linux-kernel - [PATCH 3.4 058/107] MIPS: Fix sched_getaffinity with MT FPAFF enabled

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Date:	Wed, 16 Mar 2016 16:05:52 +0800
From:	lizf@...nel.org
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Felix Fietkau <nbd@...nwrt.org>,
	linux-mips@...ux-mips.org, Ralf Baechle <ralf@...ux-mips.org>,
	Zefan Li <lizefan@...wei.com>
Subject: [PATCH 3.4 058/107] MIPS: Fix sched_getaffinity with MT FPAFF enabled

From: Felix Fietkau <nbd@...nwrt.org>

3.4.111-rc1 review patch.  If anyone has any objections, please let me know.

------------------


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@...nwrt.org>
Cc: linux-mips@...ux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10740/
Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
Signed-off-by: Zefan Li <lizefan@...wei.com>
---
 arch/mips/kernel/mips-mt-fpaff.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/mips/kernel/mips-mt-fpaff.c b/arch/mips/kernel/mips-mt-fpaff.c
index 33f63ba..c7e2684 100644
--- 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);
-- 
1.9.1