Commit-ID: 74fcdae1a7fdf30de5413ccc1eca271415d01124
Gitweb: http://git.kernel.org/tip/74fcdae1a7fdf30de5413ccc1eca271415d01124
Author: Fenghua Yu <fenghua.yu@xxxxxxxxx>
AuthorDate: Thu, 1 Dec 2016 12:55:14 -0800
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Fri, 2 Dec 2016 01:13:02 +0100
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@xxxxxxxxx>
Cc: "Ravi V Shankar" <ravi.v.shankar@xxxxxxxxx>
Cc: "Tony Luck" <tony.luck@xxxxxxxxx>
Cc: "Marcelo Tosatti" <mtosatti@xxxxxxxxxx>
Cc: "Sai Prakhya" <sai.praneeth.prakhya@xxxxxxxxx>
Cc: "Vikas Shivappa" <vikas.shivappa@xxxxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <h.peter.anvin@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1480625714-54246-1-git-send-email-fenghua.yu@xxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/x86/include/asm/intel_rdt.h | 2 ++
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 2 ++
2 files changed, 4 insertions(+)
diff --git a/arch/x86/include/asm/intel_rdt.h b/arch/x86/include/asm/intel_rdt.h
index 6e90e87..95ce5c8 100644
--- a/arch/x86/include/asm/intel_rdt.h
+++ b/arch/x86/include/asm/intel_rdt.h
@@ -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)
{
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index fb8e03e..1afd3f3 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -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);
}
--
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