linux-toradex.git/net/wireless/wext-core.c, branch v5.8

wireless: wext: avoid gcc -O3 warning

2020-01-15T08:52:20+00:00

After the introduction of CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3,
the wext code produces a bogus warning:

In function 'iw_handler_get_iwstats',
    inlined from 'ioctl_standard_call' at net/wireless/wext-core.c:1015:9,
    inlined from 'wireless_process_ioctl' at net/wireless/wext-core.c:935:10,
    inlined from 'wext_ioctl_dispatch.part.8' at net/wireless/wext-core.c:986:8,
    inlined from 'wext_handle_ioctl':
net/wireless/wext-core.c:671:3: error: argument 1 null where non-null expected [-Werror=nonnull]
   memcpy(extra, stats, sizeof(struct iw_statistics));
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from arch/x86/include/asm/string.h:5,
net/wireless/wext-core.c: In function 'wext_handle_ioctl':
arch/x86/include/asm/string_64.h:14:14: note: in a call to function 'memcpy' declared here

The problem is that ioctl_standard_call() sometimes calls the handler
with a NULL argument that would cause a problem for iw_handler_get_iwstats.
However, iw_handler_get_iwstats never actually gets called that way.

Marking that function as noinline avoids the warning and leads
to slightly smaller object code as well.

Signed-off-by: Arnd Bergmann 
Link: https://lore.kernel.org/r/20200107200741.3588770-1-arnd@arndb.de
Signed-off-by: Johannes Berg

net: Don't take rtnl_lock() in wireless_nlevent_flush()

2018-03-29T17:47:53+00:00

This function iterates over net_namespace_list and flushes
the queue for every of them. What does this rtnl_lock()
protects?! Since we may add skbs to net::wext_nlevents
without rtnl_lock(), it does not protects us about queuers.

It guarantees, two threads can't flush the queue in parallel,
that can change the order, but since skb can be queued
in any order, it doesn't matter, how many threads do this
in parallel. In case of several threads, this will be even
faster.

So, we can remove rtnl_lock() here, as it was used for
iteration over net_namespace_list only.

Signed-off-by: Kirill Tkhai 
Signed-off-by: David S. Miller

net: Introduce net_rwsem to protect net_namespace_list

2018-03-29T17:47:53+00:00

rtnl_lock() is used everywhere, and contention is very high.
When someone wants to iterate over alive net namespaces,
he/she has no a possibility to do that without exclusive lock.
But the exclusive rtnl_lock() in such places is overkill,
and it just increases the contention. Yes, there is already
for_each_net_rcu() in kernel, but it requires rcu_read_lock(),
and this can't be sleepable. Also, sometimes it may be need
really prevent net_namespace_list growth, so for_each_net_rcu()
is not fit there.

This patch introduces new rw_semaphore, which will be used
instead of rtnl_mutex to protect net_namespace_list. It is
sleepable and allows not-exclusive iterations over net
namespaces list. It allows to stop using rtnl_lock()
in several places (what is made in next patches) and makes
less the time, we keep rtnl_mutex. Here we just add new lock,
while the explanation of we can remove rtnl_lock() there are
in next patches.

Fine grained locks generally are better, then one big lock,
so let's do that with net_namespace_list, while the situation
allows that.

Signed-off-by: Kirill Tkhai 
Signed-off-by: David S. Miller

net: Drop pernet_operations::async

2018-03-27T17:18:09+00:00

Synchronous pernet_operations are not allowed anymore.
All are asynchronous. So, drop the structure member.

Signed-off-by: Kirill Tkhai 
Signed-off-by: David S. Miller

net: Convert wext_pernet_ops

2018-02-13T15:36:08+00:00

These pernet_operations initialize and purge net::wext_nlevents
queue, and are not touched by foreign pernet_operations.

Mark them async.

Signed-off-by: Kirill Tkhai 
Acked-by: Andrei Vagin 
Signed-off-by: David S. Miller

lift handling of SIOCIW... out of dev_ioctl()

2018-01-25T00:13:45+00:00

Signed-off-by: Al Viro

dev_ioctl: copy only the smaller struct iwreq for wext

2017-06-14T11:52:44+00:00

Unfortunately, struct iwreq isn't a proper subset of struct ifreq,
but is still handled by the same code path. Robert reported that
then applications may (randomly) fault if the struct iwreq they
pass happens to land within 8 bytes of the end of a mapping (the
struct is only 32 bytes, vs. struct ifreq's 40 bytes).

To fix this, pull out the code handling wireless extension ioctls
and copy only the smaller structure in this case.

This bug goes back a long time, I tracked that it was introduced
into mainline in 2.1.15, over 20 years ago!

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=195869

Reported-by: Robert O'Callahan 
Signed-off-by: Johannes Berg

wireless: wext: use struct iwreq earlier in the call chain

2017-06-14T11:37:42+00:00

To make it clear that we never use struct ifreq, cast from it
directly in the wext entrypoint and use struct iwreq from there
on. The next patch will remove the cast again and pass the
correct struct from the beginning.

Signed-off-by: Johannes Berg

wireless: wext: remove ndo_do_ioctl fallback

2017-06-14T07:17:48+00:00

There are no longer any drivers (in the tree proper, I didn't
check all the staging drivers) that take WEXT ioctls through
this API, the only remaining ones that even have ndo_do_ioctl
are using it only for private ioctls.

Therefore, we can remove this call.

Signed-off-by: Johannes Berg

wext: uninline stream addition functions

2017-01-13T08:38:42+00:00

With 78, 111 and 85 bytes respectively (on x86-64), the
functions iwe_stream_add_event(), iwe_stream_add_point()
and iwe_stream_add_value() really shouldn't be inlines.

It appears that at least my compiler already decided
the same, and created a single instance of each one
of them for each file using it, but that's still a
number of instances in the system overall, which this
reduces.

Signed-off-by: Johannes Berg