net: designate queue counts as "double ops protected" by instance lock

Drivers which opt into instance lock protection of ops should
only call set_real_num_*_queues() under the instance lock.
This m

net: designate queue counts as "double ops protected" by instance lock

Drivers which opt into instance lock protection of ops should
only call set_real_num_*_queues() under the instance lock.
This means that queue counts are double protected (writes
are under both rtnl_lock and instance lock, readers under
either).

Some readers may still be under the rtnl_lock, however, so for
now we need double protection of writers.

OTOH queue API paths are only under the protection of the instance
lock, so we need to validate that the instance is actually locking
ops, otherwise the input checks we do against queue count are racy.

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

show more ...

net: rfs: hash function change

RFS is using two kinds of hash tables.

First one is controlled by /proc/sys/net/core/rps_sock_flow_entries = 2^N
and using the N low order bits of the l4 hash is good

net: rfs: hash function change

RFS is using two kinds of hash tables.

First one is controlled by /proc/sys/net/core/rps_sock_flow_entries = 2^N
and using the N low order bits of the l4 hash is good enough.

Then each RX queue has its own hash table, controlled by
/sys/class/net/eth1/queues/rx-$q/rps_flow_cnt = 2^X

Current hash function, using the X low order bits is suboptimal,
because RSS is usually using Func(hash) = (hash % power_of_two);

For example, with 32 RX queues, 6 low order bits have no entropy
for a given queue.

Switch this hash function to hash_32(hash, log) to increase
chances to use all possible slots and reduce collisions.

Signed-off-by: Eric Dumazet <[email protected]>
Cc: Tom Herbert <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[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 sysfs operations

Most of them are already covered by the converted dev_xxx APIs.
Add the locking wrappers for the remaining ones.

Cc: Saeed Mahameed <saeed@ker

net: hold netdev instance lock during sysfs operations

Most of them are already covered by the converted dev_xxx APIs.
Add the locking wrappers for the remaining ones.

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 ...

net-sysfs: remove unused initial ret values

In some net-sysfs functions the ret value is initialized but never used
as it is always overridden. Remove those.

Signed-off-by: Antoine Tenart <atenart@

net-sysfs: remove unused initial ret values

In some net-sysfs functions the ret value is initialized but never used
as it is always overridden. Remove those.

Signed-off-by: Antoine Tenart <[email protected]>
Reviewed-by: Mateusz Polchlopek <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net-sysfs: restore behavior for not running devices

modprobe dummy dumdummies=1

Old behavior :

$ cat /sys/class/net/dummy0/carrier
cat: /sys/class/net/dummy0/carrier: Invalid argument

After blame

net-sysfs: restore behavior for not running devices

modprobe dummy dumdummies=1

Old behavior :

$ cat /sys/class/net/dummy0/carrier
cat: /sys/class/net/dummy0/carrier: Invalid argument

After blamed commit, an empty string is reported.

$ cat /sys/class/net/dummy0/carrier
$

In this commit, I restore the old behavior for carrier,
speed and duplex attributes.

Fixes: 79c61899b5ee ("net-sysfs: remove rtnl_trylock from device attributes")
Signed-off-by: Eric Dumazet <[email protected]>
Reported-by: Marco Leogrande <[email protected]>
Reviewed-by: Antoine Tenart <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net-sysfs: remove rtnl_trylock from queue attributes

Similar to the commit removing remove rtnl_trylock from device
attributes we here apply the same technique to networking queues.

Signed-off-by:

net-sysfs: remove rtnl_trylock from queue attributes

Similar to the commit removing remove rtnl_trylock from device
attributes we here apply the same technique to networking queues.

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

show more ...

net-sysfs: prevent uncleared queues from being re-added

With the (upcoming) removal of the rtnl_trylock/restart_syscall logic
and because of how Tx/Rx queues are implemented (and their
requirements)

net-sysfs: prevent uncleared queues from being re-added

With the (upcoming) removal of the rtnl_trylock/restart_syscall logic
and because of how Tx/Rx queues are implemented (and their
requirements), it might happen that a queue is re-added before having
the chance to be cleared. In such rare case, do not complete the queue
addition operation.

