Commit 74fcdae1 authored Dec 01, 2016 by Fenghua Yu Committed by Thomas Gleixner Dec 02, 2016

x86/intel_rdt: Call intel_rdt_sched_in() with preemption disabled



intel_rdt_sched_in() must be called with preemption disabled because the
function accesses percpu variables (pqr_state and closid).

If a task moves itself via move_myself() preemption is enabled, which
violates the calling convention and can result in incorrect closid
selection when the task gets preempted or migrated.

Add the required protection and a comment about the calling convention.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Cc: "Ravi V Shankar" <ravi.v.shankar@intel.com>
Cc: "Tony Luck" <tony.luck@intel.com>
Cc: "Marcelo Tosatti" <mtosatti@redhat.com>
Cc: "Sai Prakhya" <sai.praneeth.prakhya@intel.com>
Cc: "Vikas Shivappa" <vikas.shivappa@linux.intel.com>
Cc: "H. Peter Anvin" <h.peter.anvin@intel.com>
Link: http://lkml.kernel.org/r/1480625714-54246-1-git-send-email-fenghua.yu@intel.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

parent 0efc89be

arch/x86/include/asm/intel_rdt.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -192,6 +192,8 @@ int rdtgroup_schemata_show(struct kernfs_open_file *of,
		* resctrl file system.
		* - Caches the per cpu CLOSid values and does the MSR write only
		* when a task with a different CLOSid is scheduled in.
		*
		* Must be called with preemption disabled.
		*/
		static inline void intel_rdt_sched_in(void)
		{

arch/x86/kernel/cpu/intel_rdt_rdtgroup.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -326,8 +326,10 @@ static void move_myself(struct callback_head *head)
		kfree(rdtgrp);
		}

		preempt_disable();
		/* update PQR_ASSOC MSR to make resource group go into effect */
		intel_rdt_sched_in();
		preempt_enable();

		kfree(callback);
		}