Re: [PATCH v4 14/15] drivers/firmware/sdei: Expose struct sdei_event

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Thu, 30 Jul 2020 11:45:29 +1000
Gavin Shan <gshan@redhat.com> wrote:

> This splits struct sdei_event into two structs: sdei_event and
> sdei_internal_event. The former one can be dereferenced from external
> module like arm64/kvm when SDEI virtualization is supported. The later
> one is used by the client driver only.
> 
> This also renames local variables from @event to @event_el if their
> type is "struct sdei_internal_event" to make the variable name a bit
> meaningful. Note that it's not applied to sdei_do_{local,cross}_call()
> because CROSSCALL_INIT stops us doing this unless much more changes
> are needed. I'm avoiding to do that.
> 
> Besides, @event is added as "struct sdei_event" to cache @event_el->event
> if it's accessed for multiple times in the particular function to reduce
> the code change size.
> 
> This shouldn't cause functional changes.
> 
> Signed-off-by: Gavin Shan <gshan@redhat.com>
> ---
> v4: Rename variable @event to @event_el if it's internal event
Looks like a few cases were missed.  

>     Use @event to cache @event_el->event if it's used for multiple times

I'm not totally sure this splitting of the structure was worth the pain :(
(even though I suggested it :)
It perhaps makes things easier in the long run though.  Until we get the
user in place, it does look a bit over architected!

I'm fine with it, but others may well not be!

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huwei.com>

> ---
>  drivers/firmware/arm_sdei.c | 160 ++++++++++++++++++++----------------
>  include/linux/arm_sdei.h    |   6 ++
>  2 files changed, 94 insertions(+), 72 deletions(-)
> 
> diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
> index 2678475940e6..f9827c096275 100644
> --- a/drivers/firmware/arm_sdei.c
> +++ b/drivers/firmware/arm_sdei.c
> @@ -44,16 +44,14 @@ static asmlinkage void (*sdei_firmware_call)(unsigned long function_id,
>  /* entry point from firmware to arch asm code */
>  static unsigned long sdei_entry_point;
>  
> -struct sdei_event {
> +struct sdei_internal_event {
> +	struct sdei_event	event;
> +
>  	/* These three are protected by the sdei_list_lock */
>  	struct list_head	list;
>  	bool			reregister;
>  	bool			reenable;
>  
> -	u32			event_num;
> -	u8			type;
> -	u8			priority;
> -
>  	/* This pointer is handed to firmware as the event argument. */
>  	union {
>  		/* Shared events */
> @@ -73,7 +71,7 @@ static LIST_HEAD(sdei_list);
>  
>  /* Private events are registered/enabled via IPI passing one of these */
>  struct sdei_crosscall_args {
> -	struct sdei_event *event;
> +	struct sdei_internal_event *event;

Even though it is a bit painful should probably aim for consistent naming so
this and the other cases related to crosscall should be event_el;

