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Date: Fri, 27 Aug 2010 21:47:50 +0200 From: Robert Richter <robert.richter@....com> To: Will Deacon <will.deacon@....com> CC: Matt Fleming <matt@...sole-pimps.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Paul Mundt <lethal@...ux-sh.org>, Russell King <linux@....linux.org.uk>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "linux-sh@...r.kernel.org" <linux-sh@...r.kernel.org>, Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>, Frederic Weisbecker <fweisbec@...il.com>, Arnaldo Carvalho de Melo <acme@...hat.com>, "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>, oprofile-list <oprofile-list@...ts.sourceforge.net> Subject: Re: [PATCH 1/4] oprofile: Handle initialisation failure more gracefully On 27.08.10 14:06:45, Will Deacon wrote: > Hi Robert, > > Thanks for taking the time to look at this. > > On Fri, 2010-08-27 at 17:38 +0100, Robert Richter wrote: > > On 27.08.10 11:15:25, Will Deacon wrote: > > > > How about something like this? This removes the exit call > > > from the init code and sets pointers to NULL after they have been > > > freed. We still have to do some checking so that we don't try to > > > release a NULL perf event: > > > > > > diff --git a/arch/arm/oprofile/common.c b/arch/arm/oprofile/common.c > > > index 0691176..12253eb 100644 > > > --- a/arch/arm/oprofile/common.c > > > +++ b/arch/arm/oprofile/common.c > > > @@ -275,10 +275,12 @@ out: > > > return ret; > > > } > > > > > > -static void exit_driverfs(void) > > > +static void __exit exit_driverfs(void) > > > { > > > - platform_device_unregister(oprofile_pdev); > > > - platform_driver_unregister(&oprofile_driver); > > > + if (!IS_ERR_OR_NULL(oprofile_pdev)) { > > > > This check is obsolete here as we do not call oprofile_arch_exit() on > > failure. > > > Sorry, I was being braindead and thought oprofile_arch_exit might be > called via oprofile_exit. As it happens, this is only called because of > module_exit so we know that initialisation will have completed. > > In light of this and your comments, I've simplified the code. Once > people are happy with it, I'll post it as a couple of patches: Looks good to me know, the code is a lot easier. Please send me a final version. I'm going to apply it on Monday. Thanks Will, -Robert > > diff --git a/arch/arm/oprofile/common.c b/arch/arm/oprofile/common.c > index 0691176..c2c4a2e 100644 > --- a/arch/arm/oprofile/common.c > +++ b/arch/arm/oprofile/common.c > @@ -275,7 +275,7 @@ out: > return ret; > } > > -static void exit_driverfs(void) > +static void __exit exit_driverfs(void) > { > platform_device_unregister(oprofile_pdev); > platform_driver_unregister(&oprofile_driver); > @@ -359,14 +359,13 @@ int __init oprofile_arch_init(struct oprofile_operations *ops) > if (!counter_config) { > pr_info("oprofile: failed to allocate %d " > "counters\n", perf_num_counters); > - return -ENOMEM; > + ret = -ENOMEM; > + goto out; > } > > ret = init_driverfs(); > - if (ret) { > - kfree(counter_config); > - return ret; > - } > + if (ret) > + goto out; > > for_each_possible_cpu(cpu) { > perf_events[cpu] = kcalloc(perf_num_counters, > @@ -374,9 +373,8 @@ int __init oprofile_arch_init(struct oprofile_operations *ops) > 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]); > - return -ENOMEM; > + ret = -ENOMEM; > + goto out; > } > } > > @@ -393,28 +391,33 @@ int __init oprofile_arch_init(struct oprofile_operations *ops) > else > pr_info("oprofile: using %s\n", ops->cpu_type); > > +out: > + if (ret) { > + kfree(counter_config); > + for_each_possible_cpu(cpu) > + kfree(perf_events[cpu]); > + } > + > return ret; > } > > -void oprofile_arch_exit(void) > +void __exit oprofile_arch_exit(void) > { > int cpu, id; > struct perf_event *event; > > - if (*perf_events) { > - exit_driverfs(); > - for_each_possible_cpu(cpu) { > - for (id = 0; id < perf_num_counters; ++id) { > - event = perf_events[cpu][id]; > - if (event != NULL) > - perf_event_release_kernel(event); > - } > - kfree(perf_events[cpu]); > + for_each_possible_cpu(cpu) { > + for (id = 0; id < perf_num_counters; ++id) { > + event = perf_events[cpu][id]; > + if (event) > + perf_event_release_kernel(event); > } > + > + kfree(perf_events[cpu]); > } > > - if (counter_config) > - kfree(counter_config); > + kfree(counter_config); > + exit_driverfs(); > } > #else > int __init oprofile_arch_init(struct oprofile_operations *ops) > @@ -422,5 +425,5 @@ int __init oprofile_arch_init(struct oprofile_operations *ops) > pr_info("oprofile: hardware counters not available\n"); > return -ENODEV; > } > -void oprofile_arch_exit(void) {} > +void __exit oprofile_arch_exit(void) {} > #endif /* CONFIG_HW_PERF_EVENTS */ > diff --git a/drivers/oprofile/oprof.c b/drivers/oprofile/oprof.c > index b336cd9..b4a6857 100644 > --- a/drivers/oprofile/oprof.c > +++ b/drivers/oprofile/oprof.c > @@ -257,16 +257,9 @@ static int __init oprofile_init(void) > printk(KERN_INFO "oprofile: using timer interrupt.\n"); > err = oprofile_timer_init(&oprofile_ops); > if (err) > - goto out_arch; > + return err; > } > - err = oprofilefs_register(); > - if (err) > - goto out_arch; > - return 0; > - > -out_arch: > - oprofile_arch_exit(); > - return err; > + return oprofilefs_register(); > } > > > Once again, thanks for looking at this and have a good weekend, > > Will > > > -- Advanced Micro Devices, Inc. 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