On Tue, 30 Apr 2024 10:28:38 +0100 Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> wrote: > On Tue, 30 Apr 2024 14:17:24 +1000 > Gavin Shan <gshan@xxxxxxxxxx> wrote: > > > On 4/26/24 23:51, Jonathan Cameron wrote: > > > Make the per_cpu(processors, cpu) entries available earlier so that > > > they are available in arch_register_cpu() as ARM64 will need access > > > to the acpi_handle to distinguish between acpi_processor_add() > > > and earlier registration attempts (which will fail as _STA cannot > > > be checked). > > > > > > Reorder the remove flow to clear this per_cpu() after > > > arch_unregister_cpu() has completed, allowing it to be used in > > > there as well. > > > > > > Note that on x86 for the CPU hotplug case, the pr->id prior to > > > acpi_map_cpu() may be invalid. Thus the per_cpu() structures > > > must be initialized after that call or after checking the ID > > > is valid (not hotplug path). > > > > > > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> > > > > > > --- > > > v8: On buggy bios detection when setting per_cpu structures > > > do not carry on. > > > Fix up the clearing of per cpu structures to remove unwanted > > > side effects and ensure an error code isn't use to reference them. > > > --- > > > drivers/acpi/acpi_processor.c | 79 +++++++++++++++++++++-------------- > > > 1 file changed, 48 insertions(+), 31 deletions(-) > > > > > > diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c > > > index ba0a6f0ac841..3b180e21f325 100644 > > > --- a/drivers/acpi/acpi_processor.c > > > +++ b/drivers/acpi/acpi_processor.c > > > @@ -183,8 +183,38 @@ static void __init acpi_pcc_cpufreq_init(void) {} > > > #endif /* CONFIG_X86 */ > > > > > > /* Initialization */ > > > +static DEFINE_PER_CPU(void *, processor_device_array); > > > + > > > +static bool acpi_processor_set_per_cpu(struct acpi_processor *pr, > > > + struct acpi_device *device) > > > +{ > > > + BUG_ON(pr->id >= nr_cpu_ids); > > > > One blank line after BUG_ON() if we need to follow original implementation. > > Sure unintentional - I'll put that back. > > > > > > + /* > > > + * Buggy BIOS check. > > > + * ACPI id of processors can be reported wrongly by the BIOS. > > > + * Don't trust it blindly > > > + */ > > > + if (per_cpu(processor_device_array, pr->id) != NULL && > > > + per_cpu(processor_device_array, pr->id) != device) { > > > + dev_warn(&device->dev, > > > + "BIOS reported wrong ACPI id %d for the processor\n", > > > + pr->id); > > > + /* Give up, but do not abort the namespace scan. */ > > > > It depends on how the return value is handled by the caller if the namespace > > is continued to be scanned. The caller can be acpi_processor_hotadd_init() > > and acpi_processor_get_info() after this patch is applied. So I think this > > specific comment need to be moved to the caller. > > Good point. This gets messy and was an unintended change. > > Previously the options were: > 1) acpi_processor_get_info() failed for other reasons - this code was never called. > 2) acpi_processor_get_info() succeeded without acpi_processor_hotadd_init (non hotplug) > this code then ran and would paper over the problem doing a bunch of cleanup under err. > 3) acpi_processor_get_info() succeeded with acpi_processor_hotadd_init called. > This code then ran and would paper over the problem doing a bunch of cleanup under err. > > We should maintain that or argue cleanly against it. > > This isn't helped the the fact I have no idea which cases we care about for that bios > bug handling. Do any of those bios's ever do hotplug? Guess we have to try and maintain > whatever protection this was offering. > > Also, the original code leaks data in some paths and I have limited idea > of whether it is intentional or not. So to tidy the issue up that you've identified > I'll need to try and make that code consistent first. > > I suspect the only way to do that is going to be to duplicate the allocations we > 'want' to leak to deal with the bios bug detection. > > For example acpi_processor_get_info() failing leaks pr and pr->throttling.shared_cpu_map > before this series. After this series we need pr to leak because it's used for the detection > via processor_device_array. > > I'll work through this but it's going to be tricky to