1 files changed, 220 insertions, 136 deletions

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index bd7ce8ca5bb9..ff86c558af4c 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -283,14 +283,15 @@ ctx_group_list(struct perf_event *event, struct perf_event_context *ctx)
 static void
 list_add_event(struct perf_event *event, struct perf_event_context *ctx)
 {
-        struct perf_event *group_leader = event->group_leader;
+        WARN_ON_ONCE(event->attach_state & PERF_ATTACH_CONTEXT);
+        event->attach_state |= PERF_ATTACH_CONTEXT;
 
         /*
-         * Depending on whether it is a standalone or sibling event,
-         * add it straight to the context's event list, or to the group
-         * leader's sibling list:
+         * If we're a stand alone event or group leader, we go to the context
+         * list, group events are kept attached to the group so that
+         * perf_group_detach can, at all times, locate all siblings.
          */
-        if (group_leader == event) {
+        if (event->group_leader == event) {
                 struct list_head *list;
 
                 if (is_software_event(event))
@@ -298,13 +299,6 @@ list_add_event(struct perf_event *event, struct perf_event_context *ctx)
 
                 list = ctx_group_list(event, ctx);
                 list_add_tail(&event->group_entry, list);
-        } else {
-                if (group_leader->group_flags & PERF_GROUP_SOFTWARE &&
-                    !is_software_event(event))
-                        group_leader->group_flags &= ~PERF_GROUP_SOFTWARE;
-
-                list_add_tail(&event->group_entry, &group_leader->sibling_list);
-                group_leader->nr_siblings++;
         }
 
         list_add_rcu(&event->event_entry, &ctx->event_list);
@@ -313,6 +307,24 @@ list_add_event(struct perf_event *event, struct perf_event_context *ctx)
                 ctx->nr_stat++;
 }
 
+static void perf_group_attach(struct perf_event *event)
+{
+        struct perf_event *group_leader = event->group_leader;
+
+        WARN_ON_ONCE(event->attach_state & PERF_ATTACH_GROUP);
+        event->attach_state |= PERF_ATTACH_GROUP;
+
+        if (group_leader == event)
+                return;
+
+        if (group_leader->group_flags & PERF_GROUP_SOFTWARE &&
+                        !is_software_event(event))
+                group_leader->group_flags &= ~PERF_GROUP_SOFTWARE;
+
+        list_add_tail(&event->group_entry, &group_leader->sibling_list);
+        group_leader->nr_siblings++;
+}
+
 /*
  * Remove a event from the lists for its context.
  * Must be called with ctx->mutex and ctx->lock held.
@@ -320,17 +332,22 @@ list_add_event(struct perf_event *event, struct perf_event_context *ctx)
 static void
 list_del_event(struct perf_event *event, struct perf_event_context *ctx)
 {
-        if (list_empty(&event->group_entry))
+        /*
+         * We can have double detach due to exit/hot-unplug + close.
+         */
+        if (!(event->attach_state & PERF_ATTACH_CONTEXT))
                 return;
+
+        event->attach_state &= ~PERF_ATTACH_CONTEXT;
+
         ctx->nr_events--;
         if (event->attr.inherit_stat)
                 ctx->nr_stat--;
 
-        list_del_init(&event->group_entry);
         list_del_rcu(&event->event_entry);
 
-        if (event->group_leader != event)
-                event->group_leader->nr_siblings--;
+        if (event->group_leader == event)
+                list_del_init(&event->group_entry);
 
         update_group_times(event);
 
@@ -345,21 +362,39 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx)
                 event->state = PERF_EVENT_STATE_OFF;
 }
 