>  	atomic_t errors;
>  	int first_error;
>  };
> @@ -86,7 +84,7 @@ struct sdei_crosscall_args {
>  	} while (0)
>  
>  static inline int sdei_do_local_call(smp_call_func_t fn,
> -				     struct sdei_event *event)
> +				     struct sdei_internal_event *event)
>  {
>  	struct sdei_crosscall_args arg;
>  
> @@ -97,7 +95,7 @@ static inline int sdei_do_local_call(smp_call_func_t fn,
>  }
>  
>  static inline int sdei_do_cross_call(smp_call_func_t fn,
> -				     struct sdei_event *event)
> +				     struct sdei_internal_event *event)
>  {
>  	struct sdei_crosscall_args arg;
>  
> @@ -162,16 +160,16 @@ static int invoke_sdei_fn(unsigned long function_id, unsigned long arg0,
>  }
>  NOKPROBE_SYMBOL(invoke_sdei_fn);
>  
> -static struct sdei_event *sdei_event_find(u32 event_num)
> +static struct sdei_internal_event *sdei_event_find(u32 event_num)
>  {
> -	struct sdei_event *e, *found = NULL;
> +	struct sdei_internal_event *event_el, *found = NULL;
>  
>  	lockdep_assert_held(&sdei_events_lock);
>  
>  	spin_lock(&sdei_list_lock);
> -	list_for_each_entry(e, &sdei_list, list) {
> -		if (e->event_num == event_num) {
> -			found = e;
> +	list_for_each_entry(event_el, &sdei_list, list) {
> +		if (event_el->event.event_num == event_num) {
> +			found = event_el;
>  			break;
>  		}
>  	}
> @@ -193,24 +191,26 @@ static int sdei_api_event_get_info(u32 event, u32 info, u64 *result)
>  			      0, 0, result);
>  }
>  
> -static struct sdei_event *sdei_event_create(u32 event_num,
> -					    sdei_event_callback *cb,
> -					    void *cb_arg)
> +static struct sdei_internal_event *sdei_event_create(u32 event_num,
> +						     sdei_event_callback *cb,
> +						     void *cb_arg)
>  {
>  	int err;
>  	u64 result;
> +	struct sdei_internal_event *event_el;
>  	struct sdei_event *event;
>  	struct sdei_registered_event *reg;
>  
>  	lockdep_assert_held(&sdei_events_lock);
>  
> -	event = kzalloc(sizeof(*event), GFP_KERNEL);
> -	if (!event) {
> +	event_el = kzalloc(sizeof(*event_el), GFP_KERNEL);
> +	if (!event_el) {
>  		err = -ENOMEM;
>  		goto fail;
>  	}
>  
> -	INIT_LIST_HEAD(&event->list);
> +	event = &event_el->event;
> +	INIT_LIST_HEAD(&event_el->list);
>  	event->event_num = event_num;
>  
>  	err = sdei_api_event_get_info(event_num, SDEI_EVENT_INFO_EV_PRIORITY,
> @@ -237,7 +237,7 @@ static struct sdei_event *sdei_event_create(u32 event_num,
>  
>  		reg->callback = cb;
>  		reg->callback_arg = cb_arg;
> -		event->registered = reg;
> +		event_el->registered = reg;
>  	} else {
>  		int cpu;
>  		struct sdei_registered_event __percpu *regs;
> @@ -257,39 +257,39 @@ static struct sdei_event *sdei_event_create(u32 event_num,
>  			reg->callback_arg = cb_arg;
>  		}
>  
> -		event->private_registered = regs;
> +		event_el->private_registered = regs;
>  	}
>  
>  	spin_lock(&sdei_list_lock);
> -	list_add(&event->list, &sdei_list);
> +	list_add(&event_el->list, &sdei_list);
>  	spin_unlock(&sdei_list_lock);
>  
> -	return event;
> +	return event_el;
>  
>  fail:
> -	kfree(event);
> +	kfree(event_el);
>  	return ERR_PTR(err);
>  }
>  
> -static void sdei_event_destroy_llocked(struct sdei_event *event)
> +static void sdei_event_destroy_llocked(struct sdei_internal_event *event_el)
>  {
>  	lockdep_assert_held(&sdei_events_lock);
>  	lockdep_assert_held(&sdei_list_lock);
>  
> -	list_del(&event->list);
> +	list_del(&event_el->list);
>  
> -	if (event->type == SDEI_EVENT_TYPE_SHARED)
> -		kfree(event->registered);
> +	if (event_el->event.type == SDEI_EVENT_TYPE_SHARED)