tell if we get right. > Step 1 will be closing the existing leaks and then we will have something > consistent to build on. > I 'think' that fixing the original leaks makes this all much more straight forward. That return 0 for acpi_processor_get_info() never made sense as far as I can tell. The pr isn't used after this point. What about something along lines of. diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c index 161c95c9d60a..97cff4492304 100644 --- a/drivers/acpi/acpi_processor.c +++ b/drivers/acpi/acpi_processor.c @@ -392,8 +392,10 @@ static int acpi_processor_add(struct acpi_device *device, device->driver_data = pr; result = acpi_processor_get_info(device); - if (result) /* Processor is not physically present or unavailable */ - return 0; + if (result) { /* Processor is not physically present or unavailable */ + result = 0; + goto err_free_throttling_mask; + } BUG_ON(pr->id >= nr_cpu_ids); @@ -408,7 +410,7 @@ static int acpi_processor_add(struct acpi_device *device, "BIOS reported wrong ACPI id %d for the processor\n", pr->id); /* Give up, but do not abort the namespace scan. */ - goto err; + goto err_clear_driver_data; } /* * processor_device_array is not cleared on errors to allow buggy BIOS @@ -420,12 +422,12 @@ static int acpi_processor_add(struct acpi_device *device, dev = get_cpu_device(pr->id); if (!dev) { result = -ENODEV; - goto err; + goto err_clear_per_cpu; } result = acpi_bind_one(dev, device); if (result) - goto err; + goto err_clear_per_cpu; pr->dev = dev; @@ -436,10 +438,12 @@ static int acpi_processor_add(struct acpi_device *device, dev_err(dev, "Processor driver could not be attached\n"); acpi_unbind_one(dev); - err: - free_cpumask_var(pr->throttling.shared_cpu_map); - device->driver_data = NULL; + err_clear_per_cpu: per_cpu(processors, pr->id) = NULL; + err_clear_driver_data: + device->driver_data = NULL; + err_free_throttling_mask: + free_cpumask_var(pr->throttling.shared_cpu_map); err_free_pr: kfree(pr); return result; Then the diff on this patch is simply: diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c index 3c49eae1e943..3b75f5aeb7ab 100644 --- a/drivers/acpi/acpi_processor.c +++ b/drivers/acpi/acpi_processor.c @@ -200,7 +200,6 @@ static bool acpi_processor_set_per_cpu(struct acpi_processor *pr, dev_warn(&device->dev, "BIOS reported wrong ACPI id %d for the processor\n", pr->id); - /* Give up, but do not abort the namespace scan. */ return false; } /* @@ -230,13 +229,14 @@ static int acpi_processor_hotadd_init(struct acpi_processor *pr, goto out; if (!acpi_processor_set_per_cpu(pr, device)) { + ret = -EINVAL; acpi_unmap_cpu(pr->id); goto out; } ret = arch_register_cpu(pr->id); if (ret) { - /* Leave the processor device array in place to detect buggy bios */ +x /* Leave the processor device array in place to detect buggy bios */ per_cpu(processors, pr->id) = NULL; acpi_unmap_cpu(pr->id); goto out; @@ -262,7 +262,7 @@ static inline int acpi_processor_hotadd_init(struct acpi_processor *pr, } #endif /* CONFIG_ACPI_HOTPLUG_CPU */ -static int acpi_processor_get_info(struct acpi_device *device) +static int acpi_processor_get_info(struct acpi_device *device, bool bios_bug) { union acpi_object object = { 0 }; struct acpi_buffer buffer = { sizeof(union acpi_object), &object }; @@ -361,7 +361,7 @@ static int acpi_processor_get_info(struct acpi_device *device) return ret; } else { if (!acpi_processor_set_per_cpu(pr, device)) - return 0; + return -EINVAL; } /* > > > > Besides, it seems acpi_processor_set_per_cpu() isn't properly called and > > memory leakage can happen. More details are given below. > > > > > + return false; > > > + } > > > + /* > > > + * processor_device_array is not cleared on errors to allow buggy BIOS > > > + * checks. > > > + */ > > > + per_cpu(processor_device_array, pr->id) = device; > > > + per_cpu(processors, pr->id) = pr; > > > + > > > + return true; > > > +} > > > + > > > #ifdef CONFIG_ACPI_HOTPLUG_CPU > > > -static int acpi_processor_hotadd_init(struct acpi_processor *pr) > > > +static int acpi_processor_hotadd_init(struct acpi_processor *pr, > > > + struct acpi_device *device) > > > { > > > int ret; > > > > > > @@ -198,8 +228,15 @@ static int acpi_processor_hotadd_init(struct acpi_processor *pr) > > > if (ret) > > > goto