-static void
-perf_destroy_group(struct perf_event *event, struct perf_event_context *ctx)
+static void perf_group_detach(struct perf_event *event)
 {
         struct perf_event *sibling, *tmp;
+        struct list_head *list = NULL;
+
+        /*
+         * We can have double detach due to exit/hot-unplug + close.
+         */
+        if (!(event->attach_state & PERF_ATTACH_GROUP))
+                return;
+
+        event->attach_state &= ~PERF_ATTACH_GROUP;
+
+        /*
+         * If this is a sibling, remove it from its group.
+         */
+        if (event->group_leader != event) {
+                list_del_init(&event->group_entry);
+                event->group_leader->nr_siblings--;
+                return;
+        }
+
+        if (!list_empty(&event->group_entry))
+                list = &event->group_entry;
 
         /*
          * If this was a group event with sibling events then
          * upgrade the siblings to singleton events by adding them
-         * to the context list directly:
+         * to whatever list we are on.
          */
         list_for_each_entry_safe(sibling, tmp, &event->sibling_list, group_entry) {
-                struct list_head *list;
-
-                list = ctx_group_list(event, ctx);
-                list_move_tail(&sibling->group_entry, list);
+                if (list)
+                        list_move_tail(&sibling->group_entry, list);
                 sibling->group_leader = sibling;
 
                 /* Inherit group flags from the previous leader */
@@ -652,8 +687,11 @@ group_sched_in(struct perf_event *group_event,
         if (txn)
                 pmu->start_txn(pmu);
 
-        if (event_sched_in(group_event, cpuctx, ctx))
+        if (event_sched_in(group_event, cpuctx, ctx)) {
+                if (txn)
+                        pmu->cancel_txn(pmu);
                 return -EAGAIN;
+        }
 
         /*
          * Schedule in siblings as one group (if any):
@@ -675,9 +713,6 @@ group_sched_in(struct perf_event *group_event,
         }
 
 group_error:
-        if (txn)
-                pmu->cancel_txn(pmu);
-
         /*
          * Groups can be scheduled in as one unit only, so undo any
          * partial group before returning:
@@ -689,6 +724,9 @@ group_error:
         }
         event_sched_out(group_event, cpuctx, ctx);
 
+        if (txn)
+                pmu->cancel_txn(pmu);
+
         return -EAGAIN;
 }
 
@@ -727,6 +765,7 @@ static void add_event_to_ctx(struct perf_event *event,
                                struct perf_event_context *ctx)
 {
         list_add_event(event, ctx);
+        perf_group_attach(event);
         event->tstamp_enabled = ctx->time;
         event->tstamp_running = ctx->time;
         event->tstamp_stopped = ctx->time;
@@ -1468,6 +1507,9 @@ do {					\
                 divisor = nsec * frequency;
         }
 
+        if (!divisor)
+                return dividend;
+
         return div64_u64(dividend, divisor);
 }
 
@@ -1490,7 +1532,7 @@ static int perf_event_start(struct perf_event *event)
 static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count)
 {
         struct hw_perf_event *hwc = &event->hw;
-        u64 period, sample_period;
+        s64 period, sample_period;
         s64 delta;
 
         period = perf_calculate_period(event, nsec, count);
@@ -1841,6 +1883,7 @@ static void free_event_rcu(struct rcu_head *head)
 }
 
 static void perf_pending_sync(struct perf_event *event);
+static void perf_mmap_data_put(struct perf_mmap_data *data);
 
 static void free_event(struct perf_event *event)
 {
@@ -1856,9 +1899,9 @@ static void free_event(struct perf_event *event)
                         atomic_dec(&nr_task_events);
         }
 
-        if (event->output) {
-                fput(event->output->filp);
-                event->output = NULL;
+        if (event->data) {
+                perf_mmap_data_put(event->data);
+                event->data = NULL;
         }
 
         if (event->destroy)
@@ -1893,8 +1936,8 @@ int perf_event_release_kernel(struct perf_event *event)
          */
         mutex_lock_nested(&ctx->mutex, SINGLE_DEPTH_NESTING);
         raw_spin_lock_irq(&ctx->lock);
+        perf_group_detach(event);
         list_del_event(event, ctx);
-        perf_destroy_group(event, ctx);
         raw_spin_unlock_irq(&ctx->lock);
         mutex_unlock(&ctx->mutex);
 