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

show more ...

net-sysfs: move queue attribute groups outside the default groups

Rx/tx queues embed their own kobject for registering their per-queue
sysfs files. The issue is they're using the kobject default gro

net-sysfs: move queue attribute groups outside the default groups

Rx/tx queues embed their own kobject for registering their per-queue
sysfs files. The issue is they're using the kobject default groups for
this and entirely rely on the kobject refcounting for releasing their
sysfs paths.

In order to remove rtnl_trylock calls we need sysfs files not to rely on
their associated kobject refcounting for their release. Thus we here
move queues sysfs files from the kobject default groups to their own
groups which can be removed separately.

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

show more ...

net-sysfs: remove rtnl_trylock from device attributes

There is an ABBA deadlock between net device unregistration and sysfs
files being accessed[1][2]. To prevent this from happening all paths
takin

net-sysfs: remove rtnl_trylock from device attributes

There is an ABBA deadlock between net device unregistration and sysfs
files being accessed[1][2]. To prevent this from happening all paths
taking the rtnl lock after the sysfs one (actually kn->active refcount)
use rtnl_trylock and return early (using restart_syscall)[3], which can
make syscalls to spin for a long time when there is contention on the
rtnl lock[4].

There are not many possibilities to improve the above:
- Rework the entire net/ locking logic.
- Invert two locks in one of the paths — not possible.

But here it's actually possible to drop one of the locks safely: the
kernfs_node refcount. More details in the code itself, which comes with
lots of comments.

Note that we check the device is alive in the added sysfs_rtnl_lock
helper to disallow sysfs operations to run after device dismantle has
started. This also help keeping the same behavior as before. Because of
this calls to dev_isalive in sysfs ops were removed.

[1] https://lore.kernel.org/netdev/[email protected]/
[2] https://lore.kernel.org/netdev/[email protected]/
[3] https://lore.kernel.org/netdev/20090226084924.16cb3e08@nehalam/
[4] https://lore.kernel.org/all/[email protected]/T/

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

show more ...

net: protect NAPI config fields with netdev_lock()

Protect the following members of netdev and napi by netdev_lock:
- defer_hard_irqs,
- gro_flush_timeout,
- irq_suspend_timeout.

The first two a

net: protect NAPI config fields with netdev_lock()

Protect the following members of netdev and napi by netdev_lock:
- defer_hard_irqs,
- gro_flush_timeout,
- irq_suspend_timeout.

The first two are written via sysfs (which this patch switches
to new lock), and netdev genl which holds both netdev and rtnl locks.

irq_suspend_timeout is only written by netdev genl.

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

show more ...

net: protect threaded status of NAPI with netdev_lock()

Now that NAPI instances can't come and go without holding
netdev->lock we can trivially switch from rtnl_lock() to
netdev_lock() for setting n

net: protect threaded status of NAPI with netdev_lock()

Now that NAPI instances can't come and go without holding
netdev->lock we can trivially switch from rtnl_lock() to
netdev_lock() for setting netdev->threaded via sysfs.

Note that since we do not lock netdev_lock around sysfs
calls in the core we don't have to "trylock" like we do
with rtnl_lock.

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

show more ...

net: napi: Make gro_flush_timeout per-NAPI

Allow per-NAPI gro_flush_timeout setting.

The existing sysfs parameter is respected; writes to sysfs will write to
all NAPI structs for the device and the

net: napi: Make gro_flush_timeout per-NAPI

Allow per-NAPI gro_flush_timeout setting.

The existing sysfs parameter is respected; writes to sysfs will write to
all NAPI structs for the device and the net_device gro_flush_timeout
field. Reads from sysfs will read from the net_device field.

The ability to set gro_flush_timeout on specific NAPI instances will be
added in a later commit, via netdev-genl.

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

show more ...

net: napi: Make napi_defer_hard_irqs per-NAPI

Add defer_hard_irqs to napi_struct in preparation for per-NAPI
settings.

The existing sysfs parameter is respected; writes to sysfs will write to
all N

net: napi: Make napi_defer_hard_irqs per-NAPI

Add defer_hard_irqs to napi_struct in preparation for per-NAPI
settings.

The existing sysfs parameter is respected; writes to sysfs will write to
all NAPI structs for the device and the net_device defer_hard_irq field.
Reads from sysfs show the net_device field.

The ability to set defer_hard_irqs on specific NAPI instances will be
added in a later commit, via netdev-genl.

