Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755383Ab3JUJgo (ORCPT ); Mon, 21 Oct 2013 05:36:44 -0400 Received: from intranet.asianux.com ([58.214.24.6]:42296 "EHLO intranet.asianux.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752858Ab3JUJgn (ORCPT ); Mon, 21 Oct 2013 05:36:43 -0400 X-Spam-Score: -100.8 Message-ID: <5264F569.5030708@asianux.com> Date: Mon, 21 Oct 2013 17:35:37 +0800 From: Chen Gang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com CC: josh@freedesktop.org, "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] kernel/rcutorture.c: be sure of enough memory for result printing. References: <5253C335.5050609@asianux.com> <20131013110518.GC5790@linux.vnet.ibm.com> <525BAD9F.6060406@asianux.com> <20131014112839.GO5790@linux.vnet.ibm.com> <525C9256.5010002@asianux.com> <525C9FAE.4090209@asianux.com> <20131015082613.GG5790@linux.vnet.ibm.com> <525D35E9.3000604@asianux.com> <20131015144732.GG9150@linux.vnet.ibm.com> <525DF4F0.3070901@asianux.com> <525F3830.2060001@asianux.com> <5264C0DD.9060006@asianux.com> <5264C72F.1020509@asianux.com> In-Reply-To: <5264C72F.1020509@asianux.com> Content-Type: text/plain; charset=GB2312 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8254 Lines: 229 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 >> --- >> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/