[GIT PULL] tracing: Minor fixes

[Steven Rostedt]

Linus,

There tracing fixes:

 - Use "nosteal" for ring buffer splice pages
 - Memory leak fix in error path of trace_pid_write()
 - Fix preempt_enable_no_resched() (use preempt_enable()) in ring buffer code


Please pull the latest trace-v5.1-rc6 tree, which can be found at:


  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
trace-v5.1-rc6

Tag SHA1: 18d3b6ef227e69c4620f9ac687bd5200ce5169bc
Head SHA1: d6097c9e4454adf1f8f2c9547c2fa6060d55d952


Jann Horn (1):
      tracing: Fix buffer_ref pipe ops

Peter Zijlstra (1):
      trace: Fix preempt_enable_no_resched() abuse

Wenwen Wang (1):
      tracing: Fix a memory leak by early error exit in trace_pid_write()

----
 fs/splice.c                |  4 ++--
 include/linux/pipe_fs_i.h  |  1 +
 kernel/trace/ring_buffer.c |  2 +-
 kernel/trace/trace.c       | 33 ++++++++++++++++++---------------
 4 files changed, 22 insertions(+), 18 deletions(-)
---------------------------
diff --git a/fs/splice.c b/fs/splice.c
index 3ee7e82df48f..e75807380caa 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -330,8 +330,8 @@ const struct pipe_buf_operations default_pipe_buf_ops = {
        .get = generic_pipe_buf_get,
 };
 
-static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe,
-                                   struct pipe_buffer *buf)
+int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe,
+                            struct pipe_buffer *buf)
 {
        return 1;
 }
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index 787d224ff43e..a830e9a00eb9 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -174,6 +174,7 @@ void free_pipe_info(struct pipe_inode_info *);
 void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
 int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *);
 int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
+int generic_pipe_buf_nosteal(struct pipe_inode_info *, struct pipe_buffer *);
 void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);
 void pipe_buf_mark_unmergeable(struct pipe_buffer *buf);
 
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 41b6f96e5366..4ee8d8aa3d0f 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -762,7 +762,7 @@ u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int 
cpu)
 
        preempt_disable_notrace();
        time = rb_time_stamp(buffer);
-       preempt_enable_no_resched_notrace();
+       preempt_enable_notrace();
 
        return time;
 }
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 21153e64bf1c..46f68fad6373 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -496,8 +496,10 @@ int trace_pid_write(struct trace_pid_list *filtered_pids,
         * not modified.
         */
        pid_list = kmalloc(sizeof(*pid_list), GFP_KERNEL);
-       if (!pid_list)
+       if (!pid_list) {
+               trace_parser_put(&parser);
                return -ENOMEM;
+       }
 
        pid_list->pid_max = READ_ONCE(pid_max);
 
@@ -507,6 +509,7 @@ int trace_pid_write(struct trace_pid_list *filtered_pids,
 
        pid_list->pids = vzalloc((pid_list->pid_max + 7) >> 3);
        if (!pid_list->pids) {
+               trace_parser_put(&parser);
                kfree(pid_list);
                return -ENOMEM;
        }
@@ -7025,19 +7028,23 @@ struct buffer_ref {
        struct ring_buffer      *buffer;
        void                    *page;
        int                     cpu;
-       int                     ref;
+       refcount_t              refcount;
 };
 
+static void buffer_ref_release(struct buffer_ref *ref)
+{
+       if (!refcount_dec_and_test(&ref->refcount))
+               return;
+       ring_buffer_free_read_page(ref->buffer, ref->cpu, ref->page);
+       kfree(ref);
+}
+
 static void buffer_pipe_buf_release(struct pipe_inode_info *pipe,
                                    struct pipe_buffer *buf)
 {
        struct buffer_ref *ref = (struct buffer_ref *)buf->private;
 
-       if (--ref->ref)
-               return;
-
-       ring_buffer_free_read_page(ref->buffer, ref->cpu, ref->page);
-       kfree(ref);
+       buffer_ref_release(ref);
        buf->private = 0;
 }
 
@@ -7046,14 +7053,14 @@ static void buffer_pipe_buf_get(struct pipe_inode_info 
*pipe,
 {
        struct buffer_ref *ref = (struct buffer_ref *)buf->private;
 
-       ref->ref++;
+       refcount_inc(&ref->refcount);
 }
 
 /* Pipe buffer operations for a buffer. */
 static const struct pipe_buf_operations buffer_pipe_buf_ops = {
        .confirm                = generic_pipe_buf_confirm,
        .release                = buffer_pipe_buf_release,
-       .steal                  = generic_pipe_buf_steal,
+       .steal                  = generic_pipe_buf_nosteal,
        .get                    = buffer_pipe_buf_get,
 };
 
@@ -7066,11 +7073,7 @@ static void buffer_spd_release(struct splice_pipe_desc 
*spd, unsigned int i)
        struct buffer_ref *ref =
                (struct buffer_ref *)spd->partial[i].private;
 
-       if (--ref->ref)
-               return;
-
-       ring_buffer_free_read_page(ref->buffer, ref->cpu, ref->page);
-       kfree(ref);
+       buffer_ref_release(ref);
        spd->partial[i].private = 0;
 }
 
@@ -7125,7 +7128,7 @@ tracing_buffers_splice_read(struct file *file, loff_t 
*ppos,
                        break;
                }
 
-               ref->ref = 1;
+               refcount_set(&ref->refcount, 1);
                ref->buffer = iter->trace_buffer->buffer;
                ref->page = ring_buffer_alloc_read_page(ref->buffer, 
iter->cpu_file);
                if (IS_ERR(ref->page)) {