out; > > > > > > + if (!acpi_processor_set_per_cpu(pr, device)) { > > > + acpi_unmap_cpu(pr->id); > > > + goto out; > > > + } > > > + > > > > With the 'goto out', zero is returned from acpi_processor_hotadd_init() to acpi_processor_get_info(). Indeed a bug :( > > The zero return value is carried from acpi_map_cpu() in acpi_processor_hotadd_init(). If I'm correct, > > we need return errno from acpi_processor_get_info() to acpi_processor_add() so that cleanup can be > > done. For example, the cleanup corresponding to the 'err' tag can be done in acpi_processor_add(). > > Otherwise, we will have memory leakage. The confusion here was that previously acpi_processor_add() was missing error cleanup for acpi_processor_get_info(). With that in place I think it's all much simpler. Thanks for your eagle eyes! Jonathan > > > > > ret = arch_register_cpu(pr->id); > > > if (ret) { > > > + /* Leave the processor device array in place to detect buggy bios */ > > > + per_cpu(processors, pr->id) = NULL; > > > acpi_unmap_cpu(pr->id); > > > goto out; > > > } > > > @@ -217,7 +254,8 @@ static int acpi_processor_hotadd_init(struct acpi_processor *pr) > > > return ret; > > > } > > > #else > > > -static inline int acpi_processor_hotadd_init(struct acpi_processor *pr) > > > +static inline int acpi_processor_hotadd_init(struct acpi_processor *pr, > > > + struct acpi_device *device) > > > { > > > return -ENODEV; > > > } > > > @@ -316,10 +354,13 @@ static int acpi_processor_get_info(struct acpi_device *device) > > > * because cpuid <-> apicid mapping is persistent now. > > > */ > > > if (invalid_logical_cpuid(pr->id) || !cpu_present(pr->id)) { > > > - int ret = acpi_processor_hotadd_init(pr); > > > + int ret = acpi_processor_hotadd_init(pr, device); > > > > > > if (ret) > > > return ret; > > > + } else { > > > + if (!acpi_processor_set_per_cpu(pr, device)) > > > + return 0; > > > } > > > > > > > For non-hotplug case, we still need pass the error to acpi_processor_add() so that > > cleanup corresponding 'err' tag can be done. Otherwise, we will have memory leakage. > > > > > /* > > > @@ -365,8 +406,6 @@ static int acpi_processor_get_info(struct acpi_device *device) > > > * (cpu_data(cpu)) values, like CPU feature flags, family, model, etc. > > > * Such things have to be put in and set up by the processor driver's .probe(). > > > */ > > > -static DEFINE_PER_CPU(void *, processor_device_array); > > > - > > > static int acpi_processor_add(struct acpi_device *device, > > > const struct acpi_device_id *id) > > > { > > > @@ -395,28 +434,6 @@ static int acpi_processor_add(struct acpi_device *device, > > > if (result) /* Processor is not physically present or unavailable */ > > > return 0; > > > > > > - BUG_ON(pr->id >= nr_cpu_ids); > > > - > > > - /* > > > - * Buggy BIOS check. > > > - * ACPI id of processors can be reported wrongly by the BIOS. > > > - * Don't trust it blindly > > > - */ > > > - if (per_cpu(processor_device_array, pr->id) != NULL && > > > - per_cpu(processor_device_array, pr->id) != device) { > > > - dev_warn(&device->dev, > > > - "BIOS reported wrong ACPI id %d for the processor\n", > > > - pr->id); > > > - /* Give up, but do not abort the namespace scan. */ > > > - goto err; > > > - } > > > - /* > > > - * processor_device_array is not cleared on errors to allow buggy BIOS > > > - * checks. > > > - */ > > > - per_cpu(processor_device_array, pr->id) = device; > > > - per_cpu(processors, pr->id) = pr; > > > - > > > dev = get_cpu_device(pr->id); > > > if (!dev) { > > > result = -ENODEV; > > > @@ -469,10 +486,6 @@ static void acpi_processor_remove(struct acpi_device *device) > > > device_release_driver(pr->dev); > > > acpi_unbind_one(pr->dev); > > > > > > - /* Clean up. */ > > > - per_cpu(processor_device_array, pr->id) = NULL; > > > - per_cpu(processors, pr->id) = NULL; > > > - > > > cpu_maps_update_begin(); > > > cpus_write_lock(); > > > > > > @@ -480,6 +493,10 @@ static void acpi_processor_remove(struct acpi_device *device) > > > arch_unregister_cpu(pr->id); > > > acpi_unmap_cpu(pr->id); > > > > > > + /* Clean up. */ > > > + per_cpu(processor_device_array, pr->id) = NULL; > > > + per_cpu(processors, pr->id) = NULL; > > > + > > > cpus_write_unlock(); > > > cpu_maps_update_done(); > > > > > > > Thanks, > > Gavin > > >