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Date: Mon, 04 Nov 2013 17:42:39 +0800
From: Chen Gang <gang.chen@...anux.com>
To: paulmck@...ux.vnet.ibm.com
CC: josh@...edesktop.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kernel/rcutorture.c: be sure of enough memory for result
printing.
Hello Maintainers:
Is the patch OK? If you want to fix it by yourself, please let me know.
Thanks.
On 10/27/2013 10:43 PM, Chen Gang wrote:
> Hello Maintainers:
>
> Is it patch OK or not? when you have time, please help check (if it is
> necessary to send patch v2, please let me know).
>
> Thanks.
>
> On 10/21/2013 05:35 PM, Chen Gang wrote:
>>
>> BTW: I use kmalloc(), and still can pass build-in and let boot runnable
>> under my laptop, but I think it is not quite precise, may still need
>> more think of, please check (or give a confirmation whether it is OK).
>>
>> Hmm... maybe the pr_err("...") also need "srcu-torture" prefix just like
>> another printing to let checkers easy search?
>>
>> Thanks.
>>
>> On 10/21/2013 02:18 PM, Chen Gang wrote:
>>>
>>> Oh, sorry, I forgot to let it pass "./scripts/checkpatch.pl", after
>>> finish checking, it finds a style issue (which is pointed out below), if
>>> necessary to send patch v2, please let me know.
>>>
>>> Thanks.
>>>
>>> On 10/21/2013 01:51 PM, Chen Gang wrote:
>>>> If the contents is more than 4096 bytes (e.g. if have 1K cpus), current
>>>> sprintf() will cause memory overflow. And this fix patch is to be sure
>>>> of memory large enough.
>>>>
>>>> Benefit:
>>>>
>>>> - do not truncate printing contents.
>>>> - extensible, it is large enough for printing various related contents.
>>>> - simple and clear enough for both source code readers and writers.
>>>>
>>>> Shortcoming:
>>>>
>>>> - It will waste some memory:
>>>> 1 cpu may waste 24KB,
>>>> 10 cpus may waste 96KB,
>>>> 100 cpus may waste 816KB,
>>>> 1K cpus may waste 8MB
>>>> ...
>>>> after finish printing, it will free the related memory, quickly.
>>>> it is a test module, so wast a little memory for extensible is OK.
>>>>
>>>> Related test (Fedora16 2 CPUs, 2GB RAM x86_64)
>>>>
>>>> - as module, with/without "torture_type=srcu".
>>>> - build-in not boot runnable, with/without "torture_type=srcu".
>>>> - build-in let boot runnable, with/without "torture_type=srcu".
>>>>
>>>>
>>>> Signed-off-by: Chen Gang <gang.chen@...anux.com>
>>>> ---
>>>> kernel/rcutorture.c | 67 ++++++++++++++++++++++++++-------------------------
>>>> 1 files changed, 34 insertions(+), 33 deletions(-)
>>>>
>>>> diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
>>>> index be63101..3413bc1 100644
>>>> --- a/kernel/rcutorture.c
>>>> +++ b/kernel/rcutorture.c
>>>> @@ -133,8 +133,6 @@ MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
>>>> #define VERBOSE_PRINTK_ERRSTRING(s) \
>>>> do { if (verbose) pr_alert("%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
>>>>
>>>> -static char printk_buf[4096];
>>>> -
>>>> static int nrealreaders;
>>>> static struct task_struct *writer_task;
>>>> static struct task_struct **fakewriter_tasks;
>>>> @@ -370,7 +368,7 @@ struct rcu_torture_ops {
>>>> void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
>>>> void (*cb_barrier)(void);
>>>> void (*fqs)(void);
>>>> - int (*stats)(char *page);
>>>> + void (*stats)(char *page);
>>>> int irq_capable;
>>>> int can_boost;
>>>> const char *name;
>>>> @@ -572,21 +570,19 @@ static void srcu_torture_barrier(void)
>>>> srcu_barrier(&srcu_ctl);
>>>> }
>>>>
>>>> -static int srcu_torture_stats(char *page)
>>>> +static void srcu_torture_stats(char *page)
>>>> {
>>>> - int cnt = 0;
>>>> int cpu;
>>>> int idx = srcu_ctl.completed & 0x1;
>>>>
>>>> - cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
>>>> + page += sprintf(page, "%s%s per-CPU(idx=%d):",
>>>> torture_type, TORTURE_FLAG, idx);
>>>> for_each_possible_cpu(cpu) {
>>>> - cnt += sprintf(&page[cnt], " %d(%lu,%lu)", cpu,
>>>> + page += sprintf(page, " %d(%lu,%lu)", cpu,
>>>> per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
>>>> per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
>>>> }
>>>> - cnt += sprintf(&page[cnt], "\n");
>>>> - return cnt;
>>>> + sprintf(page, "\n");
>>>> }
>>>>
>>>> static void srcu_torture_synchronize_expedited(void)
>>>> @@ -1046,10 +1042,9 @@ rcu_torture_reader(void *arg)
>>>> /*
>>>> * Create an RCU-torture statistics message in the specified buffer.
