x86-perf-uncore-deal-with-kfree.patch

Subject: x86: perf: Deal with kfree from atomic contexts
From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 04 Oct 2012 13:32:46 +0100

The x86 perf code allocates memory upfront because it might need
it. The detection that it is not needed happens in atomic context and
calls kfree from there. RT cant do that. Use kfree_rcu instead.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/kernel/cpu/perf_event.h              |    1 +
 arch/x86/kernel/cpu/perf_event_intel.c        |    2 +-
 arch/x86/kernel/cpu/perf_event_intel_uncore.c |    5 +++--
 arch/x86/kernel/cpu/perf_event_intel_uncore.h |    1 +
 4 files changed, 6 insertions(+), 3 deletions(-)

Index: linux-stable/arch/x86/kernel/cpu/perf_event.h
===================================================================
--- linux-stable.orig/arch/x86/kernel/cpu/perf_event.h
+++ linux-stable/arch/x86/kernel/cpu/perf_event.h
@@ -108,6 +108,7 @@ struct intel_shared_regs {
 	struct er_account       regs[EXTRA_REG_MAX];
 	int                     refcnt;		/* per-core: #HT threads */
 	unsigned                core_id;	/* per-core: core id */
+	struct rcu_head		rcu;
 };
 
 #define MAX_LBR_ENTRIES		16
Index: linux-stable/arch/x86/kernel/cpu/perf_event_intel.c
===================================================================
--- linux-stable.orig/arch/x86/kernel/cpu/perf_event_intel.c
+++ linux-stable/arch/x86/kernel/cpu/perf_event_intel.c
@@ -1707,7 +1707,7 @@ static void intel_pmu_cpu_dying(int cpu)
 	pc = cpuc->shared_regs;
 	if (pc) {
 		if (pc->core_id == -1 || --pc->refcnt == 0)
-			kfree(pc);
+			kfree_rcu(pc, rcu);
 		cpuc->shared_regs = NULL;
 	}
 
Index: linux-stable/arch/x86/kernel/cpu/perf_event_intel_uncore.c
===================================================================
--- linux-stable.orig/arch/x86/kernel/cpu/perf_event_intel_uncore.c
+++ linux-stable/arch/x86/kernel/cpu/perf_event_intel_uncore.c
@@ -2603,7 +2603,7 @@ static void __cpuinit uncore_cpu_dying(i
 			box = *per_cpu_ptr(pmu->box, cpu);
 			*per_cpu_ptr(pmu->box, cpu) = NULL;
 			if (box && atomic_dec_and_test(&box->refcnt))
-				kfree(box);
+				kfree_rcu(box, rcu);
 		}
 	}
 }
@@ -2633,7 +2633,8 @@ static int __cpuinit uncore_cpu_starting
 				if (exist && exist->phys_id == phys_id) {
 					atomic_inc(&exist->refcnt);
 					*per_cpu_ptr(pmu->box, cpu) = exist;
-					kfree(box);
+					if (box)
+						kfree_rcu(box, rcu);
 					box = NULL;
 					break;
 				}
Index: linux-stable/arch/x86/kernel/cpu/perf_event_intel_uncore.h
===================================================================
--- linux-stable.orig/arch/x86/kernel/cpu/perf_event_intel_uncore.h
+++ linux-stable/arch/x86/kernel/cpu/perf_event_intel_uncore.h
@@ -419,6 +419,7 @@ struct intel_uncore_box {
 	struct hrtimer hrtimer;
 	struct list_head list;
 	struct intel_uncore_extra_reg shared_regs[0];
+	struct rcu_head rcu;
 };
 
 #define UNCORE_BOX_FLAG_INITIATED	0