From 06ca320952dc21c537055d2aa36a2c2e96a1b94d Mon Sep 17 00:00:00 2001 From: Yaowei Bai Date: Tue, 29 Sep 2015 22:43:31 +0800 Subject: ring-buffer: rb_is_reader_page() can return boolean Make rb_is_reader_page() return bool to improve readability due to this particular function only using either true or false as its return value. No functional change. Link: http://lkml.kernel.org/r/1443537816-5788-4-git-send-email-bywxiaobai@163.com Signed-off-by: Yaowei Bai Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index fc347f8b1bca..26a948f3187f 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -829,7 +829,7 @@ rb_is_head_page(struct ring_buffer_per_cpu *cpu_buffer, * writer is ever on it, the previous pointer never points * back to the reader page. */ -static int rb_is_reader_page(struct buffer_page *page) +static bool rb_is_reader_page(struct buffer_page *page) { struct list_head *list = page->list.prev; -- cgit v1.2.3 From 3d4e204d81eec30abffe55d01912e07ce81eef12 Mon Sep 17 00:00:00 2001 From: Yaowei Bai Date: Tue, 29 Sep 2015 22:43:32 +0800 Subject: ring_buffer: ring_buffer_empty{cpu}() can return boolean Make ring_buffer_empty() and ring_buffer_empty_cpu() return bool. No functional change. Link: http://lkml.kernel.org/r/1443537816-5788-5-git-send-email-bywxiaobai@163.com Signed-off-by: Yaowei Bai Signed-off-by: Steven Rostedt --- include/linux/ring_buffer.h | 4 ++-- kernel/trace/ring_buffer.c | 10 +++++----- 2 files changed, 7 insertions(+), 7 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index e2c13cd863bd..4acc552e9279 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -154,8 +154,8 @@ ring_buffer_swap_cpu(struct ring_buffer *buffer_a, } #endif -int ring_buffer_empty(struct ring_buffer *buffer); -int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu); +bool ring_buffer_empty(struct ring_buffer *buffer); +bool ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu); void ring_buffer_record_disable(struct ring_buffer *buffer); void ring_buffer_record_enable(struct ring_buffer *buffer); diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 26a948f3187f..fc9ce12666be 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4267,7 +4267,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_reset); * rind_buffer_empty - is the ring buffer empty? * @buffer: The ring buffer to test */ -int ring_buffer_empty(struct ring_buffer *buffer) +bool ring_buffer_empty(struct ring_buffer *buffer) { struct ring_buffer_per_cpu *cpu_buffer; unsigned long flags; @@ -4285,10 +4285,10 @@ int ring_buffer_empty(struct ring_buffer *buffer) local_irq_restore(flags); if (!ret) - return 0; + return false; } - return 1; + return true; } EXPORT_SYMBOL_GPL(ring_buffer_empty); @@ -4297,7 +4297,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_empty); * @buffer: The ring buffer * @cpu: The CPU buffer to test */ -int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) +bool ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; unsigned long flags; @@ -4305,7 +4305,7 @@ int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) int ret; if (!cpumask_test_cpu(cpu, buffer->cpumask)) - return 1; + return true; cpu_buffer = buffer->buffers[cpu]; local_irq_save(flags); -- cgit v1.2.3 From da58834cf2fa83fe3885753009fecaa49a85f246 Mon Sep 17 00:00:00 2001 From: Yaowei Bai Date: Tue, 29 Sep 2015 22:43:33 +0800 Subject: ring-buffer: rb_per_cpu_empty() can return boolean Makes rb_per_cpu_empty() return bool to improve readability. No functional change. Link: http://lkml.kernel.org/r/1443537816-5788-6-git-send-email-bywxiaobai@163.com Signed-off-by: Yaowei Bai Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index fc9ce12666be..a22878923a30 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -3039,7 +3039,7 @@ int ring_buffer_write(struct ring_buffer *buffer, } EXPORT_SYMBOL_GPL(ring_buffer_write); -static int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) +static bool rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) { struct buffer_page *reader = cpu_buffer->reader_page; struct buffer_page *head = rb_set_head_page(cpu_buffer); @@ -3047,7 +3047,7 @@ static int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) /* In case of error, head will be NULL */ if (unlikely(!head)) - return 1; + return true; return reader->read == rb_page_commit(reader) && (commit == reader || -- cgit v1.2.3 From cdb2a0a91566d413a6e4e2c57c5d341a2e1173f3 Mon Sep 17 00:00:00 2001 From: Yaowei