diff options
Diffstat (limited to 'kernel/trace/ring_buffer.c')
| -rw-r--r-- | kernel/trace/ring_buffer.c | 764 |
1 files changed, 402 insertions, 362 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 6260717c1..fc347f8b1 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -400,6 +400,17 @@ struct rb_irq_work { }; /* + * Structure to hold event state and handle nested events. + */ +struct rb_event_info { + u64 ts; + u64 delta; + unsigned long length; + struct buffer_page *tail_page; + int add_timestamp; +}; + +/* * Used for which event context the event is in. * NMI = 0 * IRQ = 1 @@ -1876,73 +1887,6 @@ rb_event_index(struct ring_buffer_event *event) return (addr & ~PAGE_MASK) - BUF_PAGE_HDR_SIZE; } -static inline int -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; - - index = rb_event_index(event); - addr &= PAGE_MASK; - - return cpu_buffer->commit_page->page == (void *)addr && - rb_commit_index(cpu_buffer) == index; -} - -static void -rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) -{ - unsigned long max_count; - - /* - * We only race with interrupts and NMIs on this CPU. - * If we own the commit event, then we can commit - * all others that interrupted us, since the interruptions - * are in stack format (they finish before they come - * back to us). This allows us to do a simple loop to - * assign the commit to the tail. - */ - again: - max_count = cpu_buffer->nr_pages * 100; - - while (cpu_buffer->commit_page != cpu_buffer->tail_page) { - if (RB_WARN_ON(cpu_buffer, !(--max_count))) - return; - if (RB_WARN_ON(cpu_buffer, - rb_is_reader_page(cpu_buffer->tail_page))) - return; - local_set(&cpu_buffer->commit_page->page->commit, - rb_page_write(cpu_buffer->commit_page)); - rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); - cpu_buffer->write_stamp = - cpu_buffer->commit_page->page->time_stamp; - /* add barrier to keep gcc from optimizing too much */ - barrier(); - } - while (rb_commit_index(cpu_buffer) != - rb_page_write(cpu_buffer->commit_page)) { - - local_set(&cpu_buffer->commit_page->page->commit, - rb_page_write(cpu_buffer->commit_page)); - RB_WARN_ON(cpu_buffer, - local_read(&cpu_buffer->commit_page->page->commit) & - ~RB_WRITE_MASK); - barrier(); - } - - /* again, keep gcc from optimizing */ - barrier(); - - /* - * If an interrupt came in just after the first while loop - * and pushed the tail page forward, we will be left with - * a dangling commit that will never go forward. - */ - if (unlikely(cpu_buffer->commit_page != cpu_buffer->tail_page)) - goto again; -} - static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer) { cpu_buffer->read_stamp = cpu_buffer->reader_page->page->time_stamp; @@ -1968,64 +1912,6 @@ static void rb_inc_iter(struct ring_buffer_iter *iter) iter->head = 0; } -/* Slow path, do not inline */ -static noinline struct ring_buffer_event * -rb_add_time_stamp(struct ring_buffer_event *event, u64 delta) -{ - event->type_len = RINGBUF_TYPE_TIME_EXTEND; - - /* Not the first event on the page? */ - if (rb_event_index(event)) { - event->time_delta = delta & TS_MASK; - event->array[0] = delta >> TS_SHIFT; - } else { - /* nope, just zero it */ - event->time_delta = 0; - event->array[0] = 0; - } - - return skip_time_extend(event); -} - -/** - * rb_update_event - update event type and data - * @event: the event to update - * @type: the type of event - * @length: the size of the event field in the ring buffer - * - * Update the type and data fields of the event. The length - * is the actual size that is written to the ring buffer, - * and with this, we can determine what to place into the - * data field. - */ -static void -rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, - struct ring_buffer_event *event, unsigned length, - int add_timestamp, u64 delta) -{ - /* Only a commit updates the timestamp */ - if (unlikely(!rb_event_is_commit(cpu_buffer, event))) - delta = 0; - - /* - * If we need to add a timestamp, then we - * add it to the start of the resevered space. - */ - if (unlikely(add_timestamp)) { - event = rb_add_time_stamp(event, delta); - length -= RB_LEN_TIME_EXTEND; - delta = 0; - } - - event->time_delta = delta; - length -= RB_EVNT_HDR_SIZE; - if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) { - event->type_len = 0; - event->array[0] = length; - } else - event->type_len = DIV_ROUND_UP(length, RB_ALIGNMENT); -} - /* * rb_handle_head_page - writer hit the head page * @@ -2184,29 +2070,13 @@ rb_handle_head_page(struct ring_buffer_per_cpu *cpu_buffer, return 0; } -static unsigned rb_calculate_event_length(unsigned length) -{ - struct ring_buffer_event event; /* Used only for sizeof array */ - - /* zero length can cause confusions */ - if (!length) - length++; - - if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) - length += sizeof(event.array[0]); - - length += RB_EVNT_HDR_SIZE; - length = ALIGN(length, RB_ARCH_ALIGNMENT); - - 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) + unsigned long tail, struct rb_event_info *info) { + struct buffer_page *tail_page = info->tail_page; struct ring_buffer_event *event; + unsigned long length = info->length; /* * Only the event that crossed the page boundary @@ -2276,13 +2146,14 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, */ static noinline struct ring_buffer_event * rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, - unsigned long length, unsigned long tail, - struct buffer_page *tail_page, u64 ts) + unsigned long tail, struct rb_event_info *info) { + struct buffer_page *tail_page = info->tail_page; struct buffer_page *commit_page = cpu_buffer->commit_page; struct ring_buffer *buffer = cpu_buffer->buffer; struct buffer_page *next_page; int ret; + u64 ts; next_page = tail_page; @@ -2368,74 +2239,120 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, out_again: - rb_reset_tail(cpu_buffer, tail_page, tail, length); + rb_reset_tail(cpu_buffer, tail, info); /* fail and let the caller try again */ return ERR_PTR(-EAGAIN); out_reset: /* reset write */ - rb_reset_tail(cpu_buffer, tail_page, tail, length); + rb_reset_tail(cpu_buffer, tail, info); return NULL; } -static struct ring_buffer_event * -__rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, - unsigned long length, u64 ts, - u64 delta, int add_timestamp) +/* Slow path, do not inline */ +static noinline struct ring_buffer_event * +rb_add_time_stamp(struct ring_buffer_event *event, u64 delta) { - struct buffer_page *tail_page; - struct ring_buffer_event *event; - unsigned long tail, write; + event->type_len = RINGBUF_TYPE_TIME_EXTEND; - /* - * If the time delta since the last event is too big to - * hold in the time field of the event, then we append a - * TIME EXTEND event ahead of the data event. - */ - if (unlikely(add_timestamp)) - length += RB_LEN_TIME_EXTEND; + /* Not the first event on the page? */ + if (rb_event_index(event)) { + event->time_delta = delta & TS_MASK; + event->array[0] = delta >> TS_SHIFT; + } else { + /* nope, just zero it */ + event->time_delta = 0; + event->array[0] = 0; + } - tail_page = cpu_buffer->tail_page; - write = local_add_return(length, &tail_page->write); + return skip_time_extend(event); +} - /* set write to only the index of the write */ - write &= RB_WRITE_MASK; - tail = write - length; +static inline int rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer, + struct ring_buffer_event *event); + +/** + * rb_update_event - update event type and data + * @event: the event to update + * @type: the type of event + * @length: the size of the event field in the ring buffer + * + * Update the type and data fields of the event. The length + * is the actual size that is written to the ring buffer, + * and with this, we can determine what to place into the + * data field. + */ +static void +rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, + struct ring_buffer_event *event, + struct rb_event_info *info) +{ + unsigned length = info->length; + u64 delta = info->delta; + + /* Only a commit updates the timestamp */ + if (unlikely(!rb_event_is_commit(cpu_buffer, event))) + delta = 0; /* - * If this is the first commit on the page, then it has the same - * timestamp as the page itself. + * If we need to add a timestamp, then we + * add it to the start of the resevered space. */ - if (!tail) + if (unlikely(info->add_timestamp)) { + event = rb_add_time_stamp(event, delta); + length -= RB_LEN_TIME_EXTEND; delta = 