> +		kfree(event_el->registered);
>  	else
> -		free_percpu(event->private_registered);
> +		free_percpu(event_el->private_registered);
>  
> -	kfree(event);
> +	kfree(event_el);
>  }
>  
> -static void sdei_event_destroy(struct sdei_event *event)
> +static void sdei_event_destroy(struct sdei_internal_event *event_el)
>  {
>  	spin_lock(&sdei_list_lock);
> -	sdei_event_destroy_llocked(event);
> +	sdei_event_destroy_llocked(event_el);
>  	spin_unlock(&sdei_list_lock);
>  }
>  
> @@ -392,7 +392,7 @@ static void _local_event_enable(void *data)
>  
>  	WARN_ON_ONCE(preemptible());
>  
> -	err = sdei_api_event_enable(arg->event->event_num);
> +	err = sdei_api_event_enable(arg->event->event.event_num);
>  
>  	sdei_cross_call_return(arg, err);
>  }
> @@ -400,25 +400,27 @@ static void _local_event_enable(void *data)
>  int sdei_event_enable(u32 event_num)
>  {
>  	int err = -EINVAL;
> +	struct sdei_internal_event *event_el;
>  	struct sdei_event *event;
>  
>  	mutex_lock(&sdei_events_lock);
> -	event = sdei_event_find(event_num);
> -	if (!event) {
> +	event_el = sdei_event_find(event_num);
> +	if (!event_el) {
>  		mutex_unlock(&sdei_events_lock);
>  		return -ENOENT;
>  	}
>  
>  
>  	cpus_read_lock();
> +	event = &event_el->event;
>  	if (event->type == SDEI_EVENT_TYPE_SHARED)
>  		err = sdei_api_event_enable(event->event_num);
>  	else
> -		err = sdei_do_cross_call(_local_event_enable, event);
> +		err = sdei_do_cross_call(_local_event_enable, event_el);
>  
>  	if (!err) {
>  		spin_lock(&sdei_list_lock);
> -		event->reenable = true;
> +		event_el->reenable = true;
>  		spin_unlock(&sdei_list_lock);
>  	}
>  	cpus_read_unlock();
> @@ -438,7 +440,7 @@ static void _ipi_event_disable(void *data)
>  	int err;
>  	struct sdei_crosscall_args *arg = data;
>  
> -	err = sdei_api_event_disable(arg->event->event_num);
> +	err = sdei_api_event_disable(arg->event->event.event_num);
>  
>  	sdei_cross_call_return(arg, err);
>  }
> @@ -446,23 +448,25 @@ static void _ipi_event_disable(void *data)
>  int sdei_event_disable(u32 event_num)
>  {
>  	int err = -EINVAL;
> +	struct sdei_internal_event *event_el;
>  	struct sdei_event *event;
>  
>  	mutex_lock(&sdei_events_lock);
> -	event = sdei_event_find(event_num);
> -	if (!event) {
> +	event_el = sdei_event_find(event_num);
> +	if (!event_el) {
>  		mutex_unlock(&sdei_events_lock);
>  		return -ENOENT;
>  	}
>  
>  	spin_lock(&sdei_list_lock);
> -	event->reenable = false;
> +	event_el->reenable = false;
>  	spin_unlock(&sdei_list_lock);
>  
> +	event = &event_el->event;
>  	if (event->type == SDEI_EVENT_TYPE_SHARED)
>  		err = sdei_api_event_disable(event->event_num);
>  	else
> -		err = sdei_do_cross_call(_ipi_event_disable, event);
> +		err = sdei_do_cross_call(_ipi_event_disable, event_el);
>  	mutex_unlock(&sdei_events_lock);
>  
>  	return err;
> @@ -482,7 +486,7 @@ static void _local_event_unregister(void *data)
>  
>  	WARN_ON_ONCE(preemptible());
>  
> -	err = sdei_api_event_unregister(arg->event->event_num);
> +	err = sdei_api_event_unregister(arg->event->event.event_num);
>  
>  	sdei_cross_call_return(arg, err);
>  }
> @@ -490,32 +494,34 @@ static void _local_event_unregister(void *data)
>  int sdei_event_unregister(u32 event_num)
>  {
>  	int err;
> +	struct sdei_internal_event *event_el;
>  	struct sdei_event *event;
>  
>  	WARN_ON(in_nmi());
>  
>  	mutex_lock(&sdei_events_lock);
> -	event = sdei_event_find(event_num);
> -	if (!event) {
> +	event_el = sdei_event_find(event_num);
> +	if (!event_el) {
