1 files changed, 40 insertions, 77 deletions

diff --git a/drivers/oprofile/buffer_sync.c b/drivers/oprofile/buffer_sync.c
index b55cd23ffdef..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 synchromized */
-
-        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)
@@ -331,28 +319,25 @@ static void add_trace_begin(void)
 
 #define IBS_FETCH_CODE_SIZE     2
 #define IBS_OP_CODE_SIZE        5
-#define IBS_EIP(offset)                         \
-        (((struct op_sample *)&cpu_buf->buffer[(offset)])->eip)
-#define IBS_EVENT(offset)                               \
-        (((struct op_sample *)&cpu_buf->buffer[(offset)])->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->tail_pos);
+        sample = cpu_buffer_read_entry(cpu);
+        if (!sample)
+                goto Error;
+        rip = sample->eip;
 
 #ifdef __LP64__
-        rip += IBS_EVENT(cpu_buf->tail_pos) << 32;
+        rip += sample->event << 32;
 #endif
 
         if (mm) {
@@ -376,8 +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->tail_pos));
-        add_event_entry(IBS_EVENT(cpu_buf->tail_pos));
+        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*/
@@ -385,10 +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->tail_pos));
-                add_event_entry(IBS_EVENT(cpu_buf->tail_pos));
+                sample = cpu_buffer_read_entry(cpu);
+                if (!sample)
+                        goto Error;
+                add_event_entry(sample->eip);
+                add_event_entry(sample->event);
         }
+
+        return;
+
+Error:
+        return;
 }
 
 #endif
@@ -466,33 +458,6 @@ static inline int is_code(unsigned long val)
 }
 
 
-/* "acquire" as many cpu buffer slots as we can */
-static unsigned long get_slots(struct oprofile_cpu_buffer *b)
-{
-        unsigned long head = b->head_pos;
-        unsigned long tail = b->tail_pos;
-
-        /*
-         * Subtle. This resets the persistent last_task
-         * and in_kernel values used for switching notes.
-         * BUT, there is a small window between reading
-         * head_pos, and this call, that means samples
-         * can appear at the new head position, but not
-         * be prefixed with the notes for switching
-         * kernel mode or a task switch. This small hole
-         * can lead to mis-attribution or samples where
-         * we don't know if it's in the kernel or not,
-         * at the start of an event buffer.
-         */
-        cpu_buffer_reset(b);
-
-        if (head >= tail)
-                return head - tail;
-
-        return head + (b->buffer_size - tail);
-}
-
-
 /* Move tasks along towards death. Any tasks on dead_tasks
  * will definitely have no remaining references in any
  * CPU buffers at this point, because we use two lists,
@@ -559,61 +524,61 @@ 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 */
-
-#ifndef CONFIG_OPROFILE_IBS
-        available = get_slots(cpu_buf);
+        cpu_buffer_reset(cpu);
+        available = cpu_buffer_entries(cpu);
 
         for (i = 0; i < available; ++i) {
-#else
-        while (get_slots(cpu_buf)) {
-#endif
-                struct op_sample *s = &cpu_buf->buffer[cpu_buf->tail_pos];
+                struct op_sample *s = cpu_buffer_read_entry(cpu);
+                if (!s)
+                        break;
 
                 if (is_code(s->eip)) {
-                        if (s->event <= CPU_IS_KERNEL) {
+                        switch (s->event) {
+                        case 0:
+                        case CPU_IS_KERNEL:
                                 /* kernel/userspace switch */
                                 in_kernel = s->event;
                                 if (state == sb_buffer_start)
                                         state = sb_sample_start;
                                 add_kernel_ctx_switch(s->event);
-                        } else if (s->event == CPU_TRACE_BEGIN) {
+                                break;
+                        case CPU_TRACE_BEGIN:
                                 state = sb_bt_start;
                                 add_trace_begin();
+                                break;
 #ifdef CONFIG_OPROFILE_IBS
-                        } else if (s->event == IBS_FETCH_BEGIN) {
+                        case IBS_FETCH_BEGIN:
                                 state = sb_bt_start;
-                                add_ibs_begin(cpu_buf, IBS_FETCH_CODE, mm);
-                        } else if (s->event == IBS_OP_BEGIN) {
+                                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
-                        } else {
-                                struct mm_struct *oldmm = mm;
-
+                        default:
                                 /* userspace context switch */
+                                oldmm = mm;
                                 new = (struct task_struct *)s->event;
-
                                 release_mm(oldmm);
                                 mm = take_tasks_mm(new);
                                 if (mm != oldmm)
                                         cookie = get_exec_dcookie(mm);
                                 add_user_ctx_switch(new, cookie);
+                                break;
                         }
                 } else if (state >= sb_bt_start &&
                            !add_sample(mm, s, in_kernel)) {
@@ -622,8 +587,6 @@ void sync_buffer(int cpu)
                                 atomic_inc(&oprofile_stats.bt_lost_no_mapping);
                         }
                 }
-
-                increment_tail(cpu_buf);
         }
         release_mm(mm);