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author | Steven Rostedt (Red Hat) <rostedt@goodmis.org> | 2015-05-28 13:21:34 -0400 |
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committer | Steven Rostedt <rostedt@goodmis.org> | 2015-05-28 16:47:39 -0400 |
commit | 3c6296f716ebef704b76070d90567ab4faa8462c (patch) | |
tree | fc9a587239395d5dc882c8f17756ba6aa29ba838 | |
parent | 289a5a25c5d0949e4d9b9ca4f334b6af5a83e090 (diff) | |
download | linux-stable-3c6296f716ebef704b76070d90567ab4faa8462c.tar.gz linux-stable-3c6296f716ebef704b76070d90567ab4faa8462c.tar.bz2 linux-stable-3c6296f716ebef704b76070d90567ab4faa8462c.zip |
ring-buffer: Remove useless unused tracing_off_permanent()
The tracing_off_permanent() call is a way to disable all ring_buffers.
Nothing uses it and nothing should use it, as tracing_off() and
friends are better, as they disable the ring buffers related to
tracing. The tracing_off_permanent() even disabled non tracing
ring buffers. This is a bit drastic, and was added to handle NMIs
doing outputs that could corrupt the ring buffer when only tracing
used them. It is now obsolete and adds a little overhead, it should
be removed.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r-- | include/linux/kernel.h | 6 | ||||
-rw-r--r-- | kernel/trace/ring_buffer.c | 61 |
2 files changed, 0 insertions, 67 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 3a5b48e52a9e..d948718a83d7 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -532,12 +532,6 @@ bool mac_pton(const char *s, u8 *mac); * * Most likely, you want to use tracing_on/tracing_off. */ -#ifdef CONFIG_RING_BUFFER -/* trace_off_permanent stops recording with no way to bring it back */ -void tracing_off_permanent(void); -#else -static inline void tracing_off_permanent(void) { } -#endif enum ftrace_dump_mode { DUMP_NONE, diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index e9420fdc7409..0fc5add6423b 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -115,63 +115,11 @@ int ring_buffer_print_entry_header(struct trace_seq *s) * */ -/* - * A fast way to enable or disable all ring buffers is to - * call tracing_on or tracing_off. Turning off the ring buffers - * prevents all ring buffers from being recorded to. - * Turning this switch on, makes it OK to write to the - * ring buffer, if the ring buffer is enabled itself. - * - * There's three layers that must be on in order to write - * to the ring buffer. - * - * 1) This global flag must be set. - * 2) The ring buffer must be enabled for recording. - * 3) The per cpu buffer must be enabled for recording. - * - * In case of an anomaly, this global flag has a bit set that - * will permantly disable all ring buffers. - */ - -/* - * Global flag to disable all recording to ring buffers - * This has two bits: ON, DISABLED - * - * ON DISABLED - * ---- ---------- - * 0 0 : ring buffers are off - * 1 0 : ring buffers are on - * X 1 : ring buffers are permanently disabled - */ - -enum { - RB_BUFFERS_ON_BIT = 0, - RB_BUFFERS_DISABLED_BIT = 1, -}; - -enum { - RB_BUFFERS_ON = 1 << RB_BUFFERS_ON_BIT, - RB_BUFFERS_DISABLED = 1 << RB_BUFFERS_DISABLED_BIT, -}; - -static unsigned long ring_buffer_flags __read_mostly = RB_BUFFERS_ON; - /* Used for individual buffers (after the counter) */ #define RB_BUFFER_OFF (1 << 20) #define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) -/** - * tracing_off_permanent - permanently disable ring buffers - * - * This function, once called, will disable all ring buffers - * permanently. - */ -void tracing_off_permanent(void) -{ - set_bit(RB_BUFFERS_DISABLED_BIT, &ring_buffer_flags); -} - #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) @@ -2728,9 +2676,6 @@ ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length) struct ring_buffer_event *event; int cpu; - if (ring_buffer_flags != RB_BUFFERS_ON) - return NULL; - /* If we are tracing schedule, we don't want to recurse */ preempt_disable_notrace(); @@ -2992,9 +2937,6 @@ int ring_buffer_write(struct ring_buffer *buffer, int ret = -EBUSY; int cpu; - if (ring_buffer_flags != RB_BUFFERS_ON) - return -EBUSY; - preempt_disable_notrace(); if (atomic_read(&buffer->record_disabled)) @@ -4350,9 +4292,6 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, ret = -EAGAIN; - if (ring_buffer_flags != RB_BUFFERS_ON) - goto out; - if (atomic_read(&buffer_a->record_disabled)) goto out; |