Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (24 commits)
  tracing/urgent: warn in case of ftrace_start_up inbalance
  tracing/urgent: fix unbalanced ftrace_start_up
  function-graph: add stack frame test
  function-graph: disable when both x86_32 and optimize for size are configured
  ring-buffer: have benchmark test print to trace buffer
  ring-buffer: do not grab locks in nmi
  ring-buffer: add locks around rb_per_cpu_empty
  ring-buffer: check for less than two in size allocation
  ring-buffer: remove useless compile check for buffer_page size
  ring-buffer: remove useless warn on check
  ring-buffer: use BUF_PAGE_HDR_SIZE in calculating index
  tracing: update sample event documentation
  tracing/filters: fix race between filter setting and module unload
  tracing/filters: free filter_string in destroy_preds()
  ring-buffer: use commit counters for commit pointer accounting
  ring-buffer: remove unused variable
  ring-buffer: have benchmark test handle discarded events
  ring-buffer: prevent adding write in discarded area
  tracing/filters: strloc should be unsigned short
  tracing/filters: operand can be negative
  ...

Fix up kmemcheck-induced conflict in kernel/trace/ring_buffer.c manually

1 files changed, 193 insertions, 118 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index dc4dc70171ce..04dac2638258 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -206,6 +206,7 @@ EXPORT_SYMBOL_GPL(tracing_is_on);
 #define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array))
 #define RB_ALIGNMENT            4U
 #define RB_MAX_SMALL_DATA       (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX)
+#define RB_EVNT_MIN_SIZE        8U      /* two 32bit words */
 
 /* define RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */
 #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX
@@ -415,6 +416,8 @@ struct ring_buffer_per_cpu {
         unsigned long                   overrun;
         unsigned long                   read;
         local_t                         entries;
+        local_t                         committing;
+        local_t                         commits;
         u64                             write_stamp;
         u64                             read_stamp;
         atomic_t                        record_disabled;
@@ -618,12 +621,6 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer)
         kfree(cpu_buffer);
 }
 
-/*
- * Causes compile errors if the struct buffer_page gets bigger
- * than the struct page.
- */
-extern int ring_buffer_page_too_big(void);
-
 #ifdef CONFIG_HOTPLUG_CPU
 static int rb_cpu_notify(struct notifier_block *self,
                          unsigned long action, void *hcpu);
@@ -646,11 +643,6 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags,
         int bsize;
         int cpu;
 
-        /* Paranoid! Optimizes out when all is well */
-        if (sizeof(struct buffer_page) > sizeof(struct page))
-                ring_buffer_page_too_big();
-
-
         /* keep it in its own cache line */
         buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()),
                          GFP_KERNEL);
@@ -666,8 +658,8 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags,
         buffer->reader_lock_key = key;
 
         /* need at least two pages */
-        if (buffer->pages == 1)
-                buffer->pages++;
+        if (buffer->pages < 2)
+                buffer->pages = 2;
 
         /*
          * In case of non-hotplug cpu, if the ring-buffer is allocated
@@ -1011,12 +1003,12 @@ rb_event_index(struct ring_buffer_event *event)
 {
         unsigned long addr = (unsigned long)event;
 
-        return (addr & ~PAGE_MASK) - (PAGE_SIZE - BUF_PAGE_SIZE);
+        return (addr & ~PAGE_MASK) - BUF_PAGE_HDR_SIZE;
 }
 
 static inline int
-rb_is_commit(struct ring_buffer_per_cpu *cpu_buffer,
-             struct ring_buffer_event *event)
+rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer,
+                   struct ring_buffer_event *event)
 {
         unsigned long addr = (unsigned long)event;
         unsigned long index;
@@ -1029,31 +1021,6 @@ rb_is_commit(struct ring_buffer_per_cpu *cpu_buffer,
 }
 
