kernel-regressions.patch

   1 rom ae060e0b7bc071bd73dd5319b93c3344d9e10212 Mon Sep 17 00:00:00 2001
   2 From: Manfred Spraul <manfred@colorfullife.com>
   3 To: torvalds@linux-foundation.org
   4 Cc: linux-kernel@vger.kernel.org
   5 Cc: cebbert@redhat.com
   6 Cc: airlied@gmail.com
   7 Cc: akpm@linux-foundation.org
   8 Bcc: manfred@colorfullife.com
   9 Date: Wed, 10 Dec 2008 18:17:06 +0100
  10 Subject: [PATCH] lib/idr.c: Fix bug introduced by RCU fix
  11
  12 The last patch to lib/idr.c caused a bug if idr_get_new_above() was
  13 called on an empty idr:
  14 Usually, nodes stay on the same layer. New layers are added to the top
  15 of the tree.
  16 The exception is idr_get_new_above() on an empty tree: In this case,
  17 the new root node is first added on layer 0, then moved upwards.
  18 p->layer was not updated.
  19
  20 As usual: You shall never rely on the source code comments, they
  21 will only mislead you.
  22
  23 Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
  24 ---
  25  lib/idr.c |    8 +++++++-
  26  1 files changed, 7 insertions(+), 1 deletions(-)
  27
  28 diff --git a/lib/idr.c b/lib/idr.c
  29 index 7a785a0..1c4f928 100644
  30 --- a/lib/idr.c
  31 +++ b/lib/idr.c
  32 @@ -220,8 +220,14 @@ build_up:
  33          */
  34         while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) {
  35                 layers++;
  36 -               if (!p->count)
  37 +               if (!p->count) {
  38 +                       /* special case: if the tree is currently empty,
  39 +                        * then we grow the tree by moving the top node
  40 +                        * upwards.
  41 +                        */
  42 +                       p->layer++;
  43                         continue;
  44 +               }
  45                 if (!(new = get_from_free_list(idp))) {
  46                         /*
  47                          * The allocation failed.  If we built part of
  48 --
  49 1.5.6.5
  50
  51 From: Trond Myklebust <Trond.Myklebust@netapp.com>
  52 Date: Thu, 20 Nov 2008 21:06:21 +0000 (-0500)
  53 Subject: SUNRPC: Fix a performance regression in the RPC authentication code
  54 X-Git-Tag: v2.6.28-rc6~4
  55 X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=23918b03060f6e572168fdde1798a905679d2e06
  56
  57 SUNRPC: Fix a performance regression in the RPC authentication code
  58
  59 Fix a regression reported by Max Kellermann whereby kernel profiling
  60 showed that his clients were spending 45% of their time in
  61 rpcauth_lookup_credcache.
  62
  63 It turns out that although his processes had identical uid/gid/groups,
  64 generic_match() was failing to detect this, because the task->group_info
  65 pointers were not shared. This again lead to the creation of a huge number
  66 of identical credentials at the RPC layer.
  67
  68 The regression is fixed by comparing the contents of task->group_info
  69 if the actual pointers are not identical.
  70
  71 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
  72 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  73 ---
  74
  75 diff --git a/net/sunrpc/auth_generic.c b/net/sunrpc/auth_generic.c
  76 index 744b79f..4028502 100644
  77 --- a/net/sunrpc/auth_generic.c
  78 +++ b/net/sunrpc/auth_generic.c
  79 @@ -133,13 +133,29 @@ static int
  80  generic_match(struct auth_cred *acred, struct rpc_cred *cred, int flags)
  81  {
  82         struct generic_cred *gcred = container_of(cred, struct generic_cred, gc_base);
  83 +       int i;
  84
  85         if (gcred->acred.uid != acred->uid ||
  86             gcred->acred.gid != acred->gid ||
  87 -           gcred->acred.group_info != acred->group_info ||
  88             gcred->acred.machine_cred != acred->machine_cred)
  89 -               return 0;
  90 +               goto out_nomatch;
  91 +
  92 +       /* Optimisation in the case where pointers are identical... */
  93 +       if (gcred->acred.group_info == acred->group_info)
  94 +               goto out_match;
  95 +
  96 +       /* Slow path... */
  97 +       if (gcred->acred.group_info->ngroups != acred->group_info->ngroups)
  98 +               goto out_nomatch;
  99 +       for (i = 0; i < gcred->acred.group_info->ngroups; i++) {
 100 +               if (GROUP_AT(gcred->acred.group_info, i) !=
 101 +                               GROUP_AT(acred->group_info, i))
 102 +                       goto out_nomatch;
 103 +       }
 104 +out_match:
 105         return 1;
 106 +out_nomatch:
 107 +       return 0;
 108  }
 109
 110  void __init rpc_init_generic_auth(void)