Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 into for-upstream

Conflicts:

	drivers/uwb/wlp/eda.c

4 files changed, 219 insertions, 181 deletions

diff --git a/drivers/oprofile/buffer_sync.c b/drivers/oprofile/buffer_sync.c
index b55cd23ffdef..65e8294a9e29 100644
--- a/drivers/oprofile/buffer_sync.c
+++ b/drivers/oprofile/buffer_sync.c
@@ -200,7 +200,7 @@ static inline unsigned long fast_get_dcookie(struct path *path)
 {
         unsigned long cookie;
 
-        if (path->dentry->d_cookie)
+        if (path->dentry->d_flags & DCACHE_COOKIE)
                 return (unsigned long)path->dentry;
         get_dcookie(path, &cookie);
         return cookie;
@@ -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);
 
diff --git a/drivers/oprofile/cpu_buffer.c b/drivers/oprofile/cpu_buffer.c
index 01d38e78cde1..61090969158f 100644
--- a/drivers/oprofile/cpu_buffer.c
+++ b/drivers/oprofile/cpu_buffer.c
@@ -28,6 +28,25 @@
 #include "buffer_sync.h"
 #include "oprof.h"
 
+#define OP_BUFFER_FLAGS 0
+
+/*
+ * Read and write access is using spin locking. Thus, writing to the
+ * buffer by NMI handler (x86) could occur also during critical
+ * sections when reading the buffer. To avoid this, there are 2
+ * buffers for independent read and write access. Read access is in
+ * process context only, write access only in the NMI handler. If the
+ * read buffer runs empty, both buffers are swapped atomically. There
+ * is potentially a small window during swapping where the buffers are
+ * disabled and samples could be lost.
+ *
+ * Using 2 buffers is a little bit overhead, but the solution is clear
+ * and does not require changes in the ring buffer implementation. It
+ * can be changed to a single buffer solution when the ring buffer
+ * access is implemented as non-locking atomic code.
+ */
+struct ring_buffer *op_ring_buffer_read;
+struct ring_buffer *op_ring_buffer_write;
 DEFINE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer);
 
 static void wq_sync_buffer(struct work_struct *work);
@@ -37,12 +56,12 @@ static int work_enabled;
 
 void free_cpu_buffers(void)
 {
-        int i;
-
-        for_each_possible_cpu(i) {
-                vfree(per_cpu(cpu_buffer, i).buffer);
-                per_cpu(cpu_buffer, i).buffer = NULL;
-        }
+        if (op_ring_buffer_read)
+                ring_buffer_free(op_ring_buffer_read);
+        op_ring_buffer_read = NULL;
+        if (op_ring_buffer_write)
+                ring_buffer_free(op_ring_buffer_write);
+        op_ring_buffer_write = NULL;
 }
 
 unsigned long oprofile_get_cpu_buffer_size(void)
@@ -64,14 +83,16 @@ int alloc_cpu_buffers(void)
 
         unsigned long buffer_size = fs_cpu_buffer_size;
 
+        op_ring_buffer_read = ring_buffer_alloc(buffer_size, OP_BUFFER_FLAGS);
+        if (!op_ring_buffer_read)
+                goto fail;
+        op_ring_buffer_write = ring_buffer_alloc(buffer_size, OP_BUFFER_FLAGS);
+        if (!op_ring_buffer_write)
+                goto fail;
+
         for_each_possible_cpu(i) {
                 struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);
 
-                b->buffer = vmalloc_node(sizeof(struct op_sample) * buffer_size,
-                        cpu_to_node(i));
-                if (!b->buffer)
-                        goto fail;
-
                 b->last_task = NULL;
                 b->last_is_kernel = -1;
                 b->tracing = 0;
@@ -124,57 +145,31 @@ void end_cpu_work(void)
         flush_scheduled_work();
 }
 
-/* Resets the cpu buffer to a sane state. */
-void cpu_buffer_reset(struct oprofile_cpu_buffer *cpu_buf)
-{
-        /* reset these to invalid values; the next sample
-         * collected will populate the buffer with proper
-         * values to initialize the buffer
-         */
-        cpu_buf->last_is_kernel = -1;
-        cpu_buf->last_task = NULL;
-}
-
-/* compute number of available slots in cpu_buffer queue */
-static unsigned long nr_available_slots(struct oprofile_cpu_buffer const *b)
+static inline int
+add_sample(struct oprofile_cpu_buffer *cpu_buf,
+           unsigned long pc, unsigned long event)
 {
-        unsigned long head = b->head_pos;
-        unsigned long tail = b->tail_pos;
+        struct op_entry entry;
+        int ret;
 