 static void
-rb_set_commit_event(struct ring_buffer_per_cpu *cpu_buffer,
-                    struct ring_buffer_event *event)
-{
-        unsigned long addr = (unsigned long)event;
-        unsigned long index;
-
-        index = rb_event_index(event);
-        addr &= PAGE_MASK;
-
-        while (cpu_buffer->commit_page->page != (void *)addr) {
-                if (RB_WARN_ON(cpu_buffer,
-                          cpu_buffer->commit_page == cpu_buffer->tail_page))
-                        return;
-                cpu_buffer->commit_page->page->commit =
-                        cpu_buffer->commit_page->write;
-                rb_inc_page(cpu_buffer, &cpu_buffer->commit_page);
-                cpu_buffer->write_stamp =
-                        cpu_buffer->commit_page->page->time_stamp;
-        }
-
-        /* Now set the commit to the event's index */
-        local_set(&cpu_buffer->commit_page->page->commit, index);
-}
-
-static void
 rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer)
 {
         /*
@@ -1171,6 +1138,60 @@ static unsigned rb_calculate_event_length(unsigned length)
         return length;
 }
 
+static inline void
+rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer,
+              struct buffer_page *tail_page,
+              unsigned long tail, unsigned long length)
+{
+        struct ring_buffer_event *event;
+
+        /*
+         * Only the event that crossed the page boundary
+         * must fill the old tail_page with padding.
+         */
+        if (tail >= BUF_PAGE_SIZE) {
+                local_sub(length, &tail_page->write);
+                return;
+        }
+
+        event = __rb_page_index(tail_page, tail);
+        kmemcheck_annotate_bitfield(event, bitfield);
+
+        /*
+         * If this event is bigger than the minimum size, then
+         * we need to be careful that we don't subtract the
+         * write counter enough to allow another writer to slip
+         * in on this page.
+         * We put in a discarded commit instead, to make sure
+         * that this space is not used again.
+         *
+         * If we are less than the minimum size, we don't need to
+         * worry about it.
+         */
+        if (tail > (BUF_PAGE_SIZE - RB_EVNT_MIN_SIZE)) {
+                /* No room for any events */
+
+                /* Mark the rest of the page with padding */
+                rb_event_set_padding(event);
+
+                /* Set the write back to the previous setting */
+                local_sub(length, &tail_page->write);
+                return;
+        }
+
+        /* Put in a discarded event */
+        event->array[0] = (BUF_PAGE_SIZE - tail) - RB_EVNT_HDR_SIZE;
+        event->type_len = RINGBUF_TYPE_PADDING;
+        /* time delta must be non zero */
+        event->time_delta = 1;
+        /* Account for this as an entry */
+        local_inc(&tail_page->entries);
+        local_inc(&cpu_buffer->entries);
+
+        /* Set write to end of buffer */
+        length = (tail + length) - BUF_PAGE_SIZE;
+        local_sub(length, &tail_page->write);
+}
 
 static struct ring_buffer_event *
 rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
@@ -1180,7 +1201,6 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
 {
         struct buffer_page *next_page, *head_page, *reader_page;
         struct ring_buffer *buffer = cpu_buffer->buffer;
-        struct ring_buffer_event *event;
         bool lock_taken = false;
         unsigned long flags;
 
@@ -1265,27 +1285,7 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
                 cpu_buffer->tail_page->page->time_stamp = *ts;
         }
 
-        /*
-         * The actual tail page has moved forward.
-         */
-        if (tail < BUF_PAGE_SIZE) {
-                /* Mark the rest of the page with padding */
-                event = __rb_page_index(tail_page, tail);
-                kmemcheck_annotate_bitfield(event, bitfield);
-                rb_event_set_padding(event);
-        }
-
-        /* Set the write back to the previous setting */
-        local_sub(length, &tail_page->write);
-
-        /*
-         * If this was a commit entry that failed,
-         * increment that too
-         */
-        if (tail_page == cpu_buffer->commit_page &&
-            tail == rb_commit_index(cpu_buffer)) {
-                rb_set_commit_to_write(cpu_buffer);
-        }
+        rb_reset_tail(cpu_buffer, tail_page, tail, length);
 
         __raw_spin_unlock(&cpu_buffer->lock);
         local_irq_restore(flags);
@@ -1295,7 +1295,7 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
 
  out_reset:
         /* reset write */
-        local_sub(length, &tail_page->write);
+        rb_reset_tail(cpu_buffer, tail_page, tail, length);
 
         if (likely(lock_taken))
                 __raw_spin_unlock(&cpu_buffer->lock);
@@ -1325,9 +1325,6 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
 
