oprofile: add op_cpu_buffer_get_data()

This function provides access to attached data of a sample. It returns
the size of data including the current value. Also,
op_cpu_buffer_get_size() is available to check if there is data
attached.

Signed-off-by: Robert Richter <robert.richter@amd.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/oprofile/buffer_sync.c b/drivers/oprofile/buffer_sync.c
index d969bb13a252..f9031d31eeb7 100644
--- a/drivers/oprofile/buffer_sync.c
+++ b/drivers/oprofile/buffer_sync.c
@@ -524,6 +524,7 @@ void sync_buffer(int cpu)
 {
         struct mm_struct *mm = NULL;
         struct mm_struct *oldmm;
+        unsigned long val;
         struct task_struct *new;
         unsigned long cookie = 0;
         int in_kernel = 1;
@@ -559,10 +560,11 @@ void sync_buffer(int cpu)
                                         state = sb_sample_start;
                                 add_kernel_ctx_switch(flags & IS_KERNEL);
                         }
-                        if (flags & USER_CTX_SWITCH) {
+                        if (flags & USER_CTX_SWITCH
+                            && op_cpu_buffer_get_data(&entry, &val)) {
                                 /* userspace context switch */
+                                new = (struct task_struct *)val;
                                 oldmm = mm;
-                                new = (struct task_struct *)sample->data[0];
                                 release_mm(oldmm);
                                 mm = take_tasks_mm(new);
                                 if (mm != oldmm)