-        if (tail > head)
-                return (tail - head) - 1;
+        ret = cpu_buffer_write_entry(&entry);
+        if (ret)
+                return ret;
 
-        return tail + (b->buffer_size - head) - 1;
-}
+        entry.sample->eip = pc;
+        entry.sample->event = event;
 
-static void increment_head(struct oprofile_cpu_buffer *b)
-{
-        unsigned long new_head = b->head_pos + 1;
-
-        /* Ensure anything written to the slot before we
-         * increment is visible */
-        wmb();
-
-        if (new_head < b->buffer_size)
-                b->head_pos = new_head;
-        else
-                b->head_pos = 0;
-}
+        ret = cpu_buffer_write_commit(&entry);
+        if (ret)
+                return ret;
 
-static inline void
-add_sample(struct oprofile_cpu_buffer *cpu_buf,
-           unsigned long pc, unsigned long event)
-{
-        struct op_sample *entry = &cpu_buf->buffer[cpu_buf->head_pos];
-        entry->eip = pc;
-        entry->event = event;
-        increment_head(cpu_buf);
+        return 0;
 }
 
-static inline void
+static inline int
 add_code(struct oprofile_cpu_buffer *buffer, unsigned long value)
 {
-        add_sample(buffer, ESCAPE_CODE, value);
+        return add_sample(buffer, ESCAPE_CODE, value);
 }
 
 /* This must be safe from any context. It's safe writing here
@@ -198,11 +193,6 @@ static int log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc,
                 return 0;
         }
 
-        if (nr_available_slots(cpu_buf) < 3) {
-                cpu_buf->sample_lost_overflow++;
-                return 0;
-        }
-
         is_kernel = !!is_kernel;
 
         task = current;
@@ -210,26 +200,29 @@ static int log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc,
         /* notice a switch from user->kernel or vice versa */
         if (cpu_buf->last_is_kernel != is_kernel) {
                 cpu_buf->last_is_kernel = is_kernel;
-                add_code(cpu_buf, is_kernel);
+                if (add_code(cpu_buf, is_kernel))
+                        goto fail;
         }
 
         /* notice a task switch */
         if (cpu_buf->last_task != task) {
                 cpu_buf->last_task = task;
-                add_code(cpu_buf, (unsigned long)task);
+                if (add_code(cpu_buf, (unsigned long)task))
+                        goto fail;
         }
 
-        add_sample(cpu_buf, pc, event);
+        if (add_sample(cpu_buf, pc, event))
+                goto fail;
+
         return 1;
+
+fail:
+        cpu_buf->sample_lost_overflow++;
+        return 0;
 }
 
 static int oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf)
 {
-        if (nr_available_slots(cpu_buf) < 4) {
-                cpu_buf->sample_lost_overflow++;
-                return 0;
-        }
-
         add_code(cpu_buf, CPU_TRACE_BEGIN);
         cpu_buf->tracing = 1;
         return 1;
@@ -253,8 +246,10 @@ void oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,
         if (!oprofile_begin_trace(cpu_buf))
                 return;
 
-        /* if log_sample() fail we can't backtrace since we lost the source
-         * of this event */
+        /*
+         * if log_sample() fail we can't backtrace since we lost the
+         * source of this event
+         */
         if (log_sample(cpu_buf, pc, is_kernel, event))
                 oprofile_ops.backtrace(regs, backtrace_depth);
         oprofile_end_trace(cpu_buf);
@@ -272,49 +267,55 @@ void oprofile_add_sample(struct pt_regs * const regs, unsigned long event)
 
 #define MAX_IBS_SAMPLE_SIZE 14
 
-void oprofile_add_ibs_sample(struct pt_regs *const regs,
-                             unsigned int *const ibs_sample, int ibs_code)
+void oprofile_add_ibs_sample(struct pt_regs * const regs,
+                             unsigned int * const ibs_sample, int ibs_code)
 {
         int is_kernel = !user_mode(regs);
         struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
         struct task_struct *task;
+        int fail = 0;
 
         cpu_buf->sample_received++;
 
