From: Davidlohr Bueso <dave@stgolabs.net>
Date: Mon, 31 Aug 2020 20:14:02 +0000 (-0700)
Subject: MIPS: Use rcu to lookup a task in mipsmt_sys_sched_setaffinity()
X-Git-Tag: microblaze-v5.11~106^2~73
X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=f0100c7f1aac7f10eb249c494de5016fcf8c0652;p=linux-2.6-microblaze.git

MIPS: Use rcu to lookup a task in mipsmt_sys_sched_setaffinity()

The call simply looks up the corresponding task (without iterating
the tasklist), which is safe under rcu instead of the tasklist_lock.
In addition, the setaffinity counter part already does this.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
---

diff --git a/arch/mips/kernel/mips-mt-fpaff.c b/arch/mips/kernel/mips-mt-fpaff.c
index 1a08428eedcf..6c590ef27648 100644
--- a/arch/mips/kernel/mips-mt-fpaff.c
+++ b/arch/mips/kernel/mips-mt-fpaff.c
@@ -167,7 +167,7 @@ asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len,
 		return -EINVAL;
 
 	get_online_cpus();
-	read_lock(&tasklist_lock);
+	rcu_read_lock();
 
 	retval = -ESRCH;
 	p = find_process_by_pid(pid);
@@ -181,7 +181,7 @@ asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len,
 	cpumask_and(&mask, &allowed, cpu_active_mask);
 
 out_unlock:
-	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 	put_online_cpus();
 	if (retval)
 		return retval;