Commit-ID: 74fcdae1a7fdf30de5413ccc1eca271415d01124 Gitweb: http://git.kernel.org/tip/74fcdae1a7fdf30de5413ccc1eca271415d01124 Author: Fenghua Yu <[email protected]> AuthorDate: Thu, 1 Dec 2016 12:55:14 -0800 Committer: Thomas Gleixner <[email protected]> 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 <[email protected]> Cc: "Ravi V Shankar" <[email protected]> Cc: "Tony Luck" <[email protected]> Cc: "Marcelo Tosatti" <[email protected]> Cc: "Sai Prakhya" <[email protected]> Cc: "Vikas Shivappa" <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Thomas Gleixner <[email protected]> --- 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); }