@@ -2175,7 +2218,27 @@ unlock:
         return ret;
 }
 
-static int perf_event_set_output(struct perf_event *event, int output_fd);
+static const struct file_operations perf_fops;
+
+static struct perf_event *perf_fget_light(int fd, int *fput_needed)
+{
+        struct file *file;
+
+        file = fget_light(fd, fput_needed);
+        if (!file)
+                return ERR_PTR(-EBADF);
+
+        if (file->f_op != &perf_fops) {
+                fput_light(file, *fput_needed);
+                *fput_needed = 0;
+                return ERR_PTR(-EBADF);
+        }
+
+        return file->private_data;
+}
+
+static int perf_event_set_output(struct perf_event *event,
+                                 struct perf_event *output_event);
 static int perf_event_set_filter(struct perf_event *event, void __user *arg);
 
 static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
@@ -2202,7 +2265,23 @@ static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                 return perf_event_period(event, (u64 __user *)arg);
 
         case PERF_EVENT_IOC_SET_OUTPUT:
-                return perf_event_set_output(event, arg);
+        {
+                struct perf_event *output_event = NULL;
+                int fput_needed = 0;
+                int ret;
+
+                if (arg != -1) {
+                        output_event = perf_fget_light(arg, &fput_needed);
+                        if (IS_ERR(output_event))
+                                return PTR_ERR(output_event);
+                }
+
+                ret = perf_event_set_output(event, output_event);
+                if (output_event)
+                        fput_light(output_event->filp, fput_needed);
+
+                return ret;
+        }
 
         case PERF_EVENT_IOC_SET_FILTER:
                 return perf_event_set_filter(event, (void __user *)arg);
@@ -2335,8 +2414,6 @@ perf_mmap_data_alloc(struct perf_event *event, int nr_pages)
         unsigned long size;
         int i;
 
-        WARN_ON(atomic_read(&event->mmap_count));
-
         size = sizeof(struct perf_mmap_data);
         size += nr_pages * sizeof(void *);
 
@@ -2452,8 +2529,6 @@ perf_mmap_data_alloc(struct perf_event *event, int nr_pages)
         unsigned long size;
         void *all_buf;
 
-        WARN_ON(atomic_read(&event->mmap_count));
-
         size = sizeof(struct perf_mmap_data);
         size += sizeof(void *);
 
@@ -2536,7 +2611,7 @@ perf_mmap_data_init(struct perf_event *event, struct perf_mmap_data *data)
         if (!data->watermark)
                 data->watermark = max_size / 2;
 
-
+        atomic_set(&data->refcount, 1);
         rcu_assign_pointer(event->data, data);
 }
 
@@ -2548,13 +2623,26 @@ static void perf_mmap_data_free_rcu(struct rcu_head *rcu_head)
         perf_mmap_data_free(data);
 }
 
-static void perf_mmap_data_release(struct perf_event *event)
+static struct perf_mmap_data *perf_mmap_data_get(struct perf_event *event)
 {
-        struct perf_mmap_data *data = event->data;
+        struct perf_mmap_data *data;
+
+        rcu_read_lock();
+        data = rcu_dereference(event->data);
+        if (data) {
+                if (!atomic_inc_not_zero(&data->refcount))
+                        data = NULL;
+        }
+        rcu_read_unlock();
+
+        return data;
+}
 
-        WARN_ON(atomic_read(&event->mmap_count));
+static void perf_mmap_data_put(struct perf_mmap_data *data)
+{
+        if (!atomic_dec_and_test(&data->refcount))
+                return;
 
-        rcu_assign_pointer(event->data, NULL);
         call_rcu(&data->rcu_head, perf_mmap_data_free_rcu);
 }
 