-        if (nr_available_slots(cpu_buf) < MAX_IBS_SAMPLE_SIZE) {
-                /* we can't backtrace since we lost the source of this event */
-                cpu_buf->sample_lost_overflow++;
-                return;
-        }
-
         /* notice a switch from user->kernel or vice versa */
         if (cpu_buf->last_is_kernel != is_kernel) {
+                if (add_code(cpu_buf, is_kernel))
+                        goto fail;
                 cpu_buf->last_is_kernel = is_kernel;
-                add_code(cpu_buf, is_kernel);
         }
 
         /* notice a task switch */
         if (!is_kernel) {
                 task = current;
                 if (cpu_buf->last_task != task) {
+                        if (add_code(cpu_buf, (unsigned long)task))
+                                goto fail;
                         cpu_buf->last_task = task;
-                        add_code(cpu_buf, (unsigned long)task);
                 }
         }
 
-        add_code(cpu_buf, ibs_code);
-        add_sample(cpu_buf, ibs_sample[0], ibs_sample[1]);
-        add_sample(cpu_buf, ibs_sample[2], ibs_sample[3]);
-        add_sample(cpu_buf, ibs_sample[4], ibs_sample[5]);
+        fail = fail || add_code(cpu_buf, ibs_code);
+        fail = fail || add_sample(cpu_buf, ibs_sample[0], ibs_sample[1]);
+        fail = fail || add_sample(cpu_buf, ibs_sample[2], ibs_sample[3]);
+        fail = fail || add_sample(cpu_buf, ibs_sample[4], ibs_sample[5]);
 
         if (ibs_code == IBS_OP_BEGIN) {
-                add_sample(cpu_buf, ibs_sample[6], ibs_sample[7]);
-                add_sample(cpu_buf, ibs_sample[8], ibs_sample[9]);
-                add_sample(cpu_buf, ibs_sample[10], ibs_sample[11]);
+                fail = fail || add_sample(cpu_buf, ibs_sample[6], ibs_sample[7]);
+                fail = fail || add_sample(cpu_buf, ibs_sample[8], ibs_sample[9]);
+                fail = fail || add_sample(cpu_buf, ibs_sample[10], ibs_sample[11]);
         }
 
+        if (fail)
+                goto fail;
+
         if (backtrace_depth)
                 oprofile_ops.backtrace(regs, backtrace_depth);
+
+        return;
+
+fail:
+        cpu_buf->sample_lost_overflow++;
+        return;
 }
 
 #endif
@@ -332,21 +333,21 @@ void oprofile_add_trace(unsigned long pc)
         if (!cpu_buf->tracing)
                 return;
 
-        if (nr_available_slots(cpu_buf) < 1) {
-                cpu_buf->tracing = 0;
-                cpu_buf->sample_lost_overflow++;
-                return;
-        }
+        /*
+         * broken frame can give an eip with the same value as an
+         * escape code, abort the trace if we get it
+         */
+        if (pc == ESCAPE_CODE)
+                goto fail;
 
-        /* broken frame can give an eip with the same value as an escape code,
-         * abort the trace if we get it */
-        if (pc == ESCAPE_CODE) {
-                cpu_buf->tracing = 0;
-                cpu_buf->backtrace_aborted++;
-                return;
-        }
+        if (add_sample(cpu_buf, pc, 0))
+                goto fail;
 
-        add_sample(cpu_buf, pc, 0);
+        return;
+fail:
+        cpu_buf->tracing = 0;
+        cpu_buf->backtrace_aborted++;
+        return;
 }
 
 /*
diff --git a/drivers/oprofile/cpu_buffer.h b/drivers/oprofile/cpu_buffer.h
index d3cc26264db5..aacb0f0bc566 100644
--- a/drivers/oprofile/cpu_buffer.h
+++ b/drivers/oprofile/cpu_buffer.h
@@ -15,6 +15,7 @@
 #include <linux/workqueue.h>
 #include <linux/cache.h>
 #include <linux/sched.h>
+#include <linux/ring_buffer.h>
 
 struct task_struct;
 
@@ -32,6 +33,12 @@ struct op_sample {
         unsigned long event;
 };
 
+struct op_entry {
+        struct ring_buffer_event *event;
+        struct op_sample *sample;
+        unsigned long irq_flags;
+};
+
 struct oprofile_cpu_buffer {
         volatile unsigned long head_pos;
         volatile unsigned long tail_pos;
@@ -39,7 +46,6 @@ struct oprofile_cpu_buffer {
         struct task_struct *last_task;
         int last_is_kernel;
         int tracing;
-        struct op_sample *buffer;
         unsigned long sample_received;
         unsigned long sample_lost_overflow;
         unsigned long backtrace_aborted;
@@ -48,9 +54,68 @@ struct oprofile_cpu_buffer {
         struct delayed_work work;
 };
 