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

show more ...

net: sysfs: Fix weird usage of class's namespace relevant fields

Device class has two namespace relevant fields which are associated by
the following usage:

struct class {
...
const struct kobj_n

net: sysfs: Fix weird usage of class's namespace relevant fields

Device class has two namespace relevant fields which are associated by
the following usage:

struct class {
...
const struct kobj_ns_type_operations *ns_type;
const void *(*namespace)(const struct device *dev);
...
}
if (dev->class && dev->class->ns_type)
dev->class->namespace(dev);

The usage looks weird since it checks @ns_type but calls namespace()
it is found for all existing class definitions that the other filed is
also assigned once one is assigned in current kernel tree, so fix this
weird usage by checking @namespace to call namespace().

Signed-off-by: Zijun Hu <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: napi: Prevent overflow of napi_defer_hard_irqs

In commit 6f8b12d661d0 ("net: napi: add hard irqs deferral feature")
napi_defer_irqs was added to net_device and napi_defer_irqs_count was
added t

net: napi: Prevent overflow of napi_defer_hard_irqs

In commit 6f8b12d661d0 ("net: napi: add hard irqs deferral feature")
napi_defer_irqs was added to net_device and napi_defer_irqs_count was
added to napi_struct, both as type int.

This value never goes below zero, so there is not reason for it to be a
signed int. Change the type for both from int to u32, and add an
overflow check to sysfs to limit the value to S32_MAX.

The limit of S32_MAX was chosen because the practical limit before this
patch was S32_MAX (anything larger was an overflow) and thus there are
no behavioral changes introduced. If the extra bit is needed in the
future, the limit can be raised.

Before this patch:

$ sudo bash -c 'echo 2147483649 > /sys/class/net/eth4/napi_defer_hard_irqs'
$ cat /sys/class/net/eth4/napi_defer_hard_irqs
-2147483647

After this patch:

$ sudo bash -c 'echo 2147483649 > /sys/class/net/eth4/napi_defer_hard_irqs'
bash: line 0: echo: write error: Numerical result out of range

Similarly, /sys/class/net/XXXXX/tx_queue_len is defined as unsigned:

include/linux/netdevice.h: unsigned int tx_queue_len;

And has an overflow check:

dev_change_tx_queue_len(..., unsigned long new_len):

if (new_len != (unsigned int)new_len)
return -ERANGE;

Suggested-by: Jakub Kicinski <[email protected]>
Signed-off-by: Joe Damato <[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: dqs: Do not use extern for unused dql_group

When CONFIG_DQL is not enabled, dql_group should be treated as a dead
declaration. However, its current extern declaration assumes the linker
will ig

net: dqs: Do not use extern for unused dql_group

When CONFIG_DQL is not enabled, dql_group should be treated as a dead
declaration. However, its current extern declaration assumes the linker
will ignore it, which is generally true across most compiler and
architecture combinations.

But in certain cases, the linker still attempts to resolve the extern
struct, even when the associated code is dead, resulting in a linking
error. For instance the following error in loongarch64:

>> loongarch64-linux-ld: net-sysfs.c:(.text+0x589c): undefined reference to `dql_group'

Modify the declaration of the dead object to be an empty declaration
instead of an extern. This change will prevent the linker from
attempting to resolve an undefined reference.

Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Fixes: 74293ea1c4db ("net: sysfs: Do not create sysfs for non BQL device")
Signed-off-by: Breno Leitao <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Tested-by: Simon Horman <[email protected]> # build-tested
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

netdev_features: convert NETIF_F_LLTX to dev->lltx

NETIF_F_LLTX can't be changed via Ethtool and is not a feature,
rather an attribute, very similar to IFF_NO_QUEUE (and hot).
Free one netdev_featur

netdev_features: convert NETIF_F_LLTX to dev->lltx

NETIF_F_LLTX can't be changed via Ethtool and is not a feature,
rather an attribute, very similar to IFF_NO_QUEUE (and hot).
Free one netdev_features_t bit and make it a "hot" private flag.

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

show more ...

ethtool: check device is present when getting link settings

A sysfs reader can race with a device reset or removal, attempting to
read device state when the device is not actually present. eg:

ethtool: check device is present when getting link settings

A sysfs reader can race with a device reset or removal, attempting to
read device state when the device is not actually present. eg:

[exception RIP: qed_get_current_link+17]
#8 [ffffb9e4f2907c48] qede_get_link_ksettings at ffffffffc07a994a [qede]
#9 [ffffb9e4f2907cd8] __rh_call_get_link_ksettings at ffffffff992b01a3
#10 [ffffb9e4f2907d38] __ethtool_get_link_ksettings at ffffffff992b04e4
#11 [ffffb9e4f2907d90] duplex_show at ffffffff99260300
#12 [ffffb9e4f2907e38] dev_attr_show at ffffffff9905a01c
#13 [ffffb9e4f2907e50] sysfs_kf_seq_show at ffffffff98e0145b
#14 [ffffb9e4f2907e68] seq_read at ffffffff98d902e3
#15 [ffffb9e4f2907ec8] vfs_read at ffffffff98d657d1
#16 [ffffb9e4f2907f00] ksys_read at ffffffff98d65c3f
#17 [ffffb9e4f2907f38] do_syscall_64 at ffffffff98a052fb

crash> struct net_device.state ffff9a9d21336000
state = 5,

state 5 is __LINK_STATE_START (0b1) and __LINK_STATE_NOCARRIER (0b100).
The device is not present, note lack of __LINK_STATE_PRESENT (0b10).

This is the same sort of panic as observed in commit 4224cfd7fb65
("net-sysfs: add check for netdevice being present to speed_show").

There are many other callers of __ethtool_get_link_ksettings() which
don't have a device presence check.

Move this check into ethtool to protect all callers.

Fixes: d519e17e2d01 ("net: export device speed and duplex via sysfs")
Fixes: 4224cfd7fb65 ("net-sysfs: add check for netdevice being present to speed_show")
Signed-off-by: Jamie Bainbridge <[email protected]>
Link: https://patch.msgid.link/8bae218864beaa44ed01628140475b9bf641c5b0.1724393671.git.jamie.bainbridge@gmail.com
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

netdevice: define and allocate &net_device _properly_

In fact, this structure contains a flexible array at the end, but
historically its size, alignment etc., is calculated manually.
There are sever

netdevice: define and allocate &net_device _properly_

In fact, this structure contains a flexible array at the end, but
historically its size, alignment etc., is calculated manually.
There are several instances of the structure embedded into other
structures, but also there's ongoing effort to remove them and we
could in the meantime declare &net_device properly.
Declare the array explicitly, use struct_size() and store the array
size inside the structure, so that __counted_by() can be applied.
Don't use PTR_ALIGN(), as SLUB itself tries its best to ensure the
allocated buffer is aligned to what the user expects.
Also, change its alignment from %NETDEV_ALIGN to the cacheline size
as per several suggestions on the netdev ML.

bloat-o-meter for vmlinux:

free_netdev 445 440 -5
netdev_freemem 24 - -24
alloc_netdev_mqs 1481 1450 -31

On x86_64 with several NICs of different vendors, I was never able to
get a &net_device pointer not aligned to the cacheline size after the
change.

Signed-off-by: Alexander Lobakin <[email protected]>
Signed-off-by: Breno Leitao <[email protected]>
Reviewed-by: Przemek Kitszel <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: no longer acquire RTNL in threaded_show()

dev->threaded can be read locklessly, if we add
corresponding READ_ONCE()/WRITE_ONCE() annotations.

Signed-off-by: Eric Dumazet <[email protected]>

net: no longer acquire RTNL in threaded_show()

dev->threaded can be read locklessly, if we add
corresponding READ_ONCE()/WRITE_ONCE() annotations.

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

show more ...

net: constify net_class

AFAICS all users of net_class take a const struct class * argument.
Therefore fully constify net_class.

Signed-off-by: Heiner Kallweit <[email protected]>
Acked-by: Steph

net: constify net_class

AFAICS all users of net_class take a const struct class * argument.
Therefore fully constify net_class.

Signed-off-by: Heiner Kallweit <[email protected]>
Acked-by: Stephen Hemminger <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: dqs: use sysfs_emit() in favor of sprintf()

Commit 6025b9135f7a ("net: dqs: add NIC stall detector based on BQL")
added three sysfs files.

Use the recommended sysfs_emit() helper.

Signed-off-

net: dqs: use sysfs_emit() in favor of sprintf()

Commit 6025b9135f7a ("net: dqs: add NIC stall detector based on BQL")
added three sysfs files.

Use the recommended sysfs_emit() helper.

Signed-off-by: Eric Dumazet <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Breno Leitao <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...