@@ -2569,15 +2657,18 @@ static void perf_mmap_close(struct vm_area_struct *vma)
 {
         struct perf_event *event = vma->vm_file->private_data;
 
-        WARN_ON_ONCE(event->ctx->parent_ctx);
         if (atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex)) {
                 unsigned long size = perf_data_size(event->data);
-                struct user_struct *user = current_user();
+                struct user_struct *user = event->mmap_user;
+                struct perf_mmap_data *data = event->data;
 
                 atomic_long_sub((size >> PAGE_SHIFT) + 1, &user->locked_vm);
-                vma->vm_mm->locked_vm -= event->data->nr_locked;
-                perf_mmap_data_release(event);
+                vma->vm_mm->locked_vm -= event->mmap_locked;
+                rcu_assign_pointer(event->data, NULL);
                 mutex_unlock(&event->mmap_mutex);
+
+                perf_mmap_data_put(data);
+                free_uid(user);
         }
 }
 
@@ -2629,13 +2720,10 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 
         WARN_ON_ONCE(event->ctx->parent_ctx);
         mutex_lock(&event->mmap_mutex);
-        if (event->output) {
-                ret = -EINVAL;
-                goto unlock;
-        }
-
-        if (atomic_inc_not_zero(&event->mmap_count)) {
-                if (nr_pages != event->data->nr_pages)
+        if (event->data) {
+                if (event->data->nr_pages == nr_pages)
+                        atomic_inc(&event->data->refcount);
+                else
                         ret = -EINVAL;
                 goto unlock;
         }
@@ -2667,21 +2755,23 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
         WARN_ON(event->data);
 
         data = perf_mmap_data_alloc(event, nr_pages);
-        ret = -ENOMEM;
-        if (!data)
+        if (!data) {
+                ret = -ENOMEM;
                 goto unlock;
+        }
 
-        ret = 0;
         perf_mmap_data_init(event, data);
-
-        atomic_set(&event->mmap_count, 1);
-        atomic_long_add(user_extra, &user->locked_vm);
-        vma->vm_mm->locked_vm += extra;
-        event->data->nr_locked = extra;
         if (vma->vm_flags & VM_WRITE)
                 event->data->writable = 1;
 
+        atomic_long_add(user_extra, &user->locked_vm);
+        event->mmap_locked = extra;
+        event->mmap_user = get_current_user();
+        vma->vm_mm->locked_vm += event->mmap_locked;
+
 unlock:
+        if (!ret)
+                atomic_inc(&event->mmap_count);
         mutex_unlock(&event->mmap_mutex);
 
         vma->vm_flags |= VM_RESERVED;
@@ -2977,6 +3067,7 @@ __always_inline void perf_output_copy(struct perf_output_handle *handle,
 
                 len -= size;
                 handle->addr += size;
+                buf += size;
                 handle->size -= size;
                 if (!handle->size) {
                         struct perf_mmap_data *data = handle->data;
@@ -2993,7 +3084,6 @@ int perf_output_begin(struct perf_output_handle *handle,
                       struct perf_event *event, unsigned int size,
                       int nmi, int sample)
 {
-        struct perf_event *output_event;
         struct perf_mmap_data *data;
         unsigned long tail, offset, head;
         int have_lost;
@@ -3010,10 +3100,6 @@ int perf_output_begin(struct perf_output_handle *handle,
         if (event->parent)
                 event = event->parent;
 
-        output_event = rcu_dereference(event->output);
-        if (output_event)
-                event = output_event;
-
         data = rcu_dereference(event->data);
         if (!data)
                 goto out;
@@ -3972,13 +4058,6 @@ static void perf_swevent_overflow(struct perf_event *event, u64 overflow,
         }
 }
 
