2014-06-10 09:37:49

by Zhouyi Zhou

[permalink] [raw]

Subject: [RFC PATCH] perf/amd: Try to fix some mem allocation failure handling

---

This is version 2.0 of "[PATCH 1/1] perf/amd: NULL return of kzalloc_node should be handled"
(http://www.spinics.net/lists/kernel/msg1760689.html),

Try to correctly handle mem allocation failure in perf_event_amd_uncore.c

Signed-off-by: Zhouyi Zhou <[email protected]>
---
arch/x86/kernel/cpu/perf_event_amd_uncore.c | 36 ++++++++++++++++++++++++---
1 file changed, 33 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_amd_uncore.c b/arch/x86/kernel/cpu/perf_event_amd_uncore.c
index 3bbdf4c..bdc8e49 100644
--- a/arch/x86/kernel/cpu/perf_event_amd_uncore.c
+++ b/arch/x86/kernel/cpu/perf_event_amd_uncore.c
@@ -294,12 +294,14 @@ static struct amd_uncore *amd_uncore_alloc(unsigned int cpu)
cpu_to_node(cpu));
}

-static void amd_uncore_cpu_up_prepare(unsigned int cpu)
+static int amd_uncore_cpu_up_prepare(unsigned int cpu)
{
struct amd_uncore *uncore;

if (amd_uncore_nb) {
uncore = amd_uncore_alloc(cpu);
+ if (!uncore)
+ return 1;
uncore->cpu = cpu;
uncore->num_counters = NUM_COUNTERS_NB;
uncore->rdpmc_base = RDPMC_BASE_NB;
@@ -311,6 +313,11 @@ static void amd_uncore_cpu_up_prepare(unsigned int cpu)

if (amd_uncore_l2) {
uncore = amd_uncore_alloc(cpu);
+ if (!uncore) {
+ if (amd_uncore_nb)
+ kfree(*per_cpu_ptr(amd_uncore_nb, cpu));
+ return 1;
+ }
uncore->cpu = cpu;
uncore->num_counters = NUM_COUNTERS_L2;
uncore->rdpmc_base = RDPMC_BASE_L2;
@@ -319,6 +326,8 @@ static void amd_uncore_cpu_up_prepare(unsigned int cpu)
uncore->pmu = &amd_l2_pmu;
*per_cpu_ptr(amd_uncore_l2, cpu) = uncore;
}
+
+ return 0;
}

static struct amd_uncore *
@@ -461,7 +470,8 @@ amd_uncore_cpu_notifier(struct notifier_block *self, unsigned long action,

switch (action & ~CPU_TASKS_FROZEN) {
case CPU_UP_PREPARE:
- amd_uncore_cpu_up_prepare(cpu);
+ if (amd_uncore_cpu_up_prepare(cpu))
+ return notifier_from_errno(-ENOMEM),
break;

case CPU_STARTING:
@@ -514,6 +524,8 @@ static int __init amd_uncore_init(void)

if (cpu_has_perfctr_nb) {
amd_uncore_nb = alloc_percpu(struct amd_uncore *);
+ if (!amd_uncore_nb)
+ return -ENOMEM;
perf_pmu_register(&amd_nb_pmu, amd_nb_pmu.name, -1);

printk(KERN_INFO "perf: AMD NB counters detected\n");
@@ -522,6 +534,13 @@ static int __init amd_uncore_init(void)

if (cpu_has_perfctr_l2) {
amd_uncore_l2 = alloc_percpu(struct amd_uncore *);
+ if (!amd_uncore_l2) {
+ if (cpu_has_perfctr_nb) {
+ perf_pmu_unregister(&amd_nb_pmu);
+ free_percpu(amd_uncore_nb);
+ }
+ return -ENOMEM;
+ }
perf_pmu_register(&amd_l2_pmu, amd_l2_pmu.name, -1);

printk(KERN_INFO "perf: AMD L2I counters detected\n");
@@ -535,7 +554,18 @@ static int __init amd_uncore_init(void)

/* init cpus already online before registering for hotplug notifier */
for_each_online_cpu(cpu) {
- amd_uncore_cpu_up_prepare(cpu);
+ if (amd_uncore_cpu_up_prepare(cpu)) {
+ if (cpu_has_perfctr_nb) {
+ perf_pmu_unregister(&amd_nb_pmu);
+ free_percpu(amd_uncore_nb);
+ }
+ if (cpu_has_perfctr_l2) {
+ perf_pmu_unregister(&amd_l2_pmu);
+ free_percpu(amd_uncore_l2);
+ }
+ cpu_notifier_register_done();
+ return -ENOMEM;
+ }
smp_call_function_single(cpu, init_cpu_already_online, NULL, 1);
}

--
1.7.10.4

2014-06-10 10:37:06

by Peter Zijlstra

[permalink] [raw]

Subject: Re: [RFC PATCH] perf/amd: Try to fix some mem allocation failure handling

