Merge branch 'perf/urgent' into perf/core, to resolve conflict and to prepare for new patches

Conflicts:
	arch/x86/kernel/traps.c

Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 80 insertions, 73 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index e9ef0c6646af..8fac2056d51e 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2973,6 +2973,22 @@ out:
         local_irq_restore(flags);
 }
 
+void perf_event_exec(void)
+{
+        struct perf_event_context *ctx;
+        int ctxn;
+
+        rcu_read_lock();
+        for_each_task_context_nr(ctxn) {
+                ctx = current->perf_event_ctxp[ctxn];
+                if (!ctx)
+                        continue;
+
+                perf_event_enable_on_exec(ctx);
+        }
+        rcu_read_unlock();
+}
+
 /*
  * Cross CPU call to read the hardware event
  */
@@ -3195,7 +3211,8 @@ static void free_event_rcu(struct rcu_head *head)
 }
 
 static void ring_buffer_put(struct ring_buffer *rb);
-static void ring_buffer_detach(struct perf_event *event, struct ring_buffer *rb);
+static void ring_buffer_attach(struct perf_event *event,
+                               struct ring_buffer *rb);
 
 static void unaccount_event_cpu(struct perf_event *event, int cpu)
 {
@@ -3259,8 +3276,6 @@ static void _free_event(struct perf_event *event)
         unaccount_event(event);
 
         if (event->rb) {
-                struct ring_buffer *rb;
-
                 /*
                  * Can happen when we close an event with re-directed output.
                  *
@@ -3268,12 +3283,7 @@ static void _free_event(struct perf_event *event)
                  * over us; possibly making our ring_buffer_put() the last.
                  */
                 mutex_lock(&event->mmap_mutex);
-                rb = event->rb;
-                if (rb) {
-                        rcu_assign_pointer(event->rb, NULL);
-                        ring_buffer_detach(event, rb);
-                        ring_buffer_put(rb); /* could be last */
-                }
+                ring_buffer_attach(event, NULL);
                 mutex_unlock(&event->mmap_mutex);
         }
 
@@ -3870,28 +3880,47 @@ unlock:
 static void ring_buffer_attach(struct perf_event *event,
                                struct ring_buffer *rb)
 {
+        struct ring_buffer *old_rb = NULL;
         unsigned long flags;
 
-        if (!list_empty(&event->rb_entry))
-                return;
+        if (event->rb) {
+                /*
+                 * Should be impossible, we set this when removing
+                 * event->rb_entry and wait/clear when adding event->rb_entry.
+                 */
+                WARN_ON_ONCE(event->rcu_pending);
 
-        spin_lock_irqsave(&rb->event_lock, flags);
-        if (list_empty(&event->rb_entry))
-                list_add(&event->rb_entry, &rb->event_list);
-        spin_unlock_irqrestore(&rb->event_lock, flags);
-}
+                old_rb = event->rb;
+                event->rcu_batches = get_state_synchronize_rcu();
+                event->rcu_pending = 1;
 
-static void ring_buffer_detach(struct perf_event *event, struct ring_buffer *rb)
-{
-        unsigned long flags;
+                spin_lock_irqsave(&old_rb->event_lock, flags);
+                list_del_rcu(&event->rb_entry);
+                spin_unlock_irqrestore(&old_rb->event_lock, flags);
+        }
 
-        if (list_empty(&event->rb_entry))
-                return;
+        if (event->rcu_pending && rb) {
+                cond_synchronize_rcu(event->rcu_batches);
+                event->rcu_pending = 0;
+        }
+
+        if (rb) {
+                spin_lock_irqsave(&rb->event_lock, flags);
+                list_add_rcu(&event->rb_entry, &rb->event_list);
+                spin_unlock_irqrestore(&rb->event_lock, flags);
+        }
+
+        rcu_assign_pointer(event->rb, rb);
 
-        spin_lock_irqsave(&rb->event_lock, flags);
-        list_del_init(&event->rb_entry);
-        wake_up_all(&event->waitq);
-        spin_unlock_irqrestore(&rb->event_lock, flags);
+        if (old_rb) {
+                ring_buffer_put(old_rb);
+                /*
+                 * Since we detached before setting the new rb, so that we
+                 * could attach the new rb, we could have missed a wakeup.
+                 * Provide it now.
+                 */
+                wake_up_all(&event->waitq);
+        }
 }
 
 static void ring_buffer_wakeup(struct perf_event *event)
@@ -3960,7 +3989,7 @@ static void perf_mmap_close(struct vm_area_struct *vma)
 {
         struct perf_event *event = vma->vm_file->private_data;
 
-        struct ring_buffer *rb = event->rb;
+        struct ring_buffer *rb = ring_buffer_get(event);
         struct user_struct *mmap_user = rb->mmap_user;
         int mmap_locked = rb->mmap_locked;
         unsigned long size = perf_data_size(rb);
@@ -3968,18 +3997,14 @@ static void perf_mmap_close(struct vm_area_struct *vma)
         atomic_dec(&rb->mmap_count);
 
         if (!atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex))
-                return;
+                goto out_put;
 
-        /* Detach current event from the buffer. */
-        rcu_assign_pointer(event->rb, NULL);
-        ring_buffer_detach(event, rb);
+        ring_buffer_attach(event, NULL);
         mutex_unlock(&event->mmap_mutex);
 