         /* We reserved something on the buffer */
 
-        if (RB_WARN_ON(cpu_buffer, write > BUF_PAGE_SIZE))
-                return NULL;
-
         event = __rb_page_index(tail_page, tail);
         kmemcheck_annotate_bitfield(event, bitfield);
         rb_update_event(event, type, length);
@@ -1337,11 +1334,11 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
                 local_inc(&tail_page->entries);
 
         /*
-         * If this is a commit and the tail is zero, then update
-         * this page's time stamp.
+         * If this is the first commit on the page, then update
+         * its timestamp.
          */
-        if (!tail && rb_is_commit(cpu_buffer, event))
-                cpu_buffer->commit_page->page->time_stamp = *ts;
+        if (!tail)
+                tail_page->page->time_stamp = *ts;
 
         return event;
 }
@@ -1410,16 +1407,16 @@ rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer,
                 return -EAGAIN;
 
         /* Only a commited time event can update the write stamp */
-        if (rb_is_commit(cpu_buffer, event)) {
+        if (rb_event_is_commit(cpu_buffer, event)) {
                 /*
-                 * If this is the first on the page, then we need to
-                 * update the page itself, and just put in a zero.
+                 * If this is the first on the page, then it was
+                 * updated with the page itself. Try to discard it
+                 * and if we can't just make it zero.
                  */
                 if (rb_event_index(event)) {
                         event->time_delta = *delta & TS_MASK;
                         event->array[0] = *delta >> TS_SHIFT;
                 } else {
-                        cpu_buffer->commit_page->page->time_stamp = *ts;
                         /* try to discard, since we do not need this */
                         if (!rb_try_to_discard(cpu_buffer, event)) {
                                 /* nope, just zero it */
@@ -1445,6 +1442,44 @@ rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer,
         return ret;
 }
 
+static void rb_start_commit(struct ring_buffer_per_cpu *cpu_buffer)
+{
+        local_inc(&cpu_buffer->committing);
+        local_inc(&cpu_buffer->commits);
+}
+
+static void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer)
+{
+        unsigned long commits;
+
+        if (RB_WARN_ON(cpu_buffer,
+                       !local_read(&cpu_buffer->committing)))
+                return;
+
+ again:
+        commits = local_read(&cpu_buffer->commits);
+        /* synchronize with interrupts */
+        barrier();
+        if (local_read(&cpu_buffer->committing) == 1)
+                rb_set_commit_to_write(cpu_buffer);
+
+        local_dec(&cpu_buffer->committing);
+
+        /* synchronize with interrupts */
+        barrier();
+
+        /*
+         * Need to account for interrupts coming in between the
+         * updating of the commit page and the clearing of the
+         * committing counter.
+         */
+        if (unlikely(local_read(&cpu_buffer->commits) != commits) &&
+            !local_read(&cpu_buffer->committing)) {
+                local_inc(&cpu_buffer->committing);
+                goto again;
+        }
+}
+
 static struct ring_buffer_event *
 rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer,
                       unsigned long length)
@@ -1454,6 +1489,8 @@ rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer,
         int commit = 0;
         int nr_loops = 0;
 
+        rb_start_commit(cpu_buffer);
+
         length = rb_calculate_event_length(length);
  again:
         /*
@@ -1466,7 +1503,7 @@ rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer,
          * Bail!
          */
         if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000))
-                return NULL;
+                goto out_fail;
 
         ts = rb_time_stamp(cpu_buffer->buffer, cpu_buffer->cpu);
 
@@ -1497,7 +1534,7 @@ rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer,
 
                         commit = rb_add_time_stamp(cpu_buffer, &ts, &delta);
                         if (commit == -EBUSY)
-                                return NULL;
+                                goto out_fail;
 
                         if (commit == -EAGAIN)
                                 goto again;
@@ -1511,28 +1548,19 @@ rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer,
         if (unlikely(PTR_ERR(event) == -EAGAIN))
                 goto again;
 