-static void perf_swevent_unthrottle(struct perf_event *event)
-{
-        /*
-         * Nothing to do, we already reset hwc->interrupts.
-         */
-}
-
 static void perf_swevent_add(struct perf_event *event, u64 nr,
                                int nmi, struct perf_sample_data *data,
                                struct pt_regs *regs)
@@ -4193,11 +4272,22 @@ static void perf_swevent_disable(struct perf_event *event)
         hlist_del_rcu(&event->hlist_entry);
 }
 
+static void perf_swevent_void(struct perf_event *event)
+{
+}
+
+static int perf_swevent_int(struct perf_event *event)
+{
+        return 0;
+}
+
 static const struct pmu perf_ops_generic = {
         .enable         = perf_swevent_enable,
         .disable        = perf_swevent_disable,
+        .start          = perf_swevent_int,
+        .stop           = perf_swevent_void,
         .read           = perf_swevent_read,
-        .unthrottle     = perf_swevent_unthrottle,
+        .unthrottle     = perf_swevent_void, /* hwc->interrupts already reset */
 };
 
 /*
@@ -4478,8 +4568,10 @@ static int swevent_hlist_get(struct perf_event *event)
 static const struct pmu perf_ops_tracepoint = {
         .enable         = perf_trace_enable,
         .disable        = perf_trace_disable,
+        .start          = perf_swevent_int,
+        .stop           = perf_swevent_void,
         .read           = perf_swevent_read,
-        .unthrottle     = perf_swevent_unthrottle,
+        .unthrottle     = perf_swevent_void,
 };
 
 static int perf_tp_filter_match(struct perf_event *event,
@@ -4912,39 +5004,17 @@ err_size:
         goto out;
 }
 
-static int perf_event_set_output(struct perf_event *event, int output_fd)
+static int
+perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
 {
-        struct perf_event *output_event = NULL;
-        struct file *output_file = NULL;
-        struct perf_event *old_output;
-        int fput_needed = 0;
+        struct perf_mmap_data *data = NULL, *old_data = NULL;
         int ret = -EINVAL;
 
-        /*
-         * Don't allow output of inherited per-task events. This would
-         * create performance issues due to cross cpu access.
-         */
-        if (event->cpu == -1 && event->attr.inherit)
-                return -EINVAL;
-
-        if (!output_fd)
+        if (!output_event)
                 goto set;
 
-        output_file = fget_light(output_fd, &fput_needed);
-        if (!output_file)
-                return -EBADF;
-
-        if (output_file->f_op != &perf_fops)
-                goto out;
-
-        output_event = output_file->private_data;
-
-        /* Don't chain output fds */
-        if (output_event->output)
-                goto out;
-
-        /* Don't set an output fd when we already have an output channel */
-        if (event->data)
+        /* don't allow circular references */
+        if (event == output_event)
                 goto out;
 
         /*
@@ -4959,26 +5029,28 @@ static int perf_event_set_output(struct perf_event *event, int output_fd)
         if (output_event->cpu == -1 && output_event->ctx != event->ctx)
                 goto out;
 
-        atomic_long_inc(&output_file->f_count);
-
 set:
         mutex_lock(&event->mmap_mutex);
-        old_output = event->output;
-        rcu_assign_pointer(event->output, output_event);
-        mutex_unlock(&event->mmap_mutex);
+        /* Can't redirect output if we've got an active mmap() */
+        if (atomic_read(&event->mmap_count))
+                goto unlock;
 
-        if (old_output) {
-                /*
-                 * we need to make sure no existing perf_output_*()
-                 * is still referencing this event.
-                 */
-                synchronize_rcu();
-                fput(old_output->filp);
+        if (output_event) {
+                /* get the buffer we want to redirect to */
+                data = perf_mmap_data_get(output_event);
+                if (!data)
+                        goto unlock;
         }
 
+        old_data = event->data;
+        rcu_assign_pointer(event->data, data);
         ret = 0;
+unlock:
+        mutex_unlock(&event->mmap_mutex);
+
+        if (old_data)
+                perf_mmap_data_put(old_data);
 out:
-        fput_light(output_file, fput_needed);
         return ret;
 }
 
