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  • Christian Dietrich Christian Dietrich ccd5802
  • Niklas Gollenstede cyb8053
  • Niklas Gollenstede Niklas Gollenstede cng8984
  • Yannick Loeck Yannick Loeck cyl4616
4 authors
  1. Oct 20, 2013
    • Hannes Frederic Sowa's avatar
      net: introduce new macro net_get_random_once · a48e4292
      Hannes Frederic Sowa authored 
      
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 <mingo@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Eric Dumazet <edumazet@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      a48e4292
  3. Jun 05, 2013
  5. Mar 27, 2013
  7. Oct 12, 2012
  9. Aug 30, 2012
  11. Apr 12, 2012
  13. Mar 28, 2012
  15. May 27, 2011
  17. May 09, 2011
    • Alexey Dobriyan's avatar
      net: add mac_pton() for parsing MAC address · 4940fc88
      Alexey Dobriyan authored 
      
mac_pton() parses MAC address in form XX:XX:XX:XX:XX:XX and only in that form.

mac_pton() doesn't dirty result until it's sure string representation is valid.

mac_pton() doesn't care about characters _after_ last octet,
it's up to caller to deal with it.

mac_pton() diverges from 0/-E return value convention.
Target usage:

	if (!mac_pton(str, whatever->mac))
		return -EINVAL;
	/* ->mac being u8 [ETH_ALEN] is filled at this point. */
	/* optionally check str[3 * ETH_ALEN - 1] for termination */

Use mac_pton() in pktgen and netconsole for start.

Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      4940fc88
  19. Sep 23, 2010
  21. Sep 22, 2010
  23. Jul 12, 2010
  25. Sep 22, 2009
    • Ingo Molnar's avatar
      printk: Remove ratelimit.h from kernel.h · 3fff4c42
      Ingo Molnar authored 
      
Decouple kernel.h from ratelimit.h: the global declaration of
printk's ratelimit_state is not needed, and it leads to messy
circular dependencies due to ratelimit.h's (new) adding of a
spinlock_types.h include.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David S. Miller <davem@davemloft.net>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      3fff4c42
  27. Mar 26, 2009
  29. Jul 25, 2008
    • Dave Young's avatar
      printk ratelimiting rewrite · 717115e1
      Dave Young authored 
      
All ratelimit user use same jiffies and burst params, so some messages
(callbacks) will be lost.

For example:
a call printk_ratelimit(5 * HZ, 1)
b call printk_ratelimit(5 * HZ, 1) before the 5*HZ timeout of a, then b will
will be supressed.

- rewrite __ratelimit, and use a ratelimit_state as parameter.  Thanks for
  hints from andrew.

- Add WARN_ON_RATELIMIT, update rcupreempt.h

- remove __printk_ratelimit

- use __ratelimit in net_ratelimit

Signed-off-by: default avatarDave Young <hidave.darkstar@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      717115e1
  31. Jan 29, 2008
  33. Jan 28, 2008
  35. Aug 08, 2007
  37. May 31, 2007
    • Jerome Borsboom's avatar
      [NET]: parse ip:port strings correctly in in4_pton · 83f03fa5
      Jerome Borsboom authored 
      
in4_pton converts a textual representation of an ip4 address
into an integer representation. However, when the textual representation
is of in the form ip:port, e.g. 192.168.1.1:5060, and 'delim' is set to
-1, the function bails out with an error when reading the colon.

It makes sense to allow the colon as a delimiting character without
explicitly having to set it through the 'delim' variable as there can be
no ambiguity in the point where the ip address is completely parsed. This
function is indeed called from nf_conntrack_sip.c in this way to parse
textual ip:port combinations which fails due to the reason stated above.

Signed-off-by: default avatarJerome Borsboom <j.borsboom@erasmusmc.nl>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      83f03fa5
  39. Apr 26, 2007
  41. Feb 11, 2007
  43. Dec 03, 2006
  45. Oct 17, 2006
  47. Sep 29, 2006
  49. Sep 23, 2006
  51. Aug 18, 2006
  53. Apr 11, 2006
  55. Feb 05, 2006
  57. Jan 06, 2006
  59. Nov 13, 2005
  61. Aug 30, 2005
  63. Jul 28, 2005
  65. Apr 17, 2005
    • Linus Torvalds's avatar
      Linux-2.6.12-rc2 · 1da177e4
      Linus Torvalds authored 
      Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
      v2.6.12-rc2
      1da177e4