From d39cdd2036a63eef17a14efbd969405ca5612886 Mon Sep 17 00:00:00 2001 From: Chunyu Hu Date: Tue, 8 Mar 2016 21:37:01 +0800 Subject: tracing: Make tracer_flags use the right set_flag callback When I was updating the ftrace_stress test of ltp. I encountered a strange phenomemon, excute following steps: echo nop > /sys/kernel/debug/tracing/current_tracer echo 0 > /sys/kernel/debug/tracing/options/funcgraph-cpu bash: echo: write error: Invalid argument check dmesg: [ 1024.903855] nop_test_refuse flag set to 0: we refuse.Now cat trace_options to see the result The reason is that the trace option test will randomly setup trace option under tracing/options no matter what the current_tracer is. but the set_tracer_option is always using the set_flag callback from the current_tracer. This patch adds a pointer to tracer_flags and make it point to the tracer it belongs to. When the option is setup, the set_flag of the right tracer will be used no matter what the the current_tracer is. And the old dummy_tracer_flags is used for all the tracers which doesn't have a tracer_flags, having issue to use it to save the pointer of a tracer. So remove it and use dynamic dummy tracer_flags for tracers needing a dummy tracer_flags, as a result, there are no tracers sharing tracer_flags, so remove the check code. And save the current tracer to trace_option_dentry seems not good as it may waste mem space when mount the debug/trace fs more than one time. Link: http://lkml.kernel.org/r/1457444222-8654-1-git-send-email-chuhu@redhat.com Signed-off-by: Chunyu Hu [ Fixed up function tracer options to work with the change ] Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) (limited to 'kernel/trace/trace.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index d9293402ee68..b401a1892dc6 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -74,11 +74,6 @@ static struct tracer_opt dummy_tracer_opt[] = { { } }; -static struct tracer_flags dummy_tracer_flags = { - .val = 0, - .opts = dummy_tracer_opt -}; - static int dummy_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set) { @@ -1258,12 +1253,20 @@ int __init register_tracer(struct tracer *type) if (!type->set_flag) type->set_flag = &dummy_set_flag; - if (!type->flags) - type->flags = &dummy_tracer_flags; - else + if (!type->flags) { + /*allocate a dummy tracer_flags*/ + type->flags = kmalloc(sizeof(*type->flags), GFP_KERNEL); + if (!type->flags) + return -ENOMEM; + type->flags->val = 0; + type->flags->opts = dummy_tracer_opt; + } else if (!type->flags->opts) type->flags->opts = dummy_tracer_opt; + /* store the tracer for __set_tracer_option */ + type->flags->trace = type; + ret = run_tracer_selftest(type); if (ret < 0) goto out; @@ -3505,7 +3508,7 @@ static int __set_tracer_option(struct trace_array *tr, struct tracer_flags *tracer_flags, struct tracer_opt *opts, int neg) { - struct tracer *trace = tr->current_trace; + struct tracer *trace = tracer_flags->trace; int ret; ret = trace->set_flag(tr, tracer_flags->val, opts->bit, !neg); @@ -6391,11 +6394,8 @@ create_trace_option_files(struct trace_array *tr, struct tracer *tracer) return; for (i = 0; i < tr->nr_topts; i++) { - /* - * Check if these flags have already been added. - * Some tracers share flags. - */ - if (tr->topts[i].tracer->flags == tracer->flags) + /* Make sure there's no duplicate flags. */ + if (WARN_ON_ONCE(tr->topts[i].tracer->flags == tracer->flags)) return; } -- cgit v1.2.3-59-g8ed1b From c8ca003b2fde177b83de87f9f20f6a5933fb50bf Mon Sep 17 00:00:00 2001 From: Chunyu Hu Date: Mon, 14 Mar 2016 20:35:41 +0800 Subject: tracing: Fix return while holding a lock in register_tracer() commit d39cdd2036a6 ("tracing: Make tracer_flags use the right set_flag callback") introduces a potential mutex deadlock issue, as it forgets to free the mutex when allocaing the tracer_flags gets fail. The issue was found by Dan Carpenter through Smatch static code check tool. Link: http://lkml.kernel.org/r/1457958941-30265-1-git-send-email-chuhu@redhat.com Fixes: d39cdd2036a6 ("tracing: Make tracer_flags use the right set_flag callback") Reported-by: Dan Carpenter Signed-off-by: Chunyu Hu Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'kernel/trace/trace.