@@ -4994,7 +5066,7 @@ SYSCALL_DEFINE5(perf_event_open,
                 struct perf_event_attr __user *, attr_uptr,
                 pid_t, pid, int, cpu, int, group_fd, unsigned long, flags)
 {
-        struct perf_event *event, *group_leader;
+        struct perf_event *event, *group_leader = NULL, *output_event = NULL;
         struct perf_event_attr attr;
         struct perf_event_context *ctx;
         struct file *event_file = NULL;
@@ -5034,19 +5106,25 @@ SYSCALL_DEFINE5(perf_event_open,
                 goto err_fd;
         }
 
+        if (group_fd != -1) {
+                group_leader = perf_fget_light(group_fd, &fput_needed);
+                if (IS_ERR(group_leader)) {
+                        err = PTR_ERR(group_leader);
+                        goto err_put_context;
+                }
+                group_file = group_leader->filp;
+                if (flags & PERF_FLAG_FD_OUTPUT)
+                        output_event = group_leader;
+                if (flags & PERF_FLAG_FD_NO_GROUP)
+                        group_leader = NULL;
+        }
+
         /*
          * Look up the group leader (we will attach this event to it):
          */
-        group_leader = NULL;
-        if (group_fd != -1 && !(flags & PERF_FLAG_FD_NO_GROUP)) {
+        if (group_leader) {
                 err = -EINVAL;
-                group_file = fget_light(group_fd, &fput_needed);
-                if (!group_file)
-                        goto err_put_context;
-                if (group_file->f_op != &perf_fops)
-                        goto err_put_context;
 
-                group_leader = group_file->private_data;
                 /*
                  * Do not allow a recursive hierarchy (this new sibling
                  * becoming part of another group-sibling):
@@ -5068,9 +5146,16 @@ SYSCALL_DEFINE5(perf_event_open,
 
         event = perf_event_alloc(&attr, cpu, ctx, group_leader,
                                      NULL, NULL, GFP_KERNEL);
-        err = PTR_ERR(event);
-        if (IS_ERR(event))
+        if (IS_ERR(event)) {
+                err = PTR_ERR(event);
                 goto err_put_context;
+        }
+
+        if (output_event) {
+                err = perf_event_set_output(event, output_event);
+                if (err)
+                        goto err_free_put_context;
+        }
 
         event_file = anon_inode_getfile("[perf_event]", &perf_fops, event, O_RDWR);
         if (IS_ERR(event_file)) {
@@ -5078,12 +5163,6 @@ SYSCALL_DEFINE5(perf_event_open,
                 goto err_free_put_context;
         }
 
-        if (flags & PERF_FLAG_FD_OUTPUT) {
-                err = perf_event_set_output(event, group_fd);
-                if (err)
-                        goto err_fput_free_put_context;
-        }
-
         event->filp = event_file;
         WARN_ON_ONCE(ctx->parent_ctx);
         mutex_lock(&ctx->mutex);
@@ -5097,12 +5176,16 @@ SYSCALL_DEFINE5(perf_event_open,
         list_add_tail(&event->owner_entry, &current->perf_event_list);
         mutex_unlock(&current->perf_event_mutex);
 
+        /*
+         * Drop the reference on the group_event after placing the
+         * new event on the sibling_list. This ensures destruction
+         * of the group leader will find the pointer to itself in
+         * perf_group_detach().
+         */
         fput_light(group_file, fput_needed);
         fd_install(event_fd, event_file);
         return event_fd;
 
-err_fput_free_put_context:
-        fput(event_file);
 err_free_put_context:
         free_event(event);
 err_put_context:
@@ -5420,6 +5503,7 @@ static void perf_free_event(struct perf_event *event,
 
         fput(parent->filp);
 
+        perf_group_detach(event);
         list_del_event(event, ctx);
         free_event(event);
 }