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Subject[ 53/82] random: add tracepoints for easier debugging and verification
Date
From: Greg KH <gregkh@linuxfoundation.org>

3.5-stable review patch. If anyone has any objections, please let me know.

------------------
From: Theodore Ts'o <tytso@mit.edu>

commit 00ce1db1a634746040ace24c09a4e3a7949a3145 upstream.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/char/random.c | 26 ++++++--
include/trace/events/random.h | 134 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 156 insertions(+), 4 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -266,6 +266,9 @@
#include <asm/irq_regs.h>
#include <asm/io.h>

+#define CREATE_TRACE_POINTS
+#include <trace/events/random.h>
+
/*
* Configuration information
*/
@@ -478,8 +481,8 @@ static __u32 const twist_table[8] = {
* it's cheap to do so and helps slightly in the expected case where
* the entropy is concentrated in the low-order bits.
*/
-static void __mix_pool_bytes(struct entropy_store *r, const void *in,
- int nbytes, __u8 out[64])
+static void _mix_pool_bytes(struct entropy_store *r, const void *in,
+ int nbytes, __u8 out[64])
{
unsigned long i, j, tap1, tap2, tap3, tap4, tap5;
int input_rotate;
@@ -531,13 +534,21 @@ static void __mix_pool_bytes(struct entr
((__u32 *)out)[j] = r->pool[(i - j) & wordmask];
}

-static void mix_pool_bytes(struct entropy_store *r, const void *in,
+static void __mix_pool_bytes(struct entropy_store *r, const void *in,
int nbytes, __u8 out[64])
{
+ trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_);
+ _mix_pool_bytes(r, in, nbytes, out);
+}
+
+static void mix_pool_bytes(struct entropy_store *r, const void *in,
+ int nbytes, __u8 out[64])
+{
unsigned long flags;

+ trace_mix_pool_bytes(r->name, nbytes, _RET_IP_);
spin_lock_irqsave(&r->lock, flags);
- __mix_pool_bytes(r, in, nbytes, out);
+ _mix_pool_bytes(r, in, nbytes, out);
spin_unlock_irqrestore(&r->lock, flags);
}

@@ -585,6 +596,7 @@ static void credit_entropy_bits(struct e
retry:
entropy_count = orig = ACCESS_ONCE(r->entropy_count);
entropy_count += nbits;
+
if (entropy_count < 0) {
DEBUG_ENT("negative entropy/overflow\n");
entropy_count = 0;
@@ -599,6 +611,9 @@ retry:
r->initialized = 1;
}

+ trace_credit_entropy_bits(r->name, nbits, entropy_count,
+ r->entropy_total, _RET_IP_);
+
/* should we wake readers? */
if (r == &input_pool && entropy_count >= random_read_wakeup_thresh) {
wake_up_interruptible(&random_read_wait);
@@ -971,6 +986,7 @@ static ssize_t extract_entropy(struct en
ssize_t ret = 0, i;
__u8 tmp[EXTRACT_SIZE];

+ trace_extract_entropy(r->name, nbytes, r->entropy_count, _RET_IP_);
xfer_secondary_pool(r, nbytes);
nbytes = account(r, nbytes, min, reserved);

@@ -1005,6 +1021,7 @@ static ssize_t extract_entropy_user(stru
ssize_t ret = 0, i;
__u8 tmp[EXTRACT_SIZE];

+ trace_extract_entropy_user(r->name, nbytes, r->entropy_count, _RET_IP_);
xfer_secondary_pool(r, nbytes);
nbytes = account(r, nbytes, 0, 0);

@@ -1062,6 +1079,7 @@ void get_random_bytes_arch(void *buf, in
{
char *p = buf;