0; + } - /* See if we shot pass the end of this buffer page */ - if (unlikely(write > BUF_PAGE_SIZE)) - return rb_move_tail(cpu_buffer, length, tail, - tail_page, ts); + event->time_delta = delta; + length -= RB_EVNT_HDR_SIZE; + if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) { + event->type_len = 0; + event->array[0] = length; + } else + event->type_len = DIV_ROUND_UP(length, RB_ALIGNMENT); +} - /* We reserved something on the buffer */ +static unsigned rb_calculate_event_length(unsigned length) +{ + struct ring_buffer_event event; /* Used only for sizeof array */ - event = __rb_page_index(tail_page, tail); - kmemcheck_annotate_bitfield(event, bitfield); - rb_update_event(cpu_buffer, event, length, add_timestamp, delta); + /* zero length can cause confusions */ + if (!length) + length++; - local_inc(&tail_page->entries); + if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) + length += sizeof(event.array[0]); + + length += RB_EVNT_HDR_SIZE; + length = ALIGN(length, RB_ARCH_ALIGNMENT); /* - * If this is the first commit on the page, then update - * its timestamp. + * In case the time delta is larger than the 27 bits for it + * in the header, we need to add a timestamp. If another + * event comes in when trying to discard this one to increase + * the length, then the timestamp will be added in the allocated + * space of this event. If length is bigger than the size needed + * for the TIME_EXTEND, then padding has to be used. The events + * length must be either RB_LEN_TIME_EXTEND, or greater than or equal + * to RB_LEN_TIME_EXTEND + 8, as 8 is the minimum size for padding. + * As length is a multiple of 4, we only need to worry if it + * is 12 (RB_LEN_TIME_EXTEND + 4). */ - if (!tail) - tail_page->page->time_stamp = ts; + if (length == RB_LEN_TIME_EXTEND + RB_ALIGNMENT) + length += RB_ALIGNMENT; - /* account for these added bytes */ - local_add(length, &cpu_buffer->entries_bytes); + return length; +} - return event; +#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK +static inline bool sched_clock_stable(void) +{ + return true; } +#endif static inline int rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, @@ -2483,6 +2400,59 @@ static void rb_start_commit(struct ring_buffer_per_cpu *cpu_buffer) local_inc(&cpu_buffer->commits); } +static void +rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) +{ + unsigned long max_count; + + /* + * We only race with interrupts and NMIs on this CPU. + * If we own the commit event, then we can commit + * all others that interrupted us, since the interruptions + * are in stack format (they finish before they come + * back to us). This allows us to do a simple loop to + * assign the commit to the tail. + */ + again: + max_count = cpu_buffer->nr_pages * 100; + + while (cpu_buffer->commit_page != cpu_buffer->tail_page) { + if (RB_WARN_ON(cpu_buffer, !(--max_count))) + return; + if (RB_WARN_ON(cpu_buffer, + rb_is_reader_page(cpu_buffer->tail_page))) + return; + local_set(&cpu_buffer->commit_page->page->commit, + rb_page_write(cpu_buffer->commit_page)); + rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); + cpu_buffer->write_stamp = + cpu_buffer->commit_page->page->time_stamp; + /* add barrier to keep gcc from optimizing too much */ + barrier(); + } + while (rb_commit_index(cpu_buffer) != + rb_page_write(cpu_buffer->commit_page)) { + + local_set(&cpu_buffer->commit_page->page->commit, + rb_page_write(cpu_buffer->commit_page)); + RB_WARN_ON(cpu_buffer, + local_read(&cpu_buffer->commit_page->page->commit) & + ~RB_WRITE_MASK); + barrier(); + } + + /* again, keep gcc from optimizing */ + barrier(); + + /* + * If an interrupt came in just after the first while loop + * and pushed the tail page forward, we will be left with + * a dangling commit that will never go forward. + */ + if (unlikely(cpu_buffer->commit_page != cpu_buffer->tail_page)) + goto again; +} + static inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer) { unsigned long commits; @@ -2515,91 +2485,94 @@ static inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer) } } -static struct ring_buffer_event * -rb_reserve_next_event(struct ring_buffer *buffer, - struct ring_buffer_per_cpu *cpu_buffer, - unsigned long length) +static inline void rb_event_discard(struct ring_buffer_event *event) { - struct ring_buffer_event *event; - u64 ts, delta; - int nr_loops = 0; - int add_timestamp; - u64 diff; + if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) + event = skip_time_extend(event); - rb_start_commit(cpu_buffer); + /* array[0] holds the actual length for the discarded event */ + event->array[0] = rb_event_data_length(event) - RB_EVNT_HDR_SIZE; + event->type_len = RINGBUF_TYPE_PADDING; + /* time delta must be non zero */ + if (!event->time_delta) + event->time_delta = 1; +} -#ifdef CONFIG_RING_BUFFER_ALLOW_SWAP - /* - * Due to the ability to swap a cpu buffer from a buffer - * it is possible it was swapped before we committed. - * (committing stops a swap). We check for it here and - * if it happened, we have to fail the write. - */ - barrier(); - if (unlikely(ACCESS_ONCE(cpu_buffer->buffer) != buffer)) { - local_dec(&cpu_buffer->committing); - local_dec(&cpu_buffer->commits); - return NULL; - } -#endif +static inline int +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; - length = rb_calculate_event_length(length); - again: - add_timestamp = 0; - delta = 0; + index = rb_event_index(event); + addr &= PAGE_MASK; + + return cpu_buffer->commit_page->page == (void *)addr && + rb_commit_index(cpu_buffer) == index; +} + +static void +rb_update_write_stamp(struct ring_buffer_per_cpu *cpu_buffer, + struct ring_buffer_event *event) +{ + u64 delta; /* - * We allow for interrupts to reenter here and do a trace. - * If one does, it will cause this original code to loop - * back here. Even with heavy interrupts happening, this - * should only happen a few times in a row. If this happens - * 1000 times in a row, there must be either an interrupt - * storm or we have something buggy. - * Bail! + * The event first in the commit queue updates the + * time stamp. */ - if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) - goto out_fail; + if (rb_event_is_commit(cpu_buffer, event)) { + /* + * A commit event that is first on a page + * updates the write timestamp with the page stamp + */ + if (!rb_event_index(event)) + cpu_buffer->write_stamp = + cpu_buffer->commit_page->page->time_stamp; + else if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { + delta = event->array[0]; + delta <<= TS_SHIFT; + delta += event->time_delta; + cpu_buffer->write_stamp += delta; + } else + cpu_buffer->write_stamp += event->time_delta; + } +} - ts = rb_time_stamp(cpu_buffer->buffer); - diff = ts - cpu_buffer->write_stamp; +static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, + struct ring_buffer_event *event) +{ + local_inc(&cpu_buffer->entries); + rb_update_write_stamp(cpu_buffer, event); + rb_end_commit(cpu_buffer); +} - /* make sure this diff is calculated here */ - barrier(); +static __always_inline void +rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer) +{ + bool pagebusy; - /* Did the write stamp get updated already? */ - if (likely(ts >= cpu_buffer->write_stamp)) { - delta = diff; - if (unlikely(test_time_stamp(delta))) { - int local_clock_stable = 1; -#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK - local_clock_stable = sched_clock_stable(); -#endif - WARN_ONCE(delta > (1ULL << 59), - KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s", - (unsigned long long)delta, - (unsigned long long)ts, - (unsigned long long)cpu_buffer->write_stamp, - local_clock_stable ? "" : - "If you just came from a suspend/resume,\n" - "please switch to the trace global clock:\n" - " echo global > /sys/kernel/debug/tracing/trace_clock\n"); - add_timestamp = 1; - } + if (buffer->irq_work.waiters_pending) { + buffer->irq_work.waiters_pending = false; + /* irq_work_queue() supplies it's own memory barriers */ + irq_work_queue(&buffer->irq_work.work); } - event = __rb_reserve_next(cpu_buffer, length, ts, - delta, add_timestamp); - if (unlikely(PTR_ERR(event) == -EAGAIN)) - goto again; - - if (!event) - goto out_fail; + if (cpu_buffer->irq_work.waiters_pending) { + cpu_buffer->irq_work.waiters_pending = false; + /* irq_work_queue() supplies it's own memory barriers */ + irq_work_queue(&cpu_buffer->irq_work.work); + } - return