From: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Add a simple way to export per cpu counters in debugfs.
This is done using a section, so that they can be declared using
a simple macro with minimal typing.
OPEN: modules are not supported yet.
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
---
fs/debugfs/Makefile | 2 +-
fs/debugfs/counter.c | 73 +++++++++++++++++++++++++++++++++++++
include/asm-generic/vmlinux.lds.h | 6 +++
include/linux/debugfs.h | 27 ++++++++++++++
4 files changed, 107 insertions(+), 1 deletions(-)
create mode 100644 fs/debugfs/counter.c
diff --git a/fs/debugfs/Makefile b/fs/debugfs/Makefile
index 840c456..21be8d3 100644
--- a/fs/debugfs/Makefile
+++ b/fs/debugfs/Makefile
@@ -1,4 +1,4 @@
-debugfs-objs := inode.o file.o
+debugfs-objs := inode.o file.o counter.o
obj-$(CONFIG_DEBUG_FS) += debugfs.o
diff --git a/fs/debugfs/counter.c b/fs/debugfs/counter.c
new file mode 100644
index 0000000..2372faf
--- /dev/null
+++ b/fs/debugfs/counter.c
@@ -0,0 +1,73 @@
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/percpu.h>
+#include <linux/kernel.h>
+
+/* OPEN: implement module support */
+
+extern struct debugfs_counter __start___debugfs[], __stop___debugfs[];
+
+static unsigned sum_counter(unsigned __percpu *counter)
+{
+ int cpu;
+ unsigned sum = 0;
+
+ for_each_online_cpu (cpu)
+ sum += per_cpu(*counter, cpu);
+ return sum;
+}
+
+static int
+dump_counters(struct seq_file *m,
+ struct debugfs_counter *cnt, struct debugfs_counter *stop,
+ char *fn)
+{
+ int n = 0;
+ for (; cnt < stop; cnt++)
+ if (fn[0] == cnt->fn[0] && !strcmp(cnt->fn, fn))
+ n += seq_printf(m, "%s: %u\n",
+ cnt->name, sum_counter(cnt->ptr));
+ return n;
+}
+
+static int show_debugfs_counter(struct seq_file *m, void *arg)
+{
+ int n;
+ n = dump_counters(m, __start___debugfs, __stop___debugfs, m->private);
+ return n;
+}
+
+static int debugfs_counter_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, show_debugfs_counter, inode->i_private);
+}
+
+static const struct file_operations debugfs_counter_fops = {
+ .open = debugfs_counter_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release
+};
+
+static void
+init_counters(struct debugfs_counter *cnt, struct debugfs_counter *stop)
+{
+ const char *last = NULL;
+
+ for (; cnt < stop; cnt++) {
+ if (cnt->fn == last)
+ continue;
+ last = cnt->fn;
+
+ /* Ignore error. Nothing we can do. */
+ debugfs_create_file(cnt->fn, 0444, NULL, (void *)cnt->fn,
+ &debugfs_counter_fops);
+ }
+}
+
+static int init_debugfs_counters(void)
+{
+ init_counters(__start___debugfs, __stop___debugfs);
+ return 0;
+}
+module_init(init_debugfs_counters);
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index b5e2e4c..fbfb95b 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -272,6 +272,12 @@
\
TRACEDATA \
\
+ __debugfs : AT(ADDR(__debugfs) - LOAD_OFFSET) { \
+ VMLINUX_SYMBOL(__start___debugfs) = .; \
+ *(__debugfs) \
+ VMLINUX_SYMBOL(__stop___debugfs) = .; \
+ } \
+ \
/* Kernel symbol table: Normal symbols */ \
__ksymtab : AT(ADDR(__ksymtab) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start___ksymtab) = .; \
diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
index e7d9b20..a243b05 100644
--- a/include/linux/debugfs.h
+++ b/include/linux/debugfs.h
@@ -18,6 +18,7 @@
#include <linux/fs.h>
#include <linux/types.h>
+#include <linux/percpu.h>
struct file_operations;
@@ -76,6 +77,24 @@ struct dentry *debugfs_create_blob(const char *name, mode_t mode,
bool debugfs_initialized(void);
+struct debugfs_counter {
+ unsigned __percpu *ptr;
+ const char *fn;
+ const char *name;
+} __attribute__((aligned(sizeof(char *))));
+
+/* Note: static doesn't work unlike DEFINE_PERCPU. Sorry. */
+#define DEFINE_DEBUGFS_COUNTER(name_, file) \
+ DEFINE_PER_CPU(unsigned, name_ ## _counter); \
+ struct debugfs_counter name_ ## _pcpu_counter __used \
+ __attribute__((aligned(sizeof(char *)),section("__debugfs"),unused)) \
+ = { .ptr = &name_ ## _counter, .fn = file, .name = #name_ }; \
+
+#define DECLARE_DEBUGFS_COUNTER(name) \
+ struct debugfs_counter name ## _pcpu_counter
+
+#define debugfs_counter_inc(name) this_cpu_inc(name ## _counter)
+
#else
#include <linux/err.h>
@@ -193,6 +212,14 @@ static inline bool debugfs_initialized(void)
return false;
}
+
+struct debugfs_counter {
+};
+
+#define DEFINE_DEBUGFS_COUNTER(name, file)
+#define DECLARE_DEBUGFS_COUNTER(name)
+#define debugfs_counter_inc(name) do {} while(0)
+
#endif
#endif
--
1.7.4.4
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