linux-kernel - [tip:x86/cache] x86/intel_rdt/mbm: Fix MBM overflow handler during CPU hotplug

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Message-ID: <tip-bbc4615e0b7df5e21d0991adb4b2798508354924@git.kernel.org>
Date:   Wed, 16 Aug 2017 03:13:34 -0700
From:   tip-bot for Vikas Shivappa <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     vikas.shivappa@...ux.intel.com, tglx@...utronix.de,
        mingo@...nel.org, hpa@...or.com, linux-kernel@...r.kernel.org
Subject: [tip:x86/cache] x86/intel_rdt/mbm: Fix MBM overflow handler during
 CPU hotplug

Commit-ID:  bbc4615e0b7df5e21d0991adb4b2798508354924
Gitweb:     http://git.kernel.org/tip/bbc4615e0b7df5e21d0991adb4b2798508354924
Author:     Vikas Shivappa <vikas.shivappa@...ux.intel.com>
AuthorDate: Tue, 15 Aug 2017 18:00:42 -0700
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Wed, 16 Aug 2017 12:05:41 +0200

x86/intel_rdt/mbm: Fix MBM overflow handler during CPU hotplug

When a CPU is dying, the overflow worker is canceled and rescheduled on a
different CPU in the same domain. But if the timer is already about to
expire this essentially doubles the interval which might result in a non
detected overflow.

Cancel the overflow worker and reschedule it immediately on a different CPU
in same domain. The work could be flushed as well, but that would
reschedule it on the same CPU.

[ tglx: Rewrote changelog once again ]

Reported-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Vikas Shivappa <vikas.shivappa@...ux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: ravi.v.shankar@...el.com
Cc: tony.luck@...el.com
Cc: fenghua.yu@...el.com
Cc: peterz@...radead.org
Cc: eranian@...gle.com
Cc: vikas.shivappa@...el.com
Cc: ak@...ux.intel.com
Cc: davidcc@...gle.com
Link: http://lkml.kernel.org/r/1502845243-20454-2-git-send-email-vikas.shivappa@linux.intel.com

---
 arch/x86/kernel/cpu/intel_rdt.c          | 4 ++--
 arch/x86/kernel/cpu/intel_rdt.h          | 2 +-
 arch/x86/kernel/cpu/intel_rdt_monitor.c  | 4 ++--
 arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 2 +-
 4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index 97c8d83..b8dc141 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -447,7 +447,7 @@ static int domain_setup_mon_state(struct rdt_resource *r, struct rdt_domain *d)
 
 	if (is_mbm_enabled()) {
 		INIT_DELAYED_WORK(&d->mbm_over, mbm_handle_overflow);
-		mbm_setup_overflow_handler(d);
+		mbm_setup_overflow_handler(d, MBM_OVERFLOW_INTERVAL);
 	}
 
 	return 0;
@@ -540,7 +540,7 @@ static void domain_remove_cpu(int cpu, struct rdt_resource *r)
 	} else if (r == &rdt_resources_all[RDT_RESOURCE_L3] &&
 		   cpu == d->mbm_work_cpu && is_mbm_enabled()) {
 		cancel_delayed_work(&d->mbm_over);
-		mbm_setup_overflow_handler(d);
+		mbm_setup_overflow_handler(d, 0);
 	}
 }
 
diff --git a/arch/x86/kernel/cpu/intel_rdt.h b/arch/x86/kernel/cpu/intel_rdt.h
index 4040bf1..3e48693 100644
--- a/arch/x86/kernel/cpu/intel_rdt.h
+++ b/arch/x86/kernel/cpu/intel_rdt.h
@@ -422,7 +422,7 @@ void mkdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
 				    struct rdt_domain *d);
 void mon_event_read(struct rmid_read *rr, struct rdt_domain *d,
 		    struct rdtgroup *rdtgrp, int evtid, int first);
-void mbm_setup_overflow_handler(struct rdt_domain *dom);
+void mbm_setup_overflow_handler(struct rdt_domain *dom, unsigned long delay_ms);
 void mbm_handle_overflow(struct work_struct *work);
 
 #endif /* _ASM_X86_INTEL_RDT_H */
diff --git a/arch/x86/kernel/cpu/intel_rdt_monitor.c b/arch/x86/kernel/cpu/intel_rdt_monitor.c
index d6bfdfd..8378785 100644
--- a/arch/x86/kernel/cpu/intel_rdt_monitor.c
+++ b/arch/x86/kernel/cpu/intel_rdt_monitor.c
@@ -417,9 +417,9 @@ out_unlock:
 	mutex_unlock(&rdtgroup_mutex);
 }
 
-void mbm_setup_overflow_handler(struct rdt_domain *dom)
+void mbm_setup_overflow_handler(struct rdt_domain *dom, unsigned long delay_ms)
 {
-	unsigned long delay = msecs_to_jiffies(MBM_OVERFLOW_INTERVAL);
+	unsigned long delay = msecs_to_jiffies(delay_ms);
 	int cpu;
 
 	if (!static_branch_likely(&rdt_enable_key))
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index 86a6979..b529f93 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -1140,7 +1140,7 @@ static struct dentry *rdt_mount(struct file_system_type *fs_type,
 	if (is_mbm_enabled()) {
 		r = &rdt_resources_all[RDT_RESOURCE_L3];
 		list_for_each_entry(dom, &r->domains, list)
-			mbm_setup_overflow_handler(dom);
+			mbm_setup_overflow_handler(dom, MBM_OVERFLOW_INTERVAL);
 	}
 
 	goto out;