1 files changed, 25 insertions, 40 deletions

diff --git a/drivers/oprofile/buffer_sync.c b/drivers/oprofile/buffer_sync.c
index 944a5832d9e4..737bd9484822 100644
--- a/drivers/oprofile/buffer_sync.c
+++ b/drivers/oprofile/buffer_sync.c
@@ -268,18 +268,6 @@ lookup_dcookie(struct mm_struct *mm, unsigned long addr, off_t *offset)
         return cookie;
 }
 
-static void increment_tail(struct oprofile_cpu_buffer *b)
-{
-        unsigned long new_tail = b->tail_pos + 1;
-
-        rmb();  /* be sure fifo pointers are synchronized */
-
-        if (new_tail < b->buffer_size)
-                b->tail_pos = new_tail;
-        else
-                b->tail_pos = 0;
-}
-
 static unsigned long last_cookie = INVALID_COOKIE;
 
 static void add_cpu_switch(int i)
@@ -331,26 +319,25 @@ static void add_trace_begin(void)
 
 #define IBS_FETCH_CODE_SIZE     2
 #define IBS_OP_CODE_SIZE        5
-#define IBS_EIP(cpu_buf)        ((cpu_buffer_read_entry(cpu_buf))->eip)
-#define IBS_EVENT(cpu_buf)      ((cpu_buffer_read_entry(cpu_buf))->event)
 
 /*
  * Add IBS fetch and op entries to event buffer
  */
-static void add_ibs_begin(struct oprofile_cpu_buffer *cpu_buf, int code,
-                          struct mm_struct *mm)
+static void add_ibs_begin(int cpu, int code, struct mm_struct *mm)
 {
         unsigned long rip;
         int i, count;
         unsigned long ibs_cookie = 0;
         off_t offset;
+        struct op_sample *sample;
 
-        increment_tail(cpu_buf);        /* move to RIP entry */
-
-        rip = IBS_EIP(cpu_buf);
+        sample = cpu_buffer_read_entry(cpu);
+        if (!sample)
+                goto Error;
+        rip = sample->eip;
 
 #ifdef __LP64__
-        rip += IBS_EVENT(cpu_buf) << 32;
+        rip += sample->event << 32;
 #endif
 
         if (mm) {
@@ -374,8 +361,8 @@ static void add_ibs_begin(struct oprofile_cpu_buffer *cpu_buf, int code,
         add_event_entry(offset);        /* Offset from Dcookie */
 
         /* we send the Dcookie offset, but send the raw Linear Add also*/
-        add_event_entry(IBS_EIP(cpu_buf));
-        add_event_entry(IBS_EVENT(cpu_buf));
+        add_event_entry(sample->eip);
+        add_event_entry(sample->event);
 
         if (code == IBS_FETCH_CODE)
                 count = IBS_FETCH_CODE_SIZE;    /*IBS FETCH is 2 int64s*/
@@ -383,10 +370,17 @@ static void add_ibs_begin(struct oprofile_cpu_buffer *cpu_buf, int code,
                 count = IBS_OP_CODE_SIZE;       /*IBS OP is 5 int64s*/
 
         for (i = 0; i < count; i++) {
-                increment_tail(cpu_buf);
-                add_event_entry(IBS_EIP(cpu_buf));
-                add_event_entry(IBS_EVENT(cpu_buf));
+                sample = cpu_buffer_read_entry(cpu);
+                if (!sample)
+                        goto Error;
+                add_event_entry(sample->eip);
+                add_event_entry(sample->event);
         }
+
+        return;
+
+Error:
+        return;
 }
 
 #endif
@@ -530,33 +524,26 @@ typedef enum {
  */
 void sync_buffer(int cpu)
 {
-        struct oprofile_cpu_buffer *cpu_buf = &per_cpu(cpu_buffer, cpu);
         struct mm_struct *mm = NULL;
         struct mm_struct *oldmm;
         struct task_struct *new;
         unsigned long cookie = 0;
         int in_kernel = 1;
         sync_buffer_state state = sb_buffer_start;
-#ifndef CONFIG_OPROFILE_IBS
         unsigned int i;
         unsigned long available;
-#endif
 
         mutex_lock(&buffer_mutex);
 
         add_cpu_switch(cpu);
 
-        /* Remember, only we can modify tail_pos */
-
         cpu_buffer_reset(cpu);
-#ifndef CONFIG_OPROFILE_IBS
-        available = cpu_buffer_entries(cpu_buf);
+        available = cpu_buffer_entries(cpu);
 
         for (i = 0; i < available; ++i) {
-#else
-        while (cpu_buffer_entries(cpu_buf)) {
-#endif
-                struct op_sample *s = cpu_buffer_read_entry(cpu_buf);
+                struct op_sample *s = cpu_buffer_read_entry(cpu);
+                if (!s)
+                        break;
 
                 if (is_code(s->eip)) {
                         switch (s->event) {
@@ -575,11 +562,11 @@ void sync_buffer(int cpu)
 #ifdef CONFIG_OPROFILE_IBS
                         case IBS_FETCH_BEGIN:
                                 state = sb_bt_start;
-                                add_ibs_begin(cpu_buf, IBS_FETCH_CODE, mm);
+                                add_ibs_begin(cpu, IBS_FETCH_CODE, mm);
                                 break;
                         case IBS_OP_BEGIN:
                                 state = sb_bt_start;
-                                add_ibs_begin(cpu_buf, IBS_OP_CODE, mm);
+                                add_ibs_begin(cpu, IBS_OP_CODE, mm);
                                 break;
 #endif
                         default:
@@ -600,8 +587,6 @@ void sync_buffer(int cpu)
                                 atomic_inc(&oprofile_stats.bt_lost_no_mapping);
                         }
                 }
-
-                increment_tail(cpu_buf);
         }
         release_mm(mm);