>>>> */
>>>> -static int
>>>> +static void
>>>> rcu_torture_printk(char *page)
>>>> {
>>>> - int cnt = 0;
>>>> int cpu;
>>>> int i;
>>>> long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
>>>> @@ -1065,8 +1060,8 @@ rcu_torture_printk(char *page)
>>>> if (pipesummary[i] != 0)
>>>> break;
>>>> }
>>>> - cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
>>>> - cnt += sprintf(&page[cnt],
>>>> + page += sprintf(page, "%s%s ", torture_type, TORTURE_FLAG);
>>>> + page += sprintf(page,
>>>> "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
>>>> rcu_torture_current,
>>>> rcu_torture_current_version,
>>>> @@ -1074,53 +1069,52 @@ rcu_torture_printk(char *page)
>>>> atomic_read(&n_rcu_torture_alloc),
>>>> atomic_read(&n_rcu_torture_alloc_fail),
>>>> atomic_read(&n_rcu_torture_free));
>>>> - cnt += sprintf(&page[cnt], "rtmbe: %d rtbke: %ld rtbre: %ld ",
>>>> + page += sprintf(page, "rtmbe: %d rtbke: %ld rtbre: %ld ",
>>>> atomic_read(&n_rcu_torture_mberror),
>>>> n_rcu_torture_boost_ktrerror,
>>>> n_rcu_torture_boost_rterror);
>>>> - cnt += sprintf(&page[cnt], "rtbf: %ld rtb: %ld nt: %ld ",
>>>> + page += sprintf(page, "rtbf: %ld rtb: %ld nt: %ld ",
>>>> n_rcu_torture_boost_failure,
>>>> n_rcu_torture_boosts,
>>>> n_rcu_torture_timers);
>>>> - cnt += sprintf(&page[cnt],
>>>> + page += sprintf(page,
>>>> "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,
>>>> min_online, max_online,
>>>> min_offline, max_offline,
>>>> sum_online, sum_offline, HZ);
>>>> - cnt += sprintf(&page[cnt], "barrier: %ld/%ld:%ld",
>>>> + page += sprintf(page, "barrier: %ld/%ld:%ld",
>>>> n_barrier_successes,
>>>> n_barrier_attempts,
>>>> n_rcu_torture_barrier_error);
>>>> - cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
>>>> + page += sprintf(page, "\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) {
>>>> - cnt += sprintf(&page[cnt], "!!! ");
>>>> + page += sprintf(page, "!!! ");
>>>> atomic_inc(&n_rcu_torture_error);
>>>> WARN_ON_ONCE(1);
>>>> }
>>>> - cnt += sprintf(&page[cnt], "Reader Pipe: ");
>>>> + page += sprintf(page, "Reader Pipe: ");
>>>> for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
>>>> - cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
>>>> - cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
>>>> - cnt += sprintf(&page[cnt], "Reader Batch: ");
>>>> + page += sprintf(page, " %ld", pipesummary[i]);
>>>> + page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
>>>> + page += sprintf(page, "Reader Batch: ");
>>>> for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
>>>> - cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
>>>> - cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
>>>> - cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
>>>> + page += sprintf(page, " %ld", batchsummary[i]);
>>>> + page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
>>>> + page += sprintf(page, "Free-Block Circulation: ");
>>>> for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
>>>> - cnt += sprintf(&page[cnt], " %d",
>>>> + page += sprintf(page, " %d",
>>>> atomic_read(&rcu_torture_wcount[i]));
>>>> }
>>>> - cnt += sprintf(&page[cnt], "\n");
>>>> + page += sprintf(page, "\n");
>>>> if (cur_ops->stats)
>>>> - cnt += cur_ops->stats(&page[cnt]);
>>>> - return cnt;
>>>> + cur_ops->stats(page);
>>>
>>> Oh, sorry, this line has a waste white space.
>>>
>>>> }
>>>>
>>>> /*
>>>> @@ -1134,10 +1128,17 @@ rcu_torture_printk(char *page)
>>>> static void
>>>> rcu_torture_stats_print(void)
>>>> {
>>>> - int cnt;
>>>> + int size = (nr_cpu_ids + 2) * PAGE_SIZE; /* be sure of large enough */
>>>> + char *buf;
>>>>
>>>> - cnt = rcu_torture_printk(printk_buf);
>>>> - pr_alert("%s", printk_buf);
>>>> + buf = kmalloc(size, GFP_KERNEL);
>>>> + if (!buf) {
>>>> + pr_err("no enough memory for printing, requre: %d", size);
>>>> + return;
>>>> + }
>>>> + rcu_torture_printk(buf);
>>>> + pr_alert("%s", buf);
>>>> + kfree(buf);
>>>> }
>>>>
>>>> /*
>>>>
>>>
>>>
>>
>>
>
>
--
Chen Gang
--
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