MIPS: 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>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10740/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/kernel/mips-mt-fpaff.c b/arch/mips/kernel/mips-mt-fpaff.c
index 3e4491a..789d7bf 100644 (file)
--- 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_getaffinity(pid_t pid, unsigned int len,
                                      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_getaffinity(pid_t pid, unsigned int len,
        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);