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Message-ID: <53A37140.3020003@gmail.com>
Date: Thu, 19 Jun 2014 19:24:48 -0400
From: Pranith Kumar <bobby.prani@...il.com>
To: paulmck@...ux.vnet.ibm.com, Joe Perches <joe@...ches.com>
CC: LKML <linux-kernel@...r.kernel.org>, romanov.arya@...il.com,
Josh Triplett <josh@...htriplett.org>
Subject: [RFC PATCH] use snprintf instead of sprintf in rcu_torture_printk
(dropping some CCs)
On 06/19/2014 05:00 PM, Paul E. McKenney wrote:
> On Wed, Jun 18, 2014 at 12:49:42PM -0700, Joe Perches wrote:
>>
>> I believe the function doesn't work well.
>>
>> static void
>> rcu_torture_stats_print(void)
>> {
>> int size = nr_cpu_ids * 200 + 8192;
>> char *buf;
>>
>> buf = kmalloc(size, GFP_KERNEL);
>> if (!buf) {
>> pr_err("rcu-torture: Out of memory, need: %d\n", size);
>> return;
>> }
>> rcu_torture_printk(buf);
>> pr_alert("%s", buf);
>> kfree(buf);
>> }
>>
>> rcu_torture_printk simply fills buf
>>
>> btw: I believe the arguments should pass size and
>> rcu_torture_printk should use snprintf/size
>>
>> but all printks are limited to a maximum of 1024
>> bytes so the large allocation is senseless and
>> would even if it worked, would likely need to be
>> vmalloc/vfree
>
> Fair point!
>
> Pranith, Romanov, if you would like part of RCU that is less touchy
> about random hacking, this would be a good place to start. Scripts in
> tools/testing/selftests/rcutorture/bin do care about some of the format,
> but the variable-length portion generated by cur_ops->stats() is as far
> as I know only parsed by human eyes.
>
Here is a first run of the change. Please let me know if I am totally off. RFC. :)
Three things on Todo list:
* We need to check that we are using less than the allocated size of the buffer (used > size). (we are allocating a big buffer, so not sure if necessary)
* Need to check with the scripts if they are working.
* I used a loop for pr_alert(). I am not sure this is right, there should be a better way for printing large buffers
If the overall structure is ok I will go ahead and check how the scripts are handling these changes.
>From 0d52fdcd941b0eaaacb6732f59f609595ac14d11 Mon Sep 17 00:00:00 2001
From: Pranith Kumar <bobby.prani@...il.com>
Date: Thu, 19 Jun 2014 19:00:46 -0400
Subject: [PATCH 1/1] use snprintf instead of sprintf in rcu_torture_print_stats
Signed-off-by: Pranith Kumar <bobby.prani@...il.com>
---
include/linux/torture.h | 2 +-
kernel/rcu/rcutorture.c | 76 ++++++++++++++++++++++++++++---------------------
kernel/torture.c | 7 +++--
3 files changed, 48 insertions(+), 37 deletions(-)
diff --git a/include/linux/torture.h b/include/linux/torture.h
index 5ca58fc..1e47ec7 100644
--- a/include/linux/torture.h
+++ b/include/linux/torture.h
@@ -51,7 +51,7 @@
/* Definitions for online/offline exerciser. */
int torture_onoff_init(long ooholdoff, long oointerval);
-char *torture_onoff_stats(char *page);
+int torture_onoff_stats(char *page, int size);
bool torture_onoff_failures(void);
/* Low-rider random number generator. */
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 7fa34f8..f708db4 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -242,7 +242,7 @@ struct rcu_torture_ops {
void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
void (*cb_barrier)(void);
void (*fqs)(void);
- void (*stats)(char *page);
+ int (*stats)(char *page, int size);
int irq_capable;
int can_boost;
const char *name;
@@ -525,21 +525,22 @@ static void srcu_torture_barrier(void)
srcu_barrier(&srcu_ctl);
}
-static void srcu_torture_stats(char *page)
+static int srcu_torture_stats(char *page, int size)
{
- int cpu;
+ int cpu, used = 0;
int idx = srcu_ctl.completed & 0x1;
- page += sprintf(page, "%s%s per-CPU(idx=%d):",
+ used = snprintf(page, size, "%s%s per-CPU(idx=%d):",
torture_type, TORTURE_FLAG, idx);
for_each_possible_cpu(cpu) {
long c0, c1;
c0 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx];
c1 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx];
- page += sprintf(page, " %d(%ld,%ld)", cpu, c0, c1);
+ used += snprintf(page + used, size - used, " %d(%ld,%ld)", cpu, c0, c1);
}
- sprintf(page, "\n");
+ used += snprintf(page + used, size - used, "\n");
+ return used;
}
static void srcu_torture_synchronize_expedited(void)
@@ -1033,10 +1034,10 @@ rcu_torture_reader(void *arg)
/*
* Create an RCU-torture statistics message in the specified buffer.
