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x86/intel_rdt: Call intel_rdt_sched_in() with preemption disabled

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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>
This commit is contained in:
Fenghua Yu 2016-12-01 12:55:14 -08:00 committed by Thomas Gleixner
parent 0efc89be94
commit 74fcdae1a7
2 changed files with 4 additions and 0 deletions
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2
arch/x86/include/asm/intel_rdt.h
View File

@ -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)
{

2
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
View File

@ -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);
}