linux-toradex.git/net/core/utils.c, branch v4.3-rc6

net: Add inet_proto_csum_replace_by_diff utility function

2015-08-18T04:33:06+00:00

This function updates a checksum field value and skb->csum based on
a value which is the difference between the old and new checksum.

Signed-off-by: Tom Herbert 
Signed-off-by: David S. Miller

net: Change pseudohdr argument of inet_proto_csum_replace* to be a bool

2015-08-18T04:33:06+00:00

inet_proto_csum_replace4,2,16 take a pseudohdr argument which indicates
the checksum field carries a pseudo header. This argument should be a
boolean instead of an int.

Signed-off-by: Tom Herbert 
Signed-off-by: David S. Miller

net: fix inet_proto_csum_replace4() sparse errors

2015-05-26T02:56:47+00:00

make C=2 CF=-D__CHECK_ENDIAN__ net/core/utils.o
...
net/core/utils.c:307:72: warning: incorrect type in argument 2 (different base types)
net/core/utils.c:307:72:    expected restricted __wsum [usertype] addend
net/core/utils.c:307:72:    got restricted __be32 [usertype] from
net/core/utils.c:308:34: warning: incorrect type in argument 2 (different base types)
net/core/utils.c:308:34:    expected restricted __wsum [usertype] addend
net/core/utils.c:308:34:    got restricted __be32 [usertype] to
net/core/utils.c:310:70: warning: incorrect type in argument 2 (different base types)
net/core/utils.c:310:70:    expected restricted __wsum [usertype] addend
net/core/utils.c:310:70:    got restricted __be32 [usertype] from
net/core/utils.c:310:77: warning: incorrect type in argument 2 (different base types)
net/core/utils.c:310:77:    expected restricted __wsum [usertype] addend
net/core/utils.c:310:77:    got restricted __be32 [usertype] to
net/core/utils.c:312:72: warning: incorrect type in argument 2 (different base types)
net/core/utils.c:312:72:    expected restricted __wsum [usertype] addend
net/core/utils.c:312:72:    got restricted __be32 [usertype] from
net/core/utils.c:313:35: warning: incorrect type in argument 2 (different base types)
net/core/utils.c:313:35:    expected restricted __wsum [usertype] addend
net/core/utils.c:313:35:    got restricted __be32 [usertype] to

Note we can use csum_replace4() helper

Fixes: 58e3cac5613aa ("net: optimise inet_proto_csum_replace4()")
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

net: Convert LIMIT_NETDEBUG to net_dbg_ratelimited

2014-11-11T19:10:31+00:00

Use the more common dynamic_debug capable net_dbg_ratelimited
and remove the LIMIT_NETDEBUG macro.

All messages are still ratelimited.

Some KERN_ uses are changed to KERN_DEBUG.

This may have some negative impact on messages that were
emitted at KERN_INFO that are not not enabled at all unless
DEBUG is defined or dynamic_debug is enabled.  Even so,
these messages are now _not_ emitted by default.

This also eliminates the use of the net_msg_warn sysctl
"/proc/sys/net/core/warnings".  For backward compatibility,
the sysctl is not removed, but it has no function.  The extern
declaration of net_msg_warn is removed from sock.h and made
static in net/core/sysctl_net_core.c

Miscellanea:

o Update the sysctl documentation
o Remove the embedded uses of pr_fmt
o Coalesce format fragments
o Realign arguments

Signed-off-by: Joe Perches 
Signed-off-by: David S. Miller

net: optimise inet_proto_csum_replace4()

2014-09-26T20:14:17+00:00

csum_partial() is a generic function which is not optimised for small fixed
length calculations, and its use requires to store "from" and "to" values in
memory while we already have them available in registers. This also has impact,
especially on RISC processors. In the same spirit as the change done by
Eric Dumazet on csum_replace2(), this patch rewrites inet_proto_csum_replace4()
taking into account RFC1624.

I spotted during a NATted tcp transfert that csum_partial() is one of top 5
consuming functions (around 8%), and the second user of csum_partial() is
inet_proto_csum_replace4().

Signed-off-by: Christophe Leroy 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller

net: avoid dependency of net_get_random_once on nop patching

2014-05-14T04:37:34+00:00

net_get_random_once depends on the static keys infrastructure to patch up
the branch to the slow path during boot. This was realized by abusing the
static keys api and defining a new initializer to not enable the call
site while still indicating that the branch point should get patched
up. This was needed to have the fast path considered likely by gcc.

The static key initialization during boot up normally walks through all
the registered keys and either patches in ideal nops or enables the jump
site but omitted that step on x86 if ideal nops where already placed at
static_key branch points. Thus net_get_random_once branches not always
became active.

