Messages in this thread | | | Date | Fri, 27 Aug 2010 13:44:05 +0100 | From | Matt Fleming <> | Subject | Re: [PATCH V2 3/4] oprofile: Abstract the perf-events backend |
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On Fri, Aug 27, 2010 at 11:41:31AM +0100, Will Deacon wrote: > Hi Matt, > > I'm still not happy with the init/exit alloc/free code: > > On Thu, 2010-08-26 at 20:09 +0100, Matt Fleming wrote: > > [...] > > > +int oprofile_perf_init(void) > > +{ > > + u32 counter_size = sizeof(struct op_counter_config); > > + int cpu; > > + > > + counter_config = kcalloc(perf_num_counters, counter_size, GFP_KERNEL); > > + > > + if (!counter_config) { > > + pr_info("oprofile: failed to allocate %d " > > + "counters\n", perf_num_counters); > > + return -ENOMEM; > > + } > > + > > + for_each_possible_cpu(cpu) { > > + perf_events[cpu] = kcalloc(perf_num_counters, > > + sizeof(struct perf_event *), GFP_KERNEL); > > + if (!perf_events[cpu]) { > > + pr_info("oprofile: failed to allocate %d perf events " > > + "for cpu %d\n", perf_num_counters, cpu); > > + while (--cpu >= 0) > > + kfree(perf_events[cpu]); > > + kfree(counter_config); > > + return -ENOMEM; > > + } > > + } > > + > > + return 0; > > +} > > So here, if the perf_events allocation fails for a cpu, we free the > stuff we've already allocated [including counter_config] and return > -ENOMEM. Looking at drivers/oprofile/oprof.c: > > static int __init oprofile_init(void) > { > int err; > > err = oprofile_arch_init(&oprofile_ops); > if (err < 0 || timer) { > printk(KERN_INFO "oprofile: using timer interrupt.\n"); > err = oprofile_timer_init(&oprofile_ops); > if (err) > goto out_arch; > } > err = oprofilefs_register(); > if (err) > goto out_arch; > return 0; > > out_arch: > oprofile_arch_exit(); > return err; > } > > So now, if timer_init fails or oprofilefs_register fails, we will > call oprofile_arch_exit, which calls oprofile_perf_exit: > > > +void oprofile_perf_exit(void) > > +{ > > + int id, cpu; > > + > > + for_each_possible_cpu(cpu) { > > + for (id = 0; id < perf_num_counters; ++id) > > + oprofile_destroy_counter(cpu, id); > > + > > + kfree(perf_events[cpu]); > > + } > > + > > + kfree(counter_config); > > +} > > meaning that we will free everything again! This is what I > was trying to avoid in patch 1/4, by moving the counter_config > freeing into the *_exit function. Looking at it again, I think > all the freeing should be moved to the *_exit function and the init > function should just return error when allocation fails. What do you > think?
*facepalm*
I dunno how I forgot to fix up that patch. Sorry. You're completely right, I forgot to role your changes from patch 1/4 into 3/4 when I shuffled the code around. Thank you for being diligent.
> > +/* > > + * Create active perf events based on the perviously configured > > + * attributes. > > + */ > > typo :)
Thanks.
> For what it's worth, I tested the series on my Cortex-A9 board and > everything seemed to work fine. I'll give the patches another spin when > we've sorted out these memory issues.
Excellent news. Thanks for testing! I'll get the next version of patch 3/4 out tonight.
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