+extern struct ring_buffer *op_ring_buffer_read;
+extern struct ring_buffer *op_ring_buffer_write;
 DECLARE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer);
 
-void cpu_buffer_reset(struct oprofile_cpu_buffer *cpu_buf);
+/*
+ * Resets the cpu buffer to a sane state.
+ *
+ * reset these to invalid values; the next sample collected will
+ * populate the buffer with proper values to initialize the buffer
+ */
+static inline void cpu_buffer_reset(int cpu)
+{
+        struct oprofile_cpu_buffer *cpu_buf = &per_cpu(cpu_buffer, cpu);
+
+        cpu_buf->last_is_kernel = -1;
+        cpu_buf->last_task = NULL;
+}
+
+static inline int cpu_buffer_write_entry(struct op_entry *entry)
+{
+        entry->event = ring_buffer_lock_reserve(op_ring_buffer_write,
+                                                sizeof(struct op_sample),
+                                                &entry->irq_flags);
+        if (entry->event)
+                entry->sample = ring_buffer_event_data(entry->event);
+        else
+                entry->sample = NULL;
+
+        if (!entry->sample)
+                return -ENOMEM;
+
+        return 0;
+}
+
+static inline int cpu_buffer_write_commit(struct op_entry *entry)
+{
+        return ring_buffer_unlock_commit(op_ring_buffer_write, entry->event,
+                                         entry->irq_flags);
+}
+
+static inline struct op_sample *cpu_buffer_read_entry(int cpu)
+{
+        struct ring_buffer_event *e;
+        e = ring_buffer_consume(op_ring_buffer_read, cpu, NULL);
+        if (e)
+                return ring_buffer_event_data(e);
+        if (ring_buffer_swap_cpu(op_ring_buffer_read,
+                                 op_ring_buffer_write,
+                                 cpu))
+                return NULL;
+        e = ring_buffer_consume(op_ring_buffer_read, cpu, NULL);
+        if (e)
+                return ring_buffer_event_data(e);
+        return NULL;
+}
+
+/* "acquire" as many cpu buffer slots as we can */
+static inline unsigned long cpu_buffer_entries(int cpu)
+{
+        return ring_buffer_entries_cpu(op_ring_buffer_read, cpu)
+                + ring_buffer_entries_cpu(op_ring_buffer_write, cpu);
+}
 
 /* transient events for the CPU buffer -> event buffer */
 #define CPU_IS_KERNEL 1
diff --git a/drivers/oprofile/oprofile_files.c b/drivers/oprofile/oprofile_files.c
index cc106d503ace..d8201998b0b7 100644
--- a/drivers/oprofile/oprofile_files.c
+++ b/drivers/oprofile/oprofile_files.c
@@ -14,9 +14,13 @@
 #include "oprofile_stats.h"
 #include "oprof.h"
 
-unsigned long fs_buffer_size = 131072;
-unsigned long fs_cpu_buffer_size = 8192;
-unsigned long fs_buffer_watershed = 32768; /* FIXME: tune */
+#define FS_BUFFER_SIZE_DEFAULT          131072
+#define FS_CPU_BUFFER_SIZE_DEFAULT      8192
+#define FS_BUFFER_WATERSHED_DEFAULT     32768   /* FIXME: tune */
+
+unsigned long fs_buffer_size;
+unsigned long fs_cpu_buffer_size;
+unsigned long fs_buffer_watershed;
 
 static ssize_t depth_read(struct file *file, char __user *buf, size_t count, loff_t *offset)
 {
@@ -120,6 +124,11 @@ static const struct file_operations dump_fops = {
 
 void oprofile_create_files(struct super_block *sb, struct dentry *root)
 {
+        /* reinitialize default values */
+        fs_buffer_size =        FS_BUFFER_SIZE_DEFAULT;
+        fs_cpu_buffer_size =    FS_CPU_BUFFER_SIZE_DEFAULT;
+        fs_buffer_watershed =   FS_BUFFER_WATERSHED_DEFAULT;
+
         oprofilefs_create_file(sb, root, "enable", &enable_fops);
         oprofilefs_create_file_perm(sb, root, "dump", &dump_fops, 0666);
         oprofilefs_create_file(sb, root, "buffer", &event_buffer_fops);