>  		pr_warn("Event %u not registered\n", event_num);
>  		err = -ENOENT;
>  		goto unlock;
>  	}
>  
>  	spin_lock(&sdei_list_lock);
> -	event->reregister = false;
> -	event->reenable = false;
> +	event_el->reregister = false;
> +	event_el->reenable = false;
>  	spin_unlock(&sdei_list_lock);
>  
> +	event = &event_el->event;
>  	if (event->type == SDEI_EVENT_TYPE_SHARED)
>  		err = sdei_api_event_unregister(event->event_num);
>  	else
> -		err = sdei_do_cross_call(_local_event_unregister, event);
> +		err = sdei_do_cross_call(_local_event_unregister, event_el);
>  
>  	if (err)
>  		goto unlock;
>  
> -	sdei_event_destroy(event);
> +	sdei_event_destroy(event_el);
>  unlock:
>  	mutex_unlock(&sdei_events_lock);
>  
> @@ -529,11 +535,13 @@ int sdei_event_unregister(u32 event_num)
>  static int sdei_unregister_shared(void)
>  {
>  	int err = 0;
> +	struct sdei_internal_event *event_el;
>  	struct sdei_event *event;
>  
>  	mutex_lock(&sdei_events_lock);
>  	spin_lock(&sdei_list_lock);
> -	list_for_each_entry(event, &sdei_list, list) {
> +	list_for_each_entry(event_el, &sdei_list, list) {
> +		event = &event_el->event;
>  		if (event->type != SDEI_EVENT_TYPE_SHARED)
>  			continue;
>  
> @@ -565,8 +573,8 @@ static void _local_event_register(void *data)
>  	WARN_ON(preemptible());
>  
>  	reg = per_cpu_ptr(arg->event->private_registered, smp_processor_id());
> -	err = sdei_api_event_register(arg->event->event_num, sdei_entry_point,
> -				      reg, 0, 0);
> +	err = sdei_api_event_register(arg->event->event.event_num,
> +				      sdei_entry_point, reg, 0, 0);
>  
>  	sdei_cross_call_return(arg, err);
>  }
> @@ -574,6 +582,7 @@ static void _local_event_register(void *data)
>  int sdei_event_register(u32 event_num, sdei_event_callback *cb, void *arg)
>  {
>  	int err;
> +	struct sdei_internal_event *event_el;
>  	struct sdei_event *event;
>  
>  	WARN_ON(in_nmi());
> @@ -585,33 +594,34 @@ int sdei_event_register(u32 event_num, sdei_event_callback *cb, void *arg)
>  		goto unlock;
>  	}
>  
> -	event = sdei_event_create(event_num, cb, arg);
> -	if (IS_ERR(event)) {
> -		err = PTR_ERR(event);
> +	event_el = sdei_event_create(event_num, cb, arg);
> +	if (IS_ERR(event_el)) {
> +		err = PTR_ERR(event_el);
>  		pr_warn("Failed to create event %u: %d\n", event_num, err);
>  		goto unlock;
>  	}
>  
>  	cpus_read_lock();
> +	event = &event_el->event;
>  	if (event->type == SDEI_EVENT_TYPE_SHARED) {
>  		err = sdei_api_event_register(event->event_num,
>  					      sdei_entry_point,
> -					      event->registered,
> +					      event_el->registered,
>  					      SDEI_EVENT_REGISTER_RM_ANY, 0);
>  	} else {
> -		err = sdei_do_cross_call(_local_event_register, event);
> +		err = sdei_do_cross_call(_local_event_register, event_el);
>  		if (err)
> -			sdei_do_cross_call(_local_event_unregister, event);
> +			sdei_do_cross_call(_local_event_unregister, event_el);
>  	}
>  
>  	if (err) {
> -		sdei_event_destroy(event);
> +		sdei_event_destroy(event_el);
>  		pr_warn("Failed to register event %u: %d\n", event_num, err);
>  		goto cpu_unlock;
>  	}
>  
>  	spin_lock(&sdei_list_lock);
> -	event->reregister = true;
> +	event_el->reregister = true;
>  	spin_unlock(&sdei_list_lock);
>  cpu_unlock:
>  	cpus_read_unlock();
> @@ -623,27 +633,29 @@ int sdei_event_register(u32 event_num, sdei_event_callback *cb, void *arg)
>  static int sdei_reregister_shared(void)
>  {
>  	int err = 0;
> +	struct sdei_internal_event *event_el;
>  	struct sdei_event *event;