event; + pagebusy = cpu_buffer->reader_page == cpu_buffer->commit_page; - out_fail: - rb_end_commit(cpu_buffer); - return NULL; + if (!pagebusy && cpu_buffer->irq_work.full_waiters_pending) { + cpu_buffer->irq_work.wakeup_full = true; + cpu_buffer->irq_work.full_waiters_pending = false; + /* irq_work_queue() supplies it's own memory barriers */ + irq_work_queue(&cpu_buffer->irq_work.work); + } } /* @@ -2672,6 +2645,178 @@ trace_recursive_unlock(struct ring_buffer_per_cpu *cpu_buffer) } /** + * ring_buffer_unlock_commit - commit a reserved + * @buffer: The buffer to commit to + * @event: The event pointer to commit. + * + * This commits the data to the ring buffer, and releases any locks held. + * + * Must be paired with ring_buffer_lock_reserve. + */ +int ring_buffer_unlock_commit(struct ring_buffer *buffer, + struct ring_buffer_event *event) +{ + struct ring_buffer_per_cpu *cpu_buffer; + int cpu = raw_smp_processor_id(); + + cpu_buffer = buffer->buffers[cpu]; + + rb_commit(cpu_buffer, event); + + rb_wakeups(buffer, cpu_buffer); + + trace_recursive_unlock(cpu_buffer); + + preempt_enable_notrace(); + + return 0; +} +EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); + +static noinline void +rb_handle_timestamp(struct ring_buffer_per_cpu *cpu_buffer, + struct rb_event_info *info) +{ + WARN_ONCE(info->delta > (1ULL << 59), + KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s", + (unsigned long long)info->delta, + (unsigned long long)info->ts, + (unsigned long long)cpu_buffer->write_stamp, + sched_clock_stable() ? "" : + "If you just came from a suspend/resume,\n" + "please switch to the trace global clock:\n" + " echo global > /sys/kernel/debug/tracing/trace_clock\n"); + info->add_timestamp = 1; +} + +static struct ring_buffer_event * +__rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, + struct rb_event_info *info) +{ + struct ring_buffer_event *event; + struct buffer_page *tail_page; + unsigned long tail, write; + + /* + * If the time delta since the last event is too big to + * hold in the time field of the event, then we append a + * TIME EXTEND event ahead of the data event. + */ + if (unlikely(info->add_timestamp)) + info->length += RB_LEN_TIME_EXTEND; + + tail_page = info->tail_page = cpu_buffer->tail_page; + write = local_add_return(info->length, &tail_page->write); + + /* set write to only the index of the write */ + write &= RB_WRITE_MASK; + tail = write - info->length; + + /* + * If this is the first commit on the page, then it has the same + * timestamp as the page itself. + */ + if (!tail) + info->delta = 0; + + /* See if we shot pass the end of this buffer page */ + if (unlikely(write > BUF_PAGE_SIZE)) + return rb_move_tail(cpu_buffer, tail, info); + + /* We reserved something on the buffer */ + + event = __rb_page_index(tail_page, tail); + kmemcheck_annotate_bitfield(event, bitfield); + rb_update_event(cpu_buffer, event, info); + + local_inc(&tail_page->entries); + + /* + * If this is the first commit on the page, then update + * its timestamp. + */ + if (!tail) + tail_page->page->time_stamp = info->ts; + + /* account for these added bytes */ + local_add(info->length, &cpu_buffer->entries_bytes); + + return event; +} + +static struct ring_buffer_event * +rb_reserve_next_event(struct ring_buffer *buffer, + struct ring_buffer_per_cpu *cpu_buffer, + unsigned long length) +{ + struct ring_buffer_event *event; + struct rb_event_info info; + int nr_loops = 0; + u64 diff; + + rb_start_commit(cpu_buffer); + +#ifdef CONFIG_RING_BUFFER_ALLOW_SWAP + /* + * Due to the ability to swap a cpu buffer from a buffer + * it is possible it was swapped before we committed. + * (committing stops a swap). We check for it here and + * if it happened, we have to fail the write. + */ + barrier(); + if (unlikely(ACCESS_ONCE(cpu_buffer->buffer) != buffer)) { + local_dec(&cpu_buffer->committing); + local_dec(&cpu_buffer->commits); + return NULL; + } +#endif + + info.length = rb_calculate_event_length(length); + again: + info.add_timestamp = 0; + info.delta = 0; + + /* + * We allow for interrupts to reenter here and do a trace. + * If one does, it will cause this original code to loop + * back here. Even with heavy