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index b401a1892dc6..0ae46048f724 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1256,8 +1256,10 @@ int __init register_tracer(struct tracer *type) if (!type->flags) { /*allocate a dummy tracer_flags*/ type->flags = kmalloc(sizeof(*type->flags), GFP_KERNEL); - if (!type->flags) - return -ENOMEM; + if (!type->flags) { + ret = -ENOMEM; + goto out; + } type->flags->val = 0; type->flags->opts = dummy_tracer_opt; } else -- cgit v1.2.3-59-g8ed1b From a29054d9478d0435ab01b7544da4f674ab13f533 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Fri, 18 Mar 2016 15:46:48 -0400 Subject: tracing: Fix crash from reading trace_pipe with sendfile If tracing contains data and the trace_pipe file is read with sendfile(), then it can trigger a NULL pointer dereference and various BUG_ON within the VM code. There's a patch to fix this in the splice_to_pipe() code, but it's also a good idea to not let that happen from trace_pipe either. Link: http://lkml.kernel.org/r/1457641146-9068-1-git-send-email-rabin@rab.in Cc: stable@vger.kernel.org # 2.6.30+ Reported-by: Rabin Vincent Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'kernel/trace/trace.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 0ae46048f724..cb2b708e4ea7 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4954,7 +4954,10 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, spd.nr_pages = i; - ret = splice_to_pipe(pipe, &spd); + if (i) + ret = splice_to_pipe(pipe, &spd); + else + ret = 0; out: splice_shrink_spd(&spd); return ret; -- cgit v1.2.3-59-g8ed1b From 7e6867bf831c71fe0e47438831ae3a94d4c7ab3c Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 18 Mar 2016 16:28:04 +0100 Subject: tracing: Record and show NMI state The latency tracer format has a nice column to indicate IRQ state, but this is not able to tell us about NMI state. When tracing perf interrupt handlers (which often run in NMI context) it is very useful to see how the events nest. Link: http://lkml.kernel.org/r/20160318153022.105068893@infradead.org Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 1 + kernel/trace/trace.h | 1 + kernel/trace/trace_output.c | 10 +++++++--- 3 files changed, 9 insertions(+), 3 deletions(-) (limited to 'kernel/trace/trace.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index cb2b708e4ea7..7bdf8ba323ec 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1664,6 +1664,7 @@ tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags, #else TRACE_FLAG_IRQS_NOSUPPORT | #endif + ((pc & NMI_MASK ) ? TRACE_FLAG_NMI : 0) | ((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) | ((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) | (tif_need_resched() ? TRACE_FLAG_NEED_RESCHED : 0) | diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 39588c23dd8b..3fff4adfd431 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -125,6 +125,7 @@ enum trace_flag_type { TRACE_FLAG_HARDIRQ = 0x08, TRACE_FLAG_SOFTIRQ = 0x10, TRACE_FLAG_PREEMPT_RESCHED = 0x20, + TRACE_FLAG_NMI = 0x40, }; #define TRACE_BUF_SIZE 1024 diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index 282982195e09..0bb9cf2d53e6 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -389,7 +389,9 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry) char irqs_off; int hardirq; int softirq; + int nmi; + nmi = entry->flags & TRACE_FLAG_NMI; hardirq = entry->flags & TRACE_FLAG_HARDIRQ; softirq = entry->flags & TRACE_FLAG_SOFTIRQ; @@ -415,10 +417,12 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry) } hardsoft_irq = + (nmi && hardirq) ? 'Z' : + nmi ? 'z' : (hardirq && softirq) ? 'H' : - hardirq ? 'h' : - softirq ? 's' : - '.'; + hardirq ? 'h' : + softirq ? 's' : + '.' ; trace_seq_printf(s, "%c%c%c", irqs_off, need_resched, hardsoft_irq); -- cgit v1.2.3-59-g8ed1b