Bai Date: Tue, 29 Sep 2015 22:43:34 +0800 Subject: ring-buffer: rb_event_is_commit() can return boolean Make rb_event_is_commit() return bool to improve readability due to this particular function only using either one or zero as its return value. No functional change. Link: http://lkml.kernel.org/r/1443537816-5788-7-git-send-email-bywxiaobai@163.com Signed-off-by: Yaowei Bai Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index a22878923a30..75f1d05ea82d 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2270,7 +2270,7 @@ rb_add_time_stamp(struct ring_buffer_event *event, u64 delta) return skip_time_extend(event); } -static inline int rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer, +static inline bool rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event); /** @@ -2498,7 +2498,7 @@ static inline void rb_event_discard(struct ring_buffer_event *event) event->time_delta = 1; } -static inline int +static inline bool rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event) { -- cgit v1.2.3 From b81f472a208d3e2b4392faa6d17037a89442f4ce Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Mon, 23 Nov 2015 10:35:36 -0500 Subject: ring-buffer: Update read stamp with first real commit on page Do not update the read stamp after swapping out the reader page from the write buffer. If the reader page is swapped out of the buffer before an event is written to it, then the read_stamp may get an out of date timestamp, as the page timestamp is updated on the first commit to that page. rb_get_reader_page() only returns a page if it has an event on it, otherwise it will return NULL. At that point, check if the page being returned has events and has not been read yet. Then at that point update the read_stamp to match the time stamp of the reader page. Cc: stable@vger.kernel.org # 2.6.30+ Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 75f1d05ea82d..4dd6d5bc4e11 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1887,12 +1887,6 @@ rb_event_index(struct ring_buffer_event *event) return (addr & ~PAGE_MASK) - BUF_PAGE_HDR_SIZE; } -static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer) -{ - cpu_buffer->read_stamp = cpu_buffer->reader_page->page->time_stamp; - cpu_buffer->reader_page->read = 0; -} - static void rb_inc_iter(struct ring_buffer_iter *iter) { struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; @@ -3626,7 +3620,7 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) /* Finally update the reader page to the new head */ cpu_buffer->reader_page = reader; - rb_reset_reader_page(cpu_buffer); + cpu_buffer->reader_page->read = 0; if (overwrite != cpu_buffer->last_overrun) { cpu_buffer->lost_events = overwrite - cpu_buffer->last_overrun; @@ -3636,6 +3630,10 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) goto again; out: + /* Update the read_stamp on the first event */ + if (reader && reader->read == 0) + cpu_buffer->read_stamp = reader->page->time_stamp; + arch_spin_unlock(&cpu_buffer->lock); local_irq_restore(flags); -- cgit v1.2.3 From bd1b7cd360f529394936f28746eb4aaa12d6770a Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Mon, 23 Nov 2015 17:35:24 -0500 Subject: ring-buffer: Put back the length if crossed page with add_timestamp Commit fcc742eaad7c "ring-buffer: Add event descriptor to simplify passing data" added a descriptor that holds various data instead of passing around several variables through parameters. The problem was that one of the parameters was modified in a function and the code was designed not to have an effect on that modified parameter. Now that the parameter is a descriptor and any modifications to it are non-volatile, the size of the data could be unnecessarily expanded. Remove the extra space added if a timestamp was added and the event went across the page. Cc: stable@vger.kernel.org # 4.3+ Fixes: fcc742eaad7c "ring-buffer: Add event descriptor to simplify passing data" Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'kernel/trace/ring_buffer.c') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 4dd6d5bc4e11..9c6045a27ba3 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2797,8 +2797,11 @@ rb_reserve_next_event(struct ring_buffer *buffer, event = __rb_reserve_next(cpu_buffer, &info); - if (unlikely(PTR_ERR(event) == -EAGAIN)) + if (unlikely(PTR_ERR(event) == -EAGAIN)) { + if (info.add_timestamp) + info.length -= RB_LEN_TIME_EXTEND; goto again; + } if (!event) goto out_fail; -- cgit v1.2.3