This patch switches net_get_random_once to the ordinary static_key
api and thus places the kernel fast path in the - by gcc considered -
unlikely path.  Microbenchmarks on Intel and AMD x86-64 showed that
the unlikely path actually beats the likely path in terms of cycle cost
and that different nop patterns did not make much difference, thus this
switch should not be noticeable.

Fixes: a48e42920ff38b ("net: introduce new macro net_get_random_once")
Reported-by: Tuomas Räsänen 
Cc: Linus Torvalds 
Signed-off-by: Hannes Frederic Sowa 
Signed-off-by: David S. Miller

net: make net_get_random_once irq safe

2013-10-25T23:03:39+00:00

I initial build non irq safe version of net_get_random_once because I
would liked to have the freedom to defer even the extraction process of
get_random_bytes until the nonblocking pool is fully seeded.

I don't think this is a good idea anymore and thus this patch makes
net_get_random_once irq safe. Now someone using net_get_random_once does
not need to care from where it is called.

Cc: David S. Miller 
Cc: Eric Dumazet 
Signed-off-by: Hannes Frederic Sowa 
Signed-off-by: David S. Miller

net: introduce new macro net_get_random_once

2013-10-19T23:45:35+00:00

net_get_random_once is a new macro which handles the initialization
of secret keys. It is possible to call it in the fast path. Only the
initialization depends on the spinlock and is rather slow. Otherwise
it should get used just before the key is used to delay the entropy
extration as late as possible to get better randomness. It returns true
if the key got initialized.

The usage of static_keys for net_get_random_once is a bit uncommon so
it needs some further explanation why this actually works:

=== In the simple non-HAVE_JUMP_LABEL case we actually have ===
no constrains to use static_key_(true|false) on keys initialized with
STATIC_KEY_INIT_(FALSE|TRUE). So this path just expands in favor of
the likely case that the initialization is already done. The key is
initialized like this:

___done_key = { .enabled = ATOMIC_INIT(0) }

The check

                if (!static_key_true(&___done_key))                     \

expands into (pseudo code)

                if (!likely(___done_key > 0))

, so we take the fast path as soon as ___done_key is increased from the
helper function.

=== If HAVE_JUMP_LABELs are available this depends ===
on patching of jumps into the prepared NOPs, which is done in
jump_label_init at boot-up time (from start_kernel). It is forbidden
and dangerous to use net_get_random_once in functions which are called
before that!

At compilation time NOPs are generated at the call sites of
net_get_random_once. E.g. net/ipv6/inet6_hashtable.c:inet6_ehashfn (we
need to call net_get_random_once two times in inet6_ehashfn, so two NOPs):

      71:       0f 1f 44 00 00          nopl   0x0(%rax,%rax,1)
      76:       0f 1f 44 00 00          nopl   0x0(%rax,%rax,1)

Both will be patched to the actual jumps to the end of the function to
call __net_get_random_once at boot time as explained above.

arch_static_branch is optimized and inlined for false as return value and
actually also returns false in case the NOP is placed in the instruction
stream. So in the fast case we get a "return false". But because we
initialize ___done_key with (enabled != (entries & 1)) this call-site
will get patched up at boot thus returning true. The final check looks
like this:

                if (!static_key_true(&___done_key))                     \
                        ___ret = __net_get_random_once(buf,             \

expands to

                if (!!static_key_false(&___done_key))                     \
                        ___ret = __net_get_random_once(buf,             \

So we get true at boot time and as soon as static_key_slow_inc is called
on the key it will invert the logic and return false for the fast path.
static_key_slow_inc will change the branch because it got initialized
with .enabled == 0. After static_key_slow_inc is called on the key the
branch is replaced with a nop again.

=== Misc: ===
The helper defers the increment into a workqueue so we don't
have problems calling this code from atomic sections. A seperate boolean
(___done) guards the case where we enter net_get_random_once again before
the increment happend.

Cc: Ingo Molnar 
Cc: Steven Rostedt 
Cc: Jason Baron 
Cc: Peter Zijlstra 
Cc: Eric Dumazet 
Cc: "David S. Miller" 
Signed-off-by: Hannes Frederic Sowa 
Signed-off-by: David S. Miller

net: core: move mac_pton() to lib/net_utils.c

2013-06-05T19:00:27+00:00

Since we have at least one user of this function outside of CONFIG_NET
scope, we have to provide this function independently. The proposed
solution is to move it under lib/net_utils.c with corresponding
configuration variable and select wherever it is needed.

Signed-off-by: Andy Shevchenko 
Reported-by: Arnd Bergmann 
Acked-by: David S. Miller 
Acked-by: Arnd Bergmann 
Signed-off-by: Greg Kroah-Hartman

net: core: let's use native isxdigit instead of custom

2013-03-27T16:48:32+00:00

In kernel we have fast and pretty implementation of the isxdigit() function.
Let's use it.

Signed-off-by: Andy Shevchenko 
Signed-off-by: David S. Miller