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

diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index 97c8d8321e044db900866eab0bb79058c8aad79c..b8dc141896b6ee036da70329295bcb9e2afc75cb 100644 (file)
--- 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 4040bf1a075cf3b37f31a024be1a7b476020a018..3e48693906031418223516aad9ca363f5f2585ef 100644 (file)
--- 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 d6bfdfd22abe87c5977fb41dc4928c045d55a804..8378785883dc2e03a638e4ed973cb7772aafe739 100644 (file)
--- a/arch/x86/kernel/cpu/intel_rdt_monitor.c
+++ b/arch/x86/kernel/cpu/intel_rdt_monitor.c
@@ -417,9 +417,9 @@ void mbm_handle_overflow(struct work_struct *work)
        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 86a69794d7e475dc58faf889204c7af883fe29f5..b529f93e8ed0990fc6c864dc2222646eaae9b51d 100644 (file)
--- 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;