-        if (!event) {
-                if (unlikely(commit))
-                        /*
-                         * Ouch! We needed a timestamp and it was commited. But
-                         * we didn't get our event reserved.
-                         */
-                        rb_set_commit_to_write(cpu_buffer);
-                return NULL;
-        }
+        if (!event)
+                goto out_fail;
 
-        /*
-         * If the timestamp was commited, make the commit our entry
-         * now so that we will update it when needed.
-         */
-        if (unlikely(commit))
-                rb_set_commit_event(cpu_buffer, event);
-        else if (!rb_is_commit(cpu_buffer, event))
+        if (!rb_event_is_commit(cpu_buffer, event))
                 delta = 0;
 
         event->time_delta = delta;
 
         return event;
+
+ out_fail:
+        rb_end_commit(cpu_buffer);
+        return NULL;
 }
 
 #define TRACE_RECURSIVE_DEPTH 16
@@ -1642,13 +1670,14 @@ static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer,
 {
         local_inc(&cpu_buffer->entries);
 
-        /* Only process further if we own the commit */
-        if (!rb_is_commit(cpu_buffer, event))
-                return;
-
-        cpu_buffer->write_stamp += event->time_delta;
+        /*
+         * The event first in the commit queue updates the
+         * time stamp.
+         */
+        if (rb_event_is_commit(cpu_buffer, event))
+                cpu_buffer->write_stamp += event->time_delta;
 
-        rb_set_commit_to_write(cpu_buffer);
+        rb_end_commit(cpu_buffer);
 }
 
 /**
@@ -1737,15 +1766,15 @@ void ring_buffer_discard_commit(struct ring_buffer *buffer,
         /* The event is discarded regardless */
         rb_event_discard(event);
 
+        cpu = smp_processor_id();
+        cpu_buffer = buffer->buffers[cpu];
+
         /*
          * This must only be called if the event has not been
          * committed yet. Thus we can assume that preemption
          * is still disabled.
          */
-        RB_WARN_ON(buffer, preemptible());
-
-        cpu = smp_processor_id();
-        cpu_buffer = buffer->buffers[cpu];
+        RB_WARN_ON(buffer, !local_read(&cpu_buffer->committing));
 
         if (!rb_try_to_discard(cpu_buffer, event))
                 goto out;
@@ -1756,13 +1785,7 @@ void ring_buffer_discard_commit(struct ring_buffer *buffer,
          */
         local_inc(&cpu_buffer->entries);
  out:
-        /*
-         * If a write came in and pushed the tail page
-         * we still need to update the commit pointer
-         * if we were the commit.
-         */
-        if (rb_is_commit(cpu_buffer, event))
-                rb_set_commit_to_write(cpu_buffer);
+        rb_end_commit(cpu_buffer);
 
         trace_recursive_unlock();
 
@@ -2446,6 +2469,21 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
 }
 EXPORT_SYMBOL_GPL(ring_buffer_iter_peek);
 
+static inline int rb_ok_to_lock(void)
+{
+        /*
+         * If an NMI die dumps out the content of the ring buffer
+         * do not grab locks. We also permanently disable the ring
+         * buffer too. A one time deal is all you get from reading
+         * the ring buffer from an NMI.
+         */
+        if (likely(!in_nmi() && !oops_in_progress))
+                return 1;
+
+        tracing_off_permanent();
+        return 0;
+}
+
 /**
  * ring_buffer_peek - peek at the next event to be read
  * @buffer: The ring buffer to read
@@ -2461,14 +2499,20 @@ ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts)
         struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
         struct ring_buffer_event *event;
         unsigned long flags;
+        int dolock;
 
         if (!cpumask_test_cpu(cpu, buffer->cpumask))
                 return NULL;
 