*/
-static void
-rcu_torture_printk(char *page)
+static int
+rcu_torture_printk(char *page, int size)
{
- int cpu;
+ int cpu, used = 0;
int i;
long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
@@ -1052,8 +1053,8 @@ rcu_torture_printk(char *page)
if (pipesummary[i] != 0)
break;
}
- page += sprintf(page, "%s%s ", torture_type, TORTURE_FLAG);
- page += sprintf(page,
+ used += snprintf(page + used, size - used, "%s%s ", torture_type, TORTURE_FLAG);
+ used += snprintf(page + used, size - used,
"rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
rcu_torture_current,
rcu_torture_current_version,
@@ -1061,46 +1062,47 @@ rcu_torture_printk(char *page)
atomic_read(&n_rcu_torture_alloc),
atomic_read(&n_rcu_torture_alloc_fail),
atomic_read(&n_rcu_torture_free));
- page += sprintf(page, "rtmbe: %d rtbke: %ld rtbre: %ld ",
+ used += snprintf(page + used, size - used, "rtmbe: %d rtbke: %ld rtbre: %ld ",
atomic_read(&n_rcu_torture_mberror),
n_rcu_torture_boost_ktrerror,
n_rcu_torture_boost_rterror);
- page += sprintf(page, "rtbf: %ld rtb: %ld nt: %ld ",
+ used += snprintf(page + used, size - used, "rtbf: %ld rtb: %ld nt: %ld ",
n_rcu_torture_boost_failure,
n_rcu_torture_boosts,
n_rcu_torture_timers);
- page = torture_onoff_stats(page);
- page += sprintf(page, "barrier: %ld/%ld:%ld",
+ used += torture_onoff_stats(page + used, size - used);
+ used += snprintf(page + used, size - used,
+ "barrier: %ld/%ld:%ld",
n_barrier_successes,
n_barrier_attempts,
n_rcu_torture_barrier_error);
- page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
+ used += snprintf(page + used, size - used, "\n%s%s ", torture_type, TORTURE_FLAG);
if (atomic_read(&n_rcu_torture_mberror) != 0 ||
n_rcu_torture_barrier_error != 0 ||
n_rcu_torture_boost_ktrerror != 0 ||
n_rcu_torture_boost_rterror != 0 ||
n_rcu_torture_boost_failure != 0 ||
i > 1) {
- page += sprintf(page, "!!! ");
+ used += snprintf(page + used, size - used, "!!! ");
atomic_inc(&n_rcu_torture_error);
WARN_ON_ONCE(1);
}
- page += sprintf(page, "Reader Pipe: ");
+ used += snprintf(page + used, size - used, "Reader Pipe: ");
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
- page += sprintf(page, " %ld", pipesummary[i]);
- page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
- page += sprintf(page, "Reader Batch: ");
+ used += snprintf(page + used, size - used, " %ld", pipesummary[i]);
+ used += snprintf(page + used, size - used, "\n%s%s ", torture_type, TORTURE_FLAG);
+ used += snprintf(page + used, size - used, "Reader Batch: ");
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
- page += sprintf(page, " %ld", batchsummary[i]);
- page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
- page += sprintf(page, "Free-Block Circulation: ");
+ used += snprintf(page + used, size - used, " %ld", batchsummary[i]);
+ used += snprintf(page + used, size - used, "\n%s%s ", torture_type, TORTURE_FLAG);
+ used += snprintf(page + used, size - used, "Free-Block Circulation: ");
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
- page += sprintf(page, " %d",
+ used += snprintf(page + used, size - used, " %d",
atomic_read(&rcu_torture_wcount[i]));
}
- page += sprintf(page, "\n");
+ used += snprintf(page + used, size - used, "\n");
if (cur_ops->stats)
- cur_ops->stats(page);
+ used += cur_ops->stats(page, size - used);
if (rtcv_snap == rcu_torture_current_version &&
rcu_torture_current != NULL) {
int __maybe_unused flags;
@@ -1109,7 +1111,7 @@ rcu_torture_printk(char *page)
rcutorture_get_gp_data(cur_ops->ttype,
&flags, &gpnum, &completed);
- page += sprintf(page,
+ used += snprintf(page + used, size - used,
"??? Writer stall state %d g%lu c%lu f%#x\n",
rcu_torture_writer_state,
gpnum, completed, flags);
@@ -1117,6 +1119,8 @@ rcu_torture_printk(char *page)
rcutorture_trace_dump();
}
rtcv_snap = rcu_torture_current_version;
+
+ return used;
}
/*
@@ -1130,17 +1134,23 @@ rcu_torture_printk(char *page)
static void
rcu_torture_stats_print(void)
{
- int size = nr_cpu_ids * 200 + 8192;
+ int size = nr_cpu_ids * 200 + 8192, used = 0, size_pr;
char *buf;
- buf = kmalloc(size, GFP_KERNEL);
+ buf = vmalloc(size);
if (!buf) {
pr_err("rcu-torture: Out of memory, need: %d", size);
return;
}
- rcu_torture_printk(buf);
- pr_alert("%s", buf);
- kfree(buf);
+ used = rcu_torture_printk(buf, size);
+
+ /* printk can print only print LOG_LINE_MAX chars at a time */
+ while (used > 0) {
+ size_pr = pr_alert("%s", buf);
+ used -= size_pr;
+ buf += size_pr;
+ }
+ vfree(buf);
}
/*
diff --git a/kernel/torture.c b/kernel/torture.c
index 40bb511..da95335 100644
--- a/kernel/torture.c
+++ b/kernel/torture.c
@@ -211,10 +211,11 @@ EXPORT_SYMBOL_GPL(torture_onoff_cleanup);
/*
* Print online/offline testing statistics.
*/
-char *torture_onoff_stats(char *page)
+int torture_onoff_stats(char *page, int size)
{
+ int used = 0;
#ifdef CONFIG_HOTPLUG_CPU
- page += sprintf(page,
+ used = snprintf(page, size,
"onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
n_online_successes, n_online_attempts,
n_offline_successes, n_offline_attempts,
@@ -222,7 +223,7 @@ char *torture_onoff_stats(char *page)
min_offline, max_offline,
sum_online, sum_offline, HZ);
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
- return page;
+ return used;
}
EXPORT_SYMBOL_GPL(torture_onoff_stats);
--
1.9.1
--
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