interrupts happening, this + * should only happen a few times in a row. If this happens + * 1000 times in a row, there must be either an interrupt + * storm or we have something buggy. + * Bail! + */ + if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) + goto out_fail; + + info.ts = rb_time_stamp(cpu_buffer->buffer); + diff = info.ts - cpu_buffer->write_stamp; + + /* make sure this diff is calculated here */ + barrier(); + + /* Did the write stamp get updated already? */ + if (likely(info.ts >= cpu_buffer->write_stamp)) { + info.delta = diff; + if (unlikely(test_time_stamp(info.delta))) + rb_handle_timestamp(cpu_buffer, &info); + } + + event = __rb_reserve_next(cpu_buffer, &info); + + if (unlikely(PTR_ERR(event) == -EAGAIN)) + goto again; + + if (!event) + goto out_fail; + + return event; + + out_fail: + rb_end_commit(cpu_buffer); + return NULL; +} + +/** * ring_buffer_lock_reserve - reserve a part of the buffer * @buffer: the ring buffer to reserve from * @length: the length of the data to reserve (excluding event header) @@ -2729,111 +2874,6 @@ ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length) } EXPORT_SYMBOL_GPL(ring_buffer_lock_reserve); -static void -rb_update_write_stamp(struct ring_buffer_per_cpu *cpu_buffer, - struct ring_buffer_event *event) -{ - u64 delta; - - /* - * The event first in the commit queue updates the - * time stamp. - */ - if (rb_event_is_commit(cpu_buffer, event)) { - /* - * A commit event that is first on a page - * updates the write timestamp with the page stamp - */ - if (!rb_event_index(event)) - cpu_buffer->write_stamp = - cpu_buffer->commit_page->page->time_stamp; - else if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { - delta = event->array[0]; - delta <<= TS_SHIFT; - delta += event->time_delta; - cpu_buffer->write_stamp += delta; - } else - cpu_buffer->write_stamp += event->time_delta; - } -} - -static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, - struct ring_buffer_event *event) -{ - local_inc(&cpu_buffer->entries); - rb_update_write_stamp(cpu_buffer, event); - rb_end_commit(cpu_buffer); -} - -static __always_inline void -rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer) -{ - bool pagebusy; - - if (buffer->irq_work.waiters_pending) { - buffer->irq_work.waiters_pending = false; - /* irq_work_queue() supplies it's own memory barriers */ - irq_work_queue(&buffer->irq_work.work); - } - - if (cpu_buffer->irq_work.waiters_pending) { - cpu_buffer->irq_work.waiters_pending = false; - /* irq_work_queue() supplies it's own memory barriers */ - irq_work_queue(&cpu_buffer->irq_work.work); - } - - pagebusy = cpu_buffer->reader_page == cpu_buffer->commit_page; - - if (!pagebusy && cpu_buffer->irq_work.full_waiters_pending) { - cpu_buffer->irq_work.wakeup_full = true; - cpu_buffer->irq_work.full_waiters_pending = false; - /* irq_work_queue() supplies it's own memory barriers */ - irq_work_queue(&cpu_buffer->irq_work.work); - } -} - -/** - * ring_buffer_unlock_commit - commit a reserved - * @buffer: The buffer to commit to - * @event: The event pointer to commit. - * - * This commits the data to the ring buffer, and releases any locks held. - * - * Must be paired with ring_buffer_lock_reserve. - */ -int ring_buffer_unlock_commit(struct ring_buffer *buffer, - struct ring_buffer_event *event) -{ - struct ring_buffer_per_cpu *cpu_buffer; - int cpu = raw_smp_processor_id(); - - cpu_buffer = buffer->buffers[cpu]; - - rb_commit(cpu_buffer, event); - - rb_wakeups(buffer, cpu_buffer); - - trace_recursive_unlock(cpu_buffer); - - preempt_enable_notrace(); - - return 0; -} -EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); - -static inline void rb_event_discard(struct ring_buffer_event *event) -{ - if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) - event = skip_time_extend(event); - - /* array[0] holds the actual length for the discarded event */ - event->array[0] = rb_event_data_length(event) - RB_EVNT_HDR_SIZE; - event->type_len = RINGBUF_TYPE_PADDING; - /* time delta must be non zero */ - if (!event->time_delta) - event->time_delta = 1; -} - /* * Decrement the entries to the page that an event is on. * The event does not even need to exist, only the pointer |