Messages in this thread | | | Date | Thu, 7 Nov 2013 12:59:30 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH v2] kernel/rcutorture.c: be sure of enough memory for result printing |
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On Thu, Nov 07, 2013 at 10:30:25AM +0800, 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 now comsumes 50 - 60 bytes, and this patch provides 200 bytes. > global printing now comsumes a few KB, and this patch provide 8KB, > so for 1K cpus, it may waste 100 - 200 KB memory. > > 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@asianux.com>
Thank you, queued for 3.14.
Thanx, Paul
> --- > kernel/rcu/torture.c | 68 +++++++++++++++++++++++++------------------------ > 1 files changed, 35 insertions(+), 33 deletions(-) > > diff --git a/kernel/rcu/torture.c b/kernel/rcu/torture.c > index 3929cd4..a60874c 100644 > --- a/kernel/rcu/torture.c > +++ b/kernel/rcu/torture.c > @@ -139,8 +139,6 @@ 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; > @@ -376,7 +374,7 @@ 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; > @@ -578,21 +576,19 @@ 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) > @@ -1052,10 +1048,9 @@ 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 }; > @@ -1071,8 +1066,8 @@ 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, > @@ -1080,53 +1075,52 @@ 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); > } > > /* > @@ -1140,10 +1134,18 @@ rcu_torture_printk(char *page) > static void > rcu_torture_stats_print(void) > { > - int cnt; > + int size = nr_cpu_ids * 200 + 8192; /* 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("rcu-torture: no enough memory for printing, requre: %d", > + size); > + return; > + } > + rcu_torture_printk(buf); > + pr_alert("%s", buf); > + kfree(buf); > } > > /* > -- > 1.7.7.6 >
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