perf/bpf: Convert perf_event_array to use struct file

Robustify refcounting.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160126045947.GA40151@ast-mbp.thefacebook.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 6612732d8fd050f00e481e6e200b77dec1ad2527..4f90434b8d64f59145f647bc844eb28b73856029 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -729,7 +729,7 @@ extern int perf_event_init_task(struct task_struct *child);
 extern void perf_event_exit_task(struct task_struct *child);
 extern void perf_event_free_task(struct task_struct *task);
 extern void perf_event_delayed_put(struct task_struct *task);
-extern struct perf_event *perf_event_get(unsigned int fd);
+extern struct file *perf_event_get(unsigned int fd);
 extern const struct perf_event_attr *perf_event_attrs(struct perf_event *event);
 extern void perf_event_print_debug(void);
 extern void perf_pmu_disable(struct pmu *pmu);
@@ -1070,7 +1070,7 @@ static inline int perf_event_init_task(struct task_struct *child) { return 0; }
 static inline void perf_event_exit_task(struct task_struct *child)     { }
 static inline void perf_event_free_task(struct task_struct *task)      { }
 static inline void perf_event_delayed_put(struct task_struct *task)    { }
-static inline struct perf_event *perf_event_get(unsigned int fd)       { return ERR_PTR(-EINVAL); }
+static inline struct file *perf_event_get(unsigned int fd)     { return ERR_PTR(-EINVAL); }
 static inline const struct perf_event_attr *perf_event_attrs(struct perf_event *event)
 {
        return ERR_PTR(-EINVAL);

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index b0799bced518691bd847a16973be74184bcdcbaf..89ebbc4d1164fea26bdcb62561bd15838be6a2db 100644 (file)
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -291,10 +291,13 @@ static void *perf_event_fd_array_get_ptr(struct bpf_map *map, int fd)
 {
        struct perf_event *event;
        const struct perf_event_attr *attr;
+       struct file *file;
 
-       event = perf_event_get(fd);
-       if (IS_ERR(event))
-               return event;
+       file = perf_event_get(fd);
+       if (IS_ERR(file))
+               return file;
+
+       event = file->private_data;
 
        attr = perf_event_attrs(event);
        if (IS_ERR(attr))
@@ -304,24 +307,22 @@ static void *perf_event_fd_array_get_ptr(struct bpf_map *map, int fd)
                goto err;
 
        if (attr->type == PERF_TYPE_RAW)
-               return event;
+               return file;
 
        if (attr->type == PERF_TYPE_HARDWARE)
-               return event;
+               return file;
 
        if (attr->type == PERF_TYPE_SOFTWARE &&
            attr->config == PERF_COUNT_SW_BPF_OUTPUT)
-               return event;
+               return file;
 err:
-       perf_event_release_kernel(event);
+       fput(file);
        return ERR_PTR(-EINVAL);
 }
 
 static void perf_event_fd_array_put_ptr(void *ptr)
 {
-       struct perf_event *event = ptr;
-
-       perf_event_release_kernel(event);
+       fput((struct file *)ptr);
 }
 
 static const struct bpf_map_ops perf_event_array_ops = {

diff --git a/kernel/events/core.c b/kernel/events/core.c
index fe97f95f204ecd81d564eaf36f28d527f334befb..eb44730afea520f2b8cf056bc0529097c2182e1d 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8916,21 +8916,20 @@ void perf_event_delayed_put(struct task_struct *task)
                WARN_ON_ONCE(task->perf_event_ctxp[ctxn]);
 }
 
-struct perf_event *perf_event_get(unsigned int fd)
+struct file *perf_event_get(unsigned int fd)
 {
-       int err;
-       struct fd f;
-       struct perf_event *event;
+       struct file *file;
 
-       err = perf_fget_light(fd, &f);
-       if (err)
-               return ERR_PTR(err);
+       file = fget_raw(fd);
+       if (!file)
+               return ERR_PTR(-EBADF);
 
-       event = f.file->private_data;
-       atomic_long_inc(&event->refcount);
-       fdput(f);
+       if (file->f_op != &perf_fops) {
+               fput(file);
+               return ERR_PTR(-EBADF);
+       }
 
-       return event;
+       return file;
 }
 
 const struct perf_event_attr *perf_event_attrs(struct perf_event *event)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 45dd798bcd37e7bd529e61932e51a30366590626..326a75e884dbf3f46513538861a028c7be459f09 100644 (file)
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -191,14 +191,17 @@ static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5)
        struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        struct perf_event *event;
+       struct file *file;
 
        if (unlikely(index >= array->map.max_entries))
                return -E2BIG;
 
-       event = (struct perf_event *)array->ptrs[index];
-       if (!event)
+       file = (struct file *)array->ptrs[index];
+       if (unlikely(!file))
                return -ENOENT;
 
+       event = file->private_data;
+
        /* make sure event is local and doesn't have pmu::count */
        if (event->oncpu != smp_processor_id() ||
            event->pmu->count)
@@ -228,6 +231,7 @@ static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 index, u64 r4, u64 size)
        void *data = (void *) (long) r4;
        struct perf_sample_data sample_data;
        struct perf_event *event;
+       struct file *file;
        struct perf_raw_record raw = {
                .size = size,
                .data = data,
@@ -236,10 +240,12 @@ static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 index, u64 r4, u64 size)
        if (unlikely(index >= array->map.max_entries))
                return -E2BIG;
 
-       event = (struct perf_event *)array->ptrs[index];
-       if (unlikely(!event))
+       file = (struct file *)array->ptrs[index];
+       if (unlikely(!file))
                return -ENOENT;
 
+       event = file->private_data;
+
        if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE ||
                     event->attr.config != PERF_COUNT_SW_BPF_OUTPUT))
                return -EINVAL;