+        dolock = rb_ok_to_lock();
  again:
-        spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+        local_irq_save(flags);
+        if (dolock)
+                spin_lock(&cpu_buffer->reader_lock);
         event = rb_buffer_peek(buffer, cpu, ts);
-        spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+        if (dolock)
+                spin_unlock(&cpu_buffer->reader_lock);
+        local_irq_restore(flags);
 
         if (event && event->type_len == RINGBUF_TYPE_PADDING) {
                 cpu_relax();
@@ -2520,6 +2564,9 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts)
         struct ring_buffer_per_cpu *cpu_buffer;
         struct ring_buffer_event *event = NULL;
         unsigned long flags;
+        int dolock;
+
+        dolock = rb_ok_to_lock();
 
  again:
         /* might be called in atomic */
@@ -2529,7 +2576,9 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts)
                 goto out;
 
         cpu_buffer = buffer->buffers[cpu];
-        spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+        local_irq_save(flags);
+        if (dolock)
+                spin_lock(&cpu_buffer->reader_lock);
 
         event = rb_buffer_peek(buffer, cpu, ts);
         if (!event)
@@ -2538,7 +2587,9 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts)
         rb_advance_reader(cpu_buffer);
 
  out_unlock:
-        spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+        if (dolock)
+                spin_unlock(&cpu_buffer->reader_lock);
+        local_irq_restore(flags);
 
  out:
         preempt_enable();
@@ -2680,6 +2731,8 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer)
         cpu_buffer->overrun = 0;
         cpu_buffer->read = 0;
         local_set(&cpu_buffer->entries, 0);
+        local_set(&cpu_buffer->committing, 0);
+        local_set(&cpu_buffer->commits, 0);
 
         cpu_buffer->write_stamp = 0;
         cpu_buffer->read_stamp = 0;
@@ -2734,12 +2787,25 @@ EXPORT_SYMBOL_GPL(ring_buffer_reset);
 int ring_buffer_empty(struct ring_buffer *buffer)
 {
         struct ring_buffer_per_cpu *cpu_buffer;
+        unsigned long flags;
+        int dolock;
         int cpu;
+        int ret;
+
+        dolock = rb_ok_to_lock();
 
         /* yes this is racy, but if you don't like the race, lock the buffer */
         for_each_buffer_cpu(buffer, cpu) {
                 cpu_buffer = buffer->buffers[cpu];
-                if (!rb_per_cpu_empty(cpu_buffer))
+                local_irq_save(flags);
+                if (dolock)
+                        spin_lock(&cpu_buffer->reader_lock);
+                ret = rb_per_cpu_empty(cpu_buffer);
+                if (dolock)
+                        spin_unlock(&cpu_buffer->reader_lock);
+                local_irq_restore(flags);
+
+                if (!ret)
                         return 0;
         }
 
@@ -2755,14 +2821,23 @@ EXPORT_SYMBOL_GPL(ring_buffer_empty);
 int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu)
 {
         struct ring_buffer_per_cpu *cpu_buffer;
+        unsigned long flags;
+        int dolock;
         int ret;
 
         if (!cpumask_test_cpu(cpu, buffer->cpumask))
                 return 1;
 
+        dolock = rb_ok_to_lock();
+
         cpu_buffer = buffer->buffers[cpu];
+        local_irq_save(flags);
+        if (dolock)
+                spin_lock(&cpu_buffer->reader_lock);
         ret = rb_per_cpu_empty(cpu_buffer);
-
+        if (dolock)
+                spin_unlock(&cpu_buffer->reader_lock);
+        local_irq_restore(flags);
 
         return ret;
 }
@@ -3108,7 +3183,7 @@ static int rb_cpu_notify(struct notifier_block *self,
         switch (action) {
         case CPU_UP_PREPARE:
         case CPU_UP_PREPARE_FROZEN:
-                if (cpu_isset(cpu, *buffer->cpumask))
+                if (cpumask_test_cpu(cpu, buffer->cpumask))
                         return NOTIFY_OK;
 
                 buffer->buffers[cpu] =
@@ -3119,7 +3194,7 @@ static int rb_cpu_notify(struct notifier_block *self,
                         return NOTIFY_OK;
                 }
                 smp_wmb();
-                cpu_set(cpu, *buffer->cpumask);
+                cpumask_set_cpu(cpu, buffer->cpumask);
                 break;
         case CPU_DOWN_PREPARE:
         case CPU_DOWN_PREPARE_FROZEN: