Messages in this thread | | | Subject | Re: [PATCH 1/2] coresight: trbe: Fix TRBE potential sleep in atomic context | From | hejunhao <> | Date | Mon, 14 Aug 2023 21:32:29 +0800 |
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Hi Suzuki
On 2023/8/14 18:34, Suzuki K Poulose wrote: > Hi Junhao > > On 14/08/2023 10:38, Junhao He wrote: >> smp_call_function_single() will allocate an IPI interrupt vector to >> the target processor and send a function call request to the interrupt >> vector. After the target processor receives the IPI interrupt, it will >> execute arm_trbe_remove_coresight_cpu() call request in the interrupt >> handler. >> >> According to the device_unregister() stack information, if other process >> is useing the device, the down_write() may sleep, and trigger deadlocks >> or unexpected errors. >> >> arm_trbe_remove_coresight_cpu >> coresight_unregister >> device_unregister >> device_del >> kobject_del >> __kobject_del >> sysfs_remove_dir >> kernfs_remove >> down_write ---------> it may sleep >> >> Add a helper arm_trbe_disable_cpu() to disable TRBE precpu irq and reset >> per TRBE. >> Simply call arm_trbe_remove_coresight_cpu() directly without useing the >> smp_call_function_single(), which is the same as registering the TRBE >> coresight device. >> >> Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver") >> Signed-off-by: Junhao He <hejunhao3@huawei.com> >> --- >> drivers/hwtracing/coresight/coresight-trbe.c | 35 +++++++++++--------- >> 1 file changed, 20 insertions(+), 15 deletions(-) >> >> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c >> b/drivers/hwtracing/coresight/coresight-trbe.c >> index 7720619909d6..ce1e6f537b8d 100644 >> --- a/drivers/hwtracing/coresight/coresight-trbe.c >> +++ b/drivers/hwtracing/coresight/coresight-trbe.c >> @@ -1225,6 +1225,17 @@ static void arm_trbe_enable_cpu(void *info) >> enable_percpu_irq(drvdata->irq, IRQ_TYPE_NONE); >> } >> +static void arm_trbe_disable_cpu(void *info) >> +{ >> + struct trbe_drvdata *drvdata = info; >> + struct trbe_cpudata *cpudata = this_cpu_ptr(drvdata->cpudata); >> + >> + disable_percpu_irq(drvdata->irq); >> + trbe_reset_local(cpudata); >> + cpudata->drvdata = NULL; >> +} >> + >> + >> static void arm_trbe_register_coresight_cpu(struct trbe_drvdata >> *drvdata, int cpu) >> { >> struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu); >> @@ -1326,18 +1337,12 @@ static void arm_trbe_probe_cpu(void *info) >> cpumask_clear_cpu(cpu, &drvdata->supported_cpus); >> } >> -static void arm_trbe_remove_coresight_cpu(void *info) >> +static void arm_trbe_remove_coresight_cpu(struct trbe_drvdata >> *drvdata, int cpu) >> { >> - int cpu = smp_processor_id(); >> - struct trbe_drvdata *drvdata = info; >> - struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu); >> struct coresight_device *trbe_csdev = >> coresight_get_percpu_sink(cpu); >> - disable_percpu_irq(drvdata->irq); >> - trbe_reset_local(cpudata); >> if (trbe_csdev) { >> coresight_unregister(trbe_csdev); >> - cpudata->drvdata = NULL; >> coresight_set_percpu_sink(cpu, NULL); > > I am a bit concerned about "resetting" the sink from a different CPU. > Could we instead, schedule a delayed work to unregister the trbe_csdev?
Yes, I will try to do that. Sorry for my following questions. As you mean, do we need to take the same care when setting the percpu sink in the register trbe_csdev ?
Best regards, Junhao.
> > >> } >> } >> @@ -1366,8 +1371,12 @@ static int arm_trbe_remove_coresight(struct >> trbe_drvdata *drvdata) >> { >> int cpu; >> - for_each_cpu(cpu, &drvdata->supported_cpus) >> - smp_call_function_single(cpu, arm_trbe_remove_coresight_cpu, >> drvdata, 1); >> + for_each_cpu(cpu, &drvdata->supported_cpus) { >> + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus)) >> + smp_call_function_single(cpu, arm_trbe_disable_cpu, >> drvdata, 1); >> + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus)) >> + arm_trbe_remove_coresight_cpu(drvdata, cpu); >> + } >> free_percpu(drvdata->cpudata); >> return 0; >> } >> @@ -1406,12 +1415,8 @@ static int arm_trbe_cpu_teardown(unsigned int >> cpu, struct hlist_node *node) >> { >> struct trbe_drvdata *drvdata = hlist_entry_safe(node, struct >> trbe_drvdata, hotplug_node); >> - if (cpumask_test_cpu(cpu, &drvdata->supported_cpus)) { >> - struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, >> cpu); >> - >> - disable_percpu_irq(drvdata->irq); >> - trbe_reset_local(cpudata); >> - } >> + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus)) >> + arm_trbe_disable_cpu(drvdata); >> return 0; >> } > > > . >
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