         /* If there's still other mmap()s of this buffer, we're done. */
-        if (atomic_read(&rb->mmap_count)) {
-                ring_buffer_put(rb); /* can't be last */
-                return;
-        }
+        if (atomic_read(&rb->mmap_count))
+                goto out_put;
 
         /*
          * No other mmap()s, detach from all other events that might redirect
@@ -4009,11 +4034,9 @@ again:
                  * still restart the iteration to make sure we're not now
                  * iterating the wrong list.
                  */
-                if (event->rb == rb) {
-                        rcu_assign_pointer(event->rb, NULL);
-                        ring_buffer_detach(event, rb);
-                        ring_buffer_put(rb); /* can't be last, we still have one */
-                }
+                if (event->rb == rb)
+                        ring_buffer_attach(event, NULL);
+
                 mutex_unlock(&event->mmap_mutex);
                 put_event(event);
 
@@ -4038,6 +4061,7 @@ again:
         vma->vm_mm->pinned_vm -= mmap_locked;
         free_uid(mmap_user);
 
+out_put:
         ring_buffer_put(rb); /* could be last */
 }
 
@@ -4155,7 +4179,6 @@ again:
         vma->vm_mm->pinned_vm += extra;
 
         ring_buffer_attach(event, rb);
-        rcu_assign_pointer(event->rb, rb);
 
         perf_event_init_userpage(event);
         perf_event_update_userpage(event);
@@ -5070,18 +5093,6 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event)
 void perf_event_comm(struct task_struct *task)
 {
         struct perf_comm_event comm_event;
-        struct perf_event_context *ctx;
-        int ctxn;
-
-        rcu_read_lock();
-        for_each_task_context_nr(ctxn) {
-                ctx = task->perf_event_ctxp[ctxn];
-                if (!ctx)
-                        continue;
-
-                perf_event_enable_on_exec(ctx);
-        }
-        rcu_read_unlock();
 
         if (!atomic_read(&nr_comm_events))
                 return;
@@ -5439,6 +5450,9 @@ struct swevent_htable {
 
         /* Recursion avoidance in each contexts */
         int                             recursion[PERF_NR_CONTEXTS];
+
+        /* Keeps track of cpu being initialized/exited */
+        bool                            online;
 };
 
 static DEFINE_PER_CPU(struct swevent_htable, swevent_htable);
@@ -5685,8 +5699,14 @@ static int perf_swevent_add(struct perf_event *event, int flags)
         hwc->state = !(flags & PERF_EF_START);
 
         head = find_swevent_head(swhash, event);
-        if (WARN_ON_ONCE(!head))
+        if (!head) {
+                /*
+                 * We can race with cpu hotplug code. Do not
+                 * WARN if the cpu just got unplugged.
+                 */
+                WARN_ON_ONCE(swhash->online);
                 return -EINVAL;
+        }
 
         hlist_add_head_rcu(&event->hlist_entry, head);
 
@@ -6956,7 +6976,7 @@ err_size:
 static int
 perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
 {
-        struct ring_buffer *rb = NULL, *old_rb = NULL;
+        struct ring_buffer *rb = NULL;
         int ret = -EINVAL;
 
         if (!output_event)
@@ -6984,8 +7004,6 @@ set:
         if (atomic_read(&event->mmap_count))
                 goto unlock;
 
-        old_rb = event->rb;
-
         if (output_event) {
                 /* get the rb we want to redirect to */
                 rb = ring_buffer_get(output_event);
@@ -6993,23 +7011,7 @@ set:
                         goto unlock;
         }
 
-        if (old_rb)
-                ring_buffer_detach(event, old_rb);
-
-        if (rb)
-                ring_buffer_attach(event, rb);
-
-        rcu_assign_pointer(event->rb, rb);
-
-        if (old_rb) {
-                ring_buffer_put(old_rb);
-                /*
-                 * Since we detached before setting the new rb, so that we
-                 * could attach the new rb, we could have missed a wakeup.
-                 * Provide it now.
-                 */
-                wake_up_all(&event->waitq);
-        }
+        ring_buffer_attach(event, rb);
 
         ret = 0;
 unlock:
@@ -7060,6 +7062,9 @@ SYSCALL_DEFINE5(perf_event_open,
         if (attr.freq) {
                 if (attr.sample_freq > sysctl_perf_event_sample_rate)
                         return -EINVAL;
+        } else {
+                if (attr.sample_period & (1ULL << 63))
+                        return -EINVAL;
         }
 
         /*
@@ -7872,6 +7877,7 @@ static void perf_event_init_cpu(int cpu)
         struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
 
         mutex_lock(&swhash->hlist_mutex);
+        swhash->online = true;
         if (swhash->hlist_refcount > 0) {
                 struct swevent_hlist *hlist;
 
@@ -7929,6 +7935,7 @@ static void perf_event_exit_cpu(int cpu)
         perf_event_exit_cpu_context(cpu);
 
         mutex_lock(&swhash->hlist_mutex);
+        swhash->online = false;
         swevent_hlist_release(swhash);
         mutex_unlock(&swhash->hlist_mutex);
 }