28 files changed, 164 insertions, 121 deletions

diff --git a/arch/powerpc/kernel/perf_event_fsl_emb.c b/arch/powerpc/kernel/perf_event_fsl_emb.c
index 4dcf5f831e9d..b0dc8f7069cd 100644
--- a/arch/powerpc/kernel/perf_event_fsl_emb.c
+++ b/arch/powerpc/kernel/perf_event_fsl_emb.c
@@ -596,6 +596,7 @@ static void record_and_restart(struct perf_event *event, unsigned long val,
                         if (left <= 0)
                                 left = period;
                         record = 1;
+                        event->hw.last_period = event->hw.sample_period;
                 }
                 if (left < 0x80000000LL)
                         val = 0x80000000LL - left;
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 84522c796987..126a302c481c 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2201,13 +2201,6 @@ find_lively_task_by_vpid(pid_t vpid)
         if (!task)
                 return ERR_PTR(-ESRCH);
 
-        /*
-         * Can't attach events to a dying task.
-         */
-        err = -ESRCH;
-        if (task->flags & PF_EXITING)
-                goto errout;
-
         /* Reuse ptrace permission checks for now. */
         err = -EACCES;
         if (!ptrace_may_access(task, PTRACE_MODE_READ))
@@ -2268,14 +2261,27 @@ retry:
 
                 get_ctx(ctx);
 
-                if (cmpxchg(&task->perf_event_ctxp[ctxn], NULL, ctx)) {
-                        /*
-                         * We raced with some other task; use
-                         * the context they set.
-                         */
+                err = 0;
+                mutex_lock(&task->perf_event_mutex);
+                /*
+                 * If it has already passed perf_event_exit_task().
+                 * we must see PF_EXITING, it takes this mutex too.
+                 */
+                if (task->flags & PF_EXITING)
+                        err = -ESRCH;
+                else if (task->perf_event_ctxp[ctxn])
+                        err = -EAGAIN;
+                else
+                        rcu_assign_pointer(task->perf_event_ctxp[ctxn], ctx);
+                mutex_unlock(&task->perf_event_mutex);
+
+                if (unlikely(err)) {
                         put_task_struct(task);
                         kfree(ctx);
-                        goto retry;
+
+                        if (err == -EAGAIN)
+                                goto retry;
+                        goto errout;
                 }
         }
 
@@ -5374,6 +5380,8 @@ free_dev:
         goto out;
 }
 
+static struct lock_class_key cpuctx_mutex;
+
 int perf_pmu_register(struct pmu *pmu, char *name, int type)
 {
         int cpu, ret;
@@ -5422,6 +5430,7 @@ skip_type:
 
                 cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
                 __perf_event_init_context(&cpuctx->ctx);
+                lockdep_set_class(&cpuctx->ctx.mutex, &cpuctx_mutex);
                 cpuctx->ctx.type = cpu_context;
                 cpuctx->ctx.pmu = pmu;
                 cpuctx->jiffies_interval = 1;
@@ -6127,7 +6136,7 @@ static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
          * scheduled, so we are now safe from rescheduling changing
          * our context.
          */
-        child_ctx = child->perf_event_ctxp[ctxn];
+        child_ctx = rcu_dereference_raw(child->perf_event_ctxp[ctxn]);
         task_ctx_sched_out(child_ctx, EVENT_ALL);
 
         /*
@@ -6440,11 +6449,6 @@ int perf_event_init_context(struct task_struct *child, int ctxn)
         unsigned long flags;
         int ret = 0;
 
-        child->perf_event_ctxp[ctxn] = NULL;
-
-        mutex_init(&child->perf_event_mutex);
-        INIT_LIST_HEAD(&child->perf_event_list);
-
         if (likely(!parent->perf_event_ctxp[ctxn]))
                 return 0;
 
@@ -6533,6 +6537,10 @@ int perf_event_init_task(struct task_struct *child)
 {
         int ctxn, ret;
 
+        memset(child->perf_event_ctxp, 0, sizeof(child->perf_event_ctxp));
+        mutex_init(&child->perf_event_mutex);
+        INIT_LIST_HEAD(&child->perf_event_list);
+
         for_each_task_context_nr(ctxn) {
                 ret = perf_event_init_context(child, ctxn);
                 if (ret)
diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 2b5387d53ba5..7141c42e1469 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -204,13 +204,11 @@ EXTRA_WARNINGS := $(EXTRA_WARNINGS) -Wshadow
 EXTRA_WARNINGS := $(EXTRA_WARNINGS) -Winit-self
 EXTRA_WARNINGS := $(EXTRA_WARNINGS) -Wpacked
 EXTRA_WARNINGS := $(EXTRA_WARNINGS) -Wredundant-decls
-EXTRA_WARNINGS := $(EXTRA_WARNINGS) -Wstack-protector
 EXTRA_WARNINGS := $(EXTRA_WARNINGS) -Wstrict-aliasing=3
 EXTRA_WARNINGS := $(EXTRA_WARNINGS) -Wswitch-default
 EXTRA_WARNINGS := $(EXTRA_WARNINGS) -Wswitch-enum
 EXTRA_WARNINGS := $(EXTRA_WARNINGS) -Wno-system-headers
 EXTRA_WARNINGS := $(EXTRA_WARNINGS) -Wundef
-EXTRA_WARNINGS := $(EXTRA_WARNINGS) -Wvolatile-register-var
 EXTRA_WARNINGS := $(EXTRA_WARNINGS) -Wwrite-strings
 EXTRA_WARNINGS := $(EXTRA_WARNINGS) -Wbad-function-cast
 EXTRA_WARNINGS := $(EXTRA_WARNINGS) -Wmissing-declarations
@@ -294,6 +292,13 @@ ifeq ($(call try-cc,$(SOURCE_HELLO),-Werror -fstack-protector-all),y)
         CFLAGS := $(CFLAGS) -fstack-protector-all
 endif
 
+ifeq ($(call try-cc,$(SOURCE_HELLO),-Werror -Wstack-protector),y)
+       CFLAGS := $(CFLAGS) -Wstack-protector
+endif
+
+ifeq ($(call try-cc,$(SOURC