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freifunkist-firmware/target/linux/generic/patches-4.0/130-MIPS-kernel-fix-sched_g...

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From: Felix Fietkau <nbd@openwrt.org>
Date: Sun, 19 Jul 2015 00:21:57 +0200
Subject: [PATCH] MIPS: kernel: fix sched_getaffinity with MT FPAFF enabled
p->thread.user_cpus_allowed is zero-initialized and is only filled on
the first sched_setaffinity call.
To avoid adding overhead in the task initialization codepath, simply OR
the returned mask in sched_getaffinity with p->cpus_allowed.
Cc: stable@vger.kernel.org
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---
--- a/arch/mips/kernel/mips-mt-fpaff.c
+++ b/arch/mips/kernel/mips-mt-fpaff.c
@@ -154,7 +154,7 @@ asmlinkage long mipsmt_sys_sched_getaffi
unsigned long __user *user_mask_ptr)
{
unsigned int real_len;
- cpumask_t mask;
+ cpumask_t allowed, mask;
int retval;
struct task_struct *p;
@@ -173,7 +173,8 @@ asmlinkage long mipsmt_sys_sched_getaffi
if (retval)
goto out_unlock;
- cpumask_and(&mask, &p->thread.user_cpus_allowed, cpu_possible_mask);
+ cpumask_or(&allowed, &p->thread.user_cpus_allowed, &p->cpus_allowed);
+ cpumask_and(&mask, &allowed, cpu_active_mask);
out_unlock:
read_unlock(&tasklist_lock);