Could reduce the scope by moving this in the loop.  Not that important though.

>  
>  	mutex_lock(&sdei_events_lock);
>  	spin_lock(&sdei_list_lock);
> -	list_for_each_entry(event, &sdei_list, list) {
> +	list_for_each_entry(event_el, &sdei_list, list) {
> +		event = &event_el->event;
>  		if (event->type != SDEI_EVENT_TYPE_SHARED)
>  			continue;
>  
> -		if (event->reregister) {
> +		if (event_el->reregister) {
>  			err = sdei_api_event_register(event->event_num,
> -					sdei_entry_point, event->registered,
> +					sdei_entry_point, event_el->registered,
>  					SDEI_EVENT_REGISTER_RM_ANY, 0);
>  			if (err) {
> -				sdei_event_destroy_llocked(event);
> +				sdei_event_destroy_llocked(event_el);
>  				pr_err("Failed to re-register event %u\n",
>  				       event->event_num);
>  				break;
>  			}
>  		}
>  
> -		if (event->reenable) {
> +		if (event_el->reenable) {
>  			err = sdei_api_event_enable(event->event_num);
>  			if (err) {
>  				pr_err("Failed to re-enable event %u\n",
> @@ -660,16 +672,18 @@ static int sdei_reregister_shared(void)
>  
>  static int sdei_cpuhp_down(unsigned int cpu)
>  {
> +	struct sdei_internal_event *event_el;
>  	struct sdei_event *event;
>  	int err;
>  
>  	/* un-register private events */
>  	spin_lock(&sdei_list_lock);
> -	list_for_each_entry(event, &sdei_list, list) {
> +	list_for_each_entry(event_el, &sdei_list, list) {
> +		event = &event_el->event;
>  		if (event->type == SDEI_EVENT_TYPE_SHARED)
>  			continue;
>  
> -		err = sdei_do_local_call(_local_event_unregister, event);
> +		err = sdei_do_local_call(_local_event_unregister, event_el);
>  		if (err) {
>  			pr_err("Failed to unregister event %u: %d\n",
>  			       event->event_num, err);
> @@ -682,25 +696,27 @@ static int sdei_cpuhp_down(unsigned int cpu)
>  
>  static int sdei_cpuhp_up(unsigned int cpu)
>  {
> +	struct sdei_internal_event *event_el;
>  	struct sdei_event *event;
>  	int err;
>  
>  	/* re-register/enable private events */
>  	spin_lock(&sdei_list_lock);
> -	list_for_each_entry(event, &sdei_list, list) {
> +	list_for_each_entry(event_el, &sdei_list, list) {
> +		event = &event_el->event;
>  		if (event->type == SDEI_EVENT_TYPE_SHARED)
>  			continue;
>  
> -		if (event->reregister) {
> -			err = sdei_do_local_call(_local_event_register, event);
> +		if (event_el->reregister) {
> +			err = sdei_do_local_call(_local_event_register, event_el);
>  			if (err) {
>  				pr_err("Failed to re-register event %u: %d\n",
>  				       event->event_num, err);
>  			}
>  		}
>  
> -		if (event->reenable) {
> -			err = sdei_do_local_call(_local_event_enable, event);
> +		if (event_el->reenable) {
> +			err = sdei_do_local_call(_local_event_enable, event_el);
>  			if (err) {
>  				pr_err("Failed to re-enable event %u: %d\n",
>  				       event->event_num, err);
> diff --git a/include/linux/arm_sdei.h b/include/linux/arm_sdei.h
> index 0a241c5c911d..d2464a18b6ff 100644
> --- a/include/linux/arm_sdei.h
> +++ b/include/linux/arm_sdei.h
> @@ -22,6 +22,12 @@
>   */
>  typedef int (sdei_event_callback)(u32 event, struct pt_regs *regs, void *arg);
>  
> +struct sdei_event {
> +	u32			event_num;
> +	u8			type;
> +	u8			priority;
> +};
> +
>  /*
>   * Register your callback to claim an event. The event must be described
>   * by firmware.



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