diff options
| -rw-r--r-- | include/linux/perf_event.h | 2 | ||||
| -rw-r--r-- | kernel/perf_event.c | 61 |
2 files changed, 36 insertions, 27 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 2a0da021c23f..441992a9775c 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -602,6 +602,8 @@ enum perf_event_active_state { struct file; +#define PERF_BUFFER_WRITABLE 0x01 + struct perf_buffer { atomic_t refcount; struct rcu_head rcu_head; diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 93d545801e43..f75c9c9c8177 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -2369,6 +2369,25 @@ unlock: rcu_read_unlock(); } +static unsigned long perf_data_size(struct perf_buffer *buffer); + +static void +perf_buffer_init(struct perf_buffer *buffer, long watermark, int flags) +{ + long max_size = perf_data_size(buffer); + + if (watermark) + buffer->watermark = min(max_size, watermark); + + if (!buffer->watermark) + buffer->watermark = max_size / 2; + + if (flags & PERF_BUFFER_WRITABLE) + buffer->writable = 1; + + atomic_set(&buffer->refcount, 1); +} + #ifndef CONFIG_PERF_USE_VMALLOC /* @@ -2401,7 +2420,7 @@ static void *perf_mmap_alloc_page(int cpu) } static struct perf_buffer * -perf_buffer_alloc(struct perf_event *event, int nr_pages) +perf_buffer_alloc(int nr_pages, long watermark, int cpu, int flags) { struct perf_buffer *buffer; unsigned long size; @@ -2414,18 +2433,20 @@ perf_buffer_alloc(struct perf_event *event, int nr_pages) if (!buffer) goto fail; - buffer->user_page = perf_mmap_alloc_page(event->cpu); + buffer->user_page = perf_mmap_alloc_page(cpu); if (!buffer->user_page) goto fail_user_page; for (i = 0; i < nr_pages; i++) { - buffer->data_pages[i] = perf_mmap_alloc_page(event->cpu); + buffer->data_pages[i] = perf_mmap_alloc_page(cpu); if (!buffer->data_pages[i]) goto fail_data_pages; } buffer->nr_pages = nr_pages; + perf_buffer_init(buffer, watermark, flags); + return buffer; fail_data_pages: @@ -2516,7 +2537,7 @@ static void perf_buffer_free(struct perf_buffer *buffer) } static struct perf_buffer * -perf_buffer_alloc(struct perf_event *event, int nr_pages) +perf_buffer_alloc(int nr_pages, long watermark, int cpu, int flags) { struct perf_buffer *buffer; unsigned long size; @@ -2540,6 +2561,8 @@ perf_buffer_alloc(struct perf_event *event, int nr_pages) buffer->page_order = ilog2(nr_pages); buffer->nr_pages = 1; + perf_buffer_init(buffer, watermark, flags); + return buffer; fail_all_buf: @@ -2591,23 +2614,6 @@ unlock: return ret; } -static void -perf_buffer_init(struct perf_event *event, struct perf_buffer *buffer) -{ - long max_size = perf_data_size(buffer); - - if (event->attr.watermark) { - buffer->watermark = min_t(long, max_size, - event->attr.wakeup_watermark); - } - - if (!buffer->watermark) - buffer->watermark = max_size / 2; - - atomic_set(&buffer->refcount, 1); - rcu_assign_pointer(event->buffer, buffer); -} - static void perf_buffer_free_rcu(struct rcu_head *rcu_head) { struct perf_buffer *buffer; @@ -2682,7 +2688,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) unsigned long vma_size; unsigned long nr_pages; long user_extra, extra; - int ret = 0; + int ret = 0, flags = 0; /* * Don't allow mmap() of inherited per-task counters. This would @@ -2747,15 +2753,16 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) WARN_ON(event->buffer); - buffer = perf_buffer_alloc(event, nr_pages); + if (vma->vm_flags & VM_WRITE) + flags |= PERF_BUFFER_WRITABLE; + + buffer = perf_buffer_alloc(nr_pages, event->attr.wakeup_watermark, + event->cpu, flags); if (!buffer) { ret = -ENOMEM; goto unlock; } - - perf_buffer_init(event, buffer); - if (vma->vm_flags & VM_WRITE) - event->buffer->writable = 1; + rcu_assign_pointer(event->buffer, buffer); atomic_long_add(user_extra, &user->locked_vm); event->mmap_locked = extra; |