+ trace_get_random_bytes(nbytes, _RET_IP_);
while (nbytes) {
unsigned long v;
int chunk = min(nbytes, (int)sizeof(unsigned long));
--- /dev/null
+++ b/include/trace/events/random.h
@@ -0,0 +1,134 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM random
+
+#if !defined(_TRACE_RANDOM_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_RANDOM_H
+
+#include <linux/writeback.h>
+#include <linux/tracepoint.h>
+
+DECLARE_EVENT_CLASS(random__mix_pool_bytes,
+ TP_PROTO(const char *pool_name, int bytes, unsigned long IP),
+
+ TP_ARGS(pool_name, bytes, IP),
+
+ TP_STRUCT__entry(
+ __field( const char *, pool_name )
+ __field( int, bytes )
+ __field(unsigned long, IP )
+ ),
+
+ TP_fast_assign(
+ __entry->pool_name = pool_name;
+ __entry->bytes = bytes;
+ __entry->IP = IP;
+ ),
+
+ TP_printk("%s pool: bytes %d caller %pF",
+ __entry->pool_name, __entry->bytes, (void *)__entry->IP)
+);
+
+DEFINE_EVENT(random__mix_pool_bytes, mix_pool_bytes,
+ TP_PROTO(const char *pool_name, int bytes, unsigned long IP),
+
+ TP_ARGS(pool_name, bytes, IP)
+);
+
+DEFINE_EVENT(random__mix_pool_bytes, mix_pool_bytes_nolock,
+ TP_PROTO(const char *pool_name, int bytes, unsigned long IP),
+
+ TP_ARGS(pool_name, bytes, IP)
+);
+
+TRACE_EVENT(credit_entropy_bits,
+ TP_PROTO(const char *pool_name, int bits, int entropy_count,
+ int entropy_total, unsigned long IP),
+
+ TP_ARGS(pool_name, bits, entropy_count, entropy_total, IP),
+
+ TP_STRUCT__entry(
+ __field( const char *, pool_name )
+ __field( int, bits )
+ __field( int, entropy_count )
+ __field( int, entropy_total )
+ __field(unsigned long, IP )
+ ),
+
+ TP_fast_assign(
+ __entry->pool_name = pool_name;
+ __entry->bits = bits;
+ __entry->entropy_count = entropy_count;
+ __entry->entropy_total = entropy_total;
+ __entry->IP = IP;
+ ),
+
+ TP_printk("%s pool: bits %d entropy_count %d entropy_total %d "
+ "caller %pF", __entry->pool_name, __entry->bits,
+ __entry->entropy_count, __entry->entropy_total,
+ (void *)__entry->IP)
+);
+
+TRACE_EVENT(get_random_bytes,
+ TP_PROTO(int nbytes, unsigned long IP),
+
+ TP_ARGS(nbytes, IP),
+
+ TP_STRUCT__entry(
+ __field( int, nbytes )
+ __field(unsigned long, IP )
+ ),
+
+ TP_fast_assign(
+ __entry->nbytes = nbytes;
+ __entry->IP = IP;
+ ),
+
+ TP_printk("nbytes %d caller %pF", __entry->nbytes, (void *)__entry->IP)
+);
+
+DECLARE_EVENT_CLASS(random__extract_entropy,
+ TP_PROTO(const char *pool_name, int nbytes, int entropy_count,
+ unsigned long IP),
+
+ TP_ARGS(pool_name, nbytes, entropy_count, IP),
+
+ TP_STRUCT__entry(
+ __field( const char *, pool_name )
+ __field( int, nbytes )
+ __field( int, entropy_count )
+ __field(unsigned long, IP )
+ ),
+
+ TP_fast_assign(
+ __entry->pool_name = pool_name;
+ __entry->nbytes = nbytes;
+ __entry->entropy_count = entropy_count;
+ __entry->IP = IP;
+ ),
+
+ TP_printk("%s pool: nbytes %d entropy_count %d caller %pF",
+ __entry->pool_name, __entry->nbytes, __entry->entropy_count,
+ (void *)__entry->IP)
+);
+
+
+DEFINE_EVENT(random__extract_entropy, extract_entropy,
+ TP_PROTO(const char *pool_name, int nbytes, int entropy_count,
+ unsigned long IP),
+
+ TP_ARGS(pool_name, nbytes, entropy_count, IP)
+);
+
+DEFINE_EVENT(random__extract_entropy, extract_entropy_user,
+ TP_PROTO(const char *pool_name, int nbytes, int entropy_count,
+ unsigned long IP),
+
+ TP_ARGS(pool_name, nbytes, entropy_count, IP)
+);
+
+
+
+#endif /* _TRACE_RANDOM_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>



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