---

On Tue, Jun 10, 2014 at 05:37:09PM +0800, Zhouyi Zhou wrote:
> This is version 2.0 of "[PATCH 1/1] perf/amd: NULL return of kzalloc_node should be handled"
> (http://www.spinics.net/lists/kernel/msg1760689.html),
>
> Try to correctly handle mem allocation failure in perf_event_amd_uncore.c
>
> Signed-off-by: Zhouyi Zhou <[email protected]>
> ---
> arch/x86/kernel/cpu/perf_event_amd_uncore.c | 36 ++++++++++++++++++++++++---
> 1 file changed, 33 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/perf_event_amd_uncore.c b/arch/x86/kernel/cpu/perf_event_amd_uncore.c
> index 3bbdf4c..bdc8e49 100644
> --- a/arch/x86/kernel/cpu/perf_event_amd_uncore.c
> +++ b/arch/x86/kernel/cpu/perf_event_amd_uncore.c
> @@ -294,12 +294,14 @@ static struct amd_uncore *amd_uncore_alloc(unsigned int cpu)
> cpu_to_node(cpu));
> }
>
> -static void amd_uncore_cpu_up_prepare(unsigned int cpu)
> +static int amd_uncore_cpu_up_prepare(unsigned int cpu)
> {
> struct amd_uncore *uncore;
>
> if (amd_uncore_nb) {
> uncore = amd_uncore_alloc(cpu);
> + if (!uncore)
> + return 1;
> uncore->cpu = cpu;
> uncore->num_counters = NUM_COUNTERS_NB;
> uncore->rdpmc_base = RDPMC_BASE_NB;
> @@ -311,6 +313,11 @@ static void amd_uncore_cpu_up_prepare(unsigned int cpu)
>
> if (amd_uncore_l2) {
> uncore = amd_uncore_alloc(cpu);
> + if (!uncore) {
> + if (amd_uncore_nb)
> + kfree(*per_cpu_ptr(amd_uncore_nb, cpu));
> + return 1;
> + }
> uncore->cpu = cpu;
> uncore->num_counters = NUM_COUNTERS_L2;
> uncore->rdpmc_base = RDPMC_BASE_L2;
> @@ -319,6 +326,8 @@ static void amd_uncore_cpu_up_prepare(unsigned int cpu)
> uncore->pmu = &amd_l2_pmu;
> *per_cpu_ptr(amd_uncore_l2, cpu) = uncore;
> }
> +
> + return 0;
> }

Maybe return -ENOMEM here already.

> static struct amd_uncore *
> @@ -461,7 +470,8 @@ amd_uncore_cpu_notifier(struct notifier_block *self, unsigned long action,
>
> switch (action & ~CPU_TASKS_FROZEN) {
> case CPU_UP_PREPARE:
> - amd_uncore_cpu_up_prepare(cpu);
> + if (amd_uncore_cpu_up_prepare(cpu))
> + return notifier_from_errno(-ENOMEM),
> break;
>
> case CPU_STARTING:
> @@ -514,6 +524,8 @@ static int __init amd_uncore_init(void)
>
> if (cpu_has_perfctr_nb) {
> amd_uncore_nb = alloc_percpu(struct amd_uncore *);
> + if (!amd_uncore_nb)
> + return -ENOMEM;
> perf_pmu_register(&amd_nb_pmu, amd_nb_pmu.name, -1);
>
> printk(KERN_INFO "perf: AMD NB counters detected\n");
> @@ -522,6 +534,13 @@ static int __init amd_uncore_init(void)
>
> if (cpu_has_perfctr_l2) {
> amd_uncore_l2 = alloc_percpu(struct amd_uncore *);
> + if (!amd_uncore_l2) {
> + if (cpu_has_perfctr_nb) {
> + perf_pmu_unregister(&amd_nb_pmu);

Combined with the below (extra for_each_cpu loop) you might want to
think of the 'normal' error handling goto chain.

err_online:
for_each_online_cpu(cpu2) {
if (cpu2 == cpu)
break;

/* cleanup cpu2 */
}
err_l2:
perf_pmu_unregister(nb);
free_percpu(nb);
err_nb:
return ret;


> + free_percpu(amd_uncore_nb);
> + }
> + return -ENOMEM;
> + }
> perf_pmu_register(&amd_l2_pmu, amd_l2_pmu.name, -1);

Then you can propagate the error here, instead of assuming -ENOMEM.

> printk(KERN_INFO "perf: AMD L2I counters detected\n");
> @@ -535,7 +554,18 @@ static int __init amd_uncore_init(void)
>
> /* init cpus already online before registering for hotplug notifier */
> for_each_online_cpu(cpu) {
> - amd_uncore_cpu_up_prepare(cpu);
> + if (amd_uncore_cpu_up_prepare(cpu)) {
> + if (cpu_has_perfctr_nb) {
> + perf_pmu_unregister(&amd_nb_pmu);
> + free_percpu(amd_uncore_nb);
> + }
> + if (cpu_has_perfctr_l2) {
> + perf_pmu_unregister(&amd_l2_pmu);
> + free_percpu(amd_uncore_l2);
> + }
> + cpu_notifier_register_done();
> + return -ENOMEM;
> + }
> smp_call_function_single(cpu, init_cpu_already_online, NULL, 1);
> }

I think you want a second for_each_online_cpu() loop and undo the work
for the other CPUs before calling unregister etc..

---

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