exist drivers, such as the lan966x switch, which need to
install packet traps for PTP regardless of whether they are the layer
that provides the hardware timestamps, or the PHY is. That would be
impossible to support with the new API.

The proposal there, too, is to introduce a netdev notifier which acts as
a better cue for switching drivers to add or remove PTP packet traps,
than ndo_hwtstamp_set(). The one introduced here "almost" works there as
well, except for the fact that packet traps should only be installed if
the PHY driver succeeded to enable hardware timestamping, whereas here,
we need to deny hardware timestamping on the DSA master before it
actually gets enabled. This is why this notifier is called "PRE_", and
the notifier that would get used for PHY timestamping and packet traps
would be called NETDEV_CHANGE_HWTSTAMP. This isn't a new concept, for
example NETDEV_CHANGEUPPER and NETDEV_PRECHANGEUPPER do the same thing.

In expectation of future netlink UAPI, we also pass a non-NULL extack
pointer to the netdev notifier, and we make DSA populate it with an
informative reason for the rejection. To avoid making it go to waste, we
make the ioctl-based dev_set_hwtstamp() create a fake extack and print
the message to the kernel log.

Link: https://lore.kernel.org/netdev/20230401191215.tvveoi3lkawgg6g4@skbuf/
Link: https://lore.kernel.org/netdev/20230310164451.ls7bbs6pdzs4m6pw@skbuf/
Signed-off-by: Vladimir Oltean <[email protected]>
Reviewed-by: Florian Fainelli <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

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net: add struct kernel_hwtstamp_config and make net_hwtstamp_validate() use it

Jakub Kicinski suggested that we may want to add new UAPI for
controlling hardware timestamping through netlink in the

net: add struct kernel_hwtstamp_config and make net_hwtstamp_validate() use it

Jakub Kicinski suggested that we may want to add new UAPI for
controlling hardware timestamping through netlink in the future, and in
that case, we will be limited to the struct hwtstamp_config that is
currently passed in fixed binary format through the SIOCGHWTSTAMP and
SIOCSHWTSTAMP ioctls. It would be good if new kernel code already
started operating on an extensible kernel variant of that structure,
similar in concept to struct kernel_ethtool_coalesce vs struct
ethtool_coalesce.

Since struct hwtstamp_config is in include/uapi/linux/net_tstamp.h, here
we introduce include/linux/net_tstamp.h which shadows that other header,
but also includes it, so that existing includers of this header work as
before. In addition to that, we add the definition for the kernel-only
structure, and a helper which translates all fields by manual copying.
I am doing a manual copy in order to not force the alignment (or type)
of the fields of struct kernel_hwtstamp_config to be the same as of
struct hwtstamp_config, even though now, they are the same.

Link: https://lore.kernel.org/netdev/[email protected]/
Signed-off-by: Vladimir Oltean <[email protected]>
Reviewed-by: Florian Fainelli <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...