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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2020-11-02 20:43:10 +0100
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2020-11-11 02:39:40 +0100
commit28575c61ea602537a3d86fe301a53554e59452ae (patch)
treef7214b99b1dbe7c46f2b859b07452dc3f336f85c /kernel
parentftrace: Clean up the recursion code a bit (diff)
downloadlinux-28575c61ea602537a3d86fe301a53554e59452ae.tar.xz
linux-28575c61ea602537a3d86fe301a53554e59452ae.zip
ring-buffer: Add recording of ring buffer recursion into recursed_functions
Add a new config RING_BUFFER_RECORD_RECURSION that will place functions that recurse from the ring buffer into the ftrace recused_functions file. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/Kconfig14
-rw-r--r--kernel/trace/ring_buffer.c12
2 files changed, 25 insertions, 1 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 9b11c096d139..6aa36ec73ccb 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -752,6 +752,20 @@ config FTRACE_RECORD_RECURSION_SIZE
This file can be reset, but the limit can not change in
size at runtime.
+config RING_BUFFER_RECORD_RECURSION
+ bool "Record functions that recurse in the ring buffer"
+ depends on FTRACE_RECORD_RECURSION
+ # default y, because it is coupled with FTRACE_RECORD_RECURSION
+ default y
+ help
+ The ring buffer has its own internal recursion. Although when
+ recursion happens it wont cause harm because of the protection,
+ but it does cause an unwanted overhead. Enabling this option will
+ place where recursion was detected into the ftrace "recursed_functions"
+ file.
+
+ This will add more overhead to cases that have recursion.
+
config GCOV_PROFILE_FTRACE
bool "Enable GCOV profiling on ftrace subsystem"
depends on GCOV_KERNEL
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index dc83b3fa9fe7..ab68f28b8f4b 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -4,6 +4,7 @@
*
* Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
*/
+#include <linux/trace_recursion.h>
#include <linux/trace_events.h>
#include <linux/ring_buffer.h>
#include <linux/trace_clock.h>
@@ -3006,6 +3007,13 @@ rb_wakeups(struct trace_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer)
irq_work_queue(&cpu_buffer->irq_work.work);
}
+#ifdef CONFIG_RING_BUFFER_RECORD_RECURSION
+# define do_ring_buffer_record_recursion() \
+ do_ftrace_record_recursion(_THIS_IP_, _RET_IP_)
+#else
+# define do_ring_buffer_record_recursion() do { } while (0)
+#endif
+
/*
* The lock and unlock are done within a preempt disable section.
* The current_context per_cpu variable can only be modified
@@ -3088,8 +3096,10 @@ trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer)
* been updated yet. In this case, use the TRANSITION bit.
*/
bit = RB_CTX_TRANSITION;
- if (val & (1 << (bit + cpu_buffer->nest)))
+ if (val & (1 << (bit + cpu_buffer->nest))) {
+ do_ring_buffer_record_recursion();
return 1;
+ }
}
val |= (1 << (bit + cpu_buffer->nest));