MIPS: Fix sched_getaffinity with MT FPAFF enabled

commit 1d62d737555e1378eb62a8bba26644f7d97139d2 upstream.

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.

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>
[bwh: Backported to 3.2: also convert from obsolete cpumask API]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/mips/kernel/mips-mt-fpaff.c b/arch/mips/kernel/mips-mt-fpaff.c
index 802e616..c7e2684 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;
 
-       cpus_and(mask, p->thread.user_cpus_allowed, cpu_possible_map);
+       cpumask_or(&allowed, &p->thread.user_cpus_allowed, &p->cpus_allowed);
+       cpumask_and(&mask, &allowed, cpu_active_mask);
 
 out_unlock:
        read_unlock(&tasklist_lock);