From d60da506cbeb3f1907a740547dd7ef04a93e908e Mon Sep 17 00:00:00 2001 From: Hiraku Toyooka Date: Wed, 17 Oct 2012 11:56:16 +0900 Subject: [PATCH 1/3] tracing: Add a resize function to make one buffer equivalent to another buffer Trace buffer size is now per-cpu, so that there are the following two patterns in resizing of buffers. (1) resize per-cpu buffers to same given size (2) resize per-cpu buffers to another trace_array's buffer size for each CPU (such as preparing the max_tr which is equivalent to the global_trace's size) __tracing_resize_ring_buffer() can be used for (1), and had implemented (2) inside it for resetting the global_trace to the original size. (2) was also implemented in another place. So this patch assembles them in a new function - resize_buffer_duplicate_size(). Link: http://lkml.kernel.org/r/20121017025616.2627.91226.stgit@falsita Signed-off-by: Hiraku Toyooka Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 58 +++++++++++++++++++++++--------------------- 1 file changed, 31 insertions(+), 27 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index b69cc380322..64ad9bc4275 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3034,6 +3034,31 @@ static void set_buffer_entries(struct trace_array *tr, unsigned long val) tr->data[cpu]->entries = val; } +/* resize @tr's buffer to the size of @size_tr's entries */ +static int resize_buffer_duplicate_size(struct trace_array *tr, + struct trace_array *size_tr, int cpu_id) +{ + int cpu, ret = 0; + + if (cpu_id == RING_BUFFER_ALL_CPUS) { + for_each_tracing_cpu(cpu) { + ret = ring_buffer_resize(tr->buffer, + size_tr->data[cpu]->entries, cpu); + if (ret < 0) + break; + tr->data[cpu]->entries = size_tr->data[cpu]->entries; + } + } else { + ret = ring_buffer_resize(tr->buffer, + size_tr->data[cpu_id]->entries, cpu_id); + if (ret == 0) + tr->data[cpu_id]->entries = + size_tr->data[cpu_id]->entries; + } + + return ret; +} + static int __tracing_resize_ring_buffer(unsigned long size, int cpu) { int ret; @@ -3058,23 +3083,8 @@ static int __tracing_resize_ring_buffer(unsigned long size, int cpu) ret = ring_buffer_resize(max_tr.buffer, size, cpu); if (ret < 0) { - int r = 0; - - if (cpu == RING_BUFFER_ALL_CPUS) { - int i; - for_each_tracing_cpu(i) { - r = ring_buffer_resize(global_trace.buffer, - global_trace.data[i]->entries, - i); - if (r < 0) - break; - } - } else { - r = ring_buffer_resize(global_trace.buffer, - global_trace.data[cpu]->entries, - cpu); - } - + int r = resize_buffer_duplicate_size(&global_trace, + &global_trace, cpu); if (r < 0) { /* * AARGH! We are left with different @@ -3212,17 +3222,11 @@ static int tracing_set_tracer(const char *buf) topts = create_trace_option_files(t); if (t->use_max_tr) { - int cpu; /* we need to make per cpu buffer sizes equivalent */ - for_each_tracing_cpu(cpu) { - ret = ring_buffer_resize(max_tr.buffer, - global_trace.data[cpu]->entries, - cpu); - if (ret < 0) - goto out; - max_tr.data[cpu]->entries = - global_trace.data[cpu]->entries; - } + ret = resize_buffer_duplicate_size(&max_tr, &global_trace, + RING_BUFFER_ALL_CPUS); + if (ret < 0) + goto out; } if (t->init) { From 717a9ef7f355480686cdbac3f32d6075437a923e Mon Sep 17 00:00:00 2001 From: Anton Vorontsov Date: Wed, 18 Jul 2012 11:56:01 -0700 Subject: [PATCH 2/3] tracing: Remove unneeded checks from the stack tracer It seems that 'ftrace_enabled' flag should not be used inside the tracer functions. The ftrace core is using this flag for internal purposes, and the flag wasn't meant to be used in tracers' runtime checks. stack tracer is the only tracer that abusing the flag. So stop it from serving as a bad example. Also, there is a local 'stack_trace_disabled' flag in the stack tracer, which is never updated; so it can be removed as well. Link: http://lkml.kernel.org/r/1342637761-9655-1-git-send-email-anton.vorontsov@linaro.org Signed-off-by: Anton Vorontsov Signed-off-by: Steven Rostedt --- kernel/trace/trace_stack.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index 0c1b165778e..42ca822fc70 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -33,7 +33,6 @@ static unsigned long max_stack_size; static arch_spinlock_t max_stack_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; -static int stack_trace_disabled __read_mostly; static DEFINE_PER_CPU(int, trace_active); static DEFINE_MUTEX(stack_sysctl_mutex); @@ -116,9 +115,6 @@ stack_trace_call(unsigned long ip, unsigned long parent_ip, { int cpu; - if (unlikely(!ftrace_enabled || stack_trace_disabled)) - return; - preempt_disable_notrace(); cpu = raw_smp_processor_id(); From bf3071f5a054db9e5bab873355d27a7330ce5187 Mon Sep 17 00:00:00 2001 From: Dave Jones Date: Wed, 25 Jul 2012 11:39:08 -0400 Subject: [PATCH 3/3] tracing: Remove unnecessary WARN_ONCE's from tracing_buffers_splice_read WARN shouldn't be used as a means of communicating failure to a userspace programmer. Link: http://lkml.kernel.org/r/20120725153908.GA25203@redhat.com Signed-off-by: Dave Jones Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 64ad9bc4275..5bc35907cc6 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4275,13 +4275,11 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, return -ENOMEM; if (*ppos & (PAGE_SIZE - 1)) { - WARN_ONCE(1, "Ftrace: previous read must page-align\n"); ret = -EINVAL; goto out; } if (len & (PAGE_SIZE - 1)) { - WARN_ONCE(1, "Ftrace: splice_read should page-align\n"); if (len < PAGE_SIZE) { ret = -EINVAL; goto out;