target/linux/generic/patches-4.1/130-MIPS-kernel-fix-sched_getaffinity-with-MT-FPAFF-enab.patch

   1 From: Felix Fietkau <nbd@openwrt.org>
   2 Date: Sun, 19 Jul 2015 00:21:57 +0200
   3 Subject: [PATCH] MIPS: kernel: fix sched_getaffinity with MT FPAFF enabled
   4
   5 p->thread.user_cpus_allowed is zero-initialized and is only filled on
   6 the first sched_setaffinity call.
   7
   8 To avoid adding overhead in the task initialization codepath, simply OR
   9 the returned mask in sched_getaffinity with p->cpus_allowed.
  10
  11 Cc: stable@vger.kernel.org
  12 Signed-off-by: Felix Fietkau <nbd@openwrt.org>
  13 ---
  14
  15 --- a/arch/mips/kernel/mips-mt-fpaff.c
  16 +++ b/arch/mips/kernel/mips-mt-fpaff.c
  17 @@ -154,7 +154,7 @@ asmlinkage long mipsmt_sys_sched_getaffi
  18                                       unsigned long __user *user_mask_ptr)
  19  {
  20         unsigned int real_len;
  21 -       cpumask_t mask;
  22 +       cpumask_t allowed, mask;
  23         int retval;
  24         struct task_struct *p;
  25
  26 @@ -173,7 +173,8 @@ asmlinkage long mipsmt_sys_sched_getaffi
  27         if (retval)
  28                 goto out_unlock;
  29
  30 -       cpumask_and(&mask, &p->thread.user_cpus_allowed, cpu_possible_mask);
  31 +       cpumask_or(&allowed, &p->thread.user_cpus_allowed, &p->cpus_allowed);
  32 +       cpumask_and(&mask, &allowed, cpu_active_mask);
  33
  34  out_unlock:
  35         read_unlock(&tasklist_lock);