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Date:   Sun, 18 Aug 2019 20:41:56 +0100
From:   Jonathan Cameron <jic23@jic23.retrosnub.co.uk>
To:     Bartosz Golaszewski <brgl@bgdev.pl>
Cc:     Linus Walleij <linus.walleij@linaro.org>,
        Hartmut Knaack <knaack.h@gmx.de>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        Marc Zyngier <maz@kernel.org>, linux-gpio@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>
Subject: Re: [PATCH 1/2] irq/irq_sim: make the irq_sim structure opaque
Message-ID: <20190818204156.669fa660@archlinux>
In-Reply-To: <20190818203836.6cceb4d3@archlinux>
References: <20190812125256.9690-1-brgl@bgdev.pl>
        <20190812125256.9690-2-brgl@bgdev.pl>
        <20190818203836.6cceb4d3@archlinux>
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Sender: linux-kernel-owner@vger.kernel.org
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On Sun, 18 Aug 2019 20:38:36 +0100
Jonathan Cameron <jic23@kernel.org> wrote:

> On Mon, 12 Aug 2019 14:52:55 +0200
> Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> 
> > From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> > 
> > There's no good reason to export the interrupt simulator structure to
> > users and have them provide memory for it. Let's make all the related
> > data structures opaque and convert both users. This way we have a lot
> > less APIs exposed in the header.
> > 
> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>  
> 
> I agree in principle, but there is the disadvantage that all drivers
> that use it now need to bother with another allocation.  I guess
> it is still worthwhile though.
> 
> One comment inline.

Ignore that one as it's in code you get rid of in patch 2 ;)

Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> 
> Jonathan
> 
> > ---
> >  drivers/gpio/gpio-mockup.c          | 12 ++---
> >  drivers/iio/dummy/iio_dummy_evgen.c | 18 +++----
> >  include/linux/irq_sim.h             | 24 ++-------
> >  kernel/irq/irq_sim.c                | 83 ++++++++++++++++++-----------
> >  4 files changed, 70 insertions(+), 67 deletions(-)
> > 
> > diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
> > index f1a9c0544e3f..9b28ffec5826 100644
> > --- a/drivers/gpio/gpio-mockup.c
> > +++ b/drivers/gpio/gpio-mockup.c
> > @@ -53,7 +53,7 @@ struct gpio_mockup_line_status {
> >  struct gpio_mockup_chip {
> >  	struct gpio_chip gc;
> >  	struct gpio_mockup_line_status *lines;
> > -	struct irq_sim irqsim;
> > +	struct irq_sim *irqsim;
> >  	struct dentry *dbg_dir;
> >  	struct mutex lock;
> >  };
> > @@ -186,7 +186,7 @@ static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
> >  {
> >  	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
> >  
> > -	return irq_sim_irqnum(&chip->irqsim, offset);
> > +	return irq_sim_irqnum(chip->irqsim, offset);
> >  }
> >  
> >  static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset)
> > @@ -247,7 +247,7 @@ static ssize_t gpio_mockup_debugfs_write(struct file *file,
> >  	chip = priv->chip;
> >  	gc = &chip->gc;
> >  	desc = &gc->gpiodev->descs[priv->offset];
> > -	sim = &chip->irqsim;
> > +	sim = chip->irqsim;
> >  
> >  	mutex_lock(&chip->lock);
> >  
> > @@ -431,9 +431,9 @@ static int gpio_mockup_probe(struct platform_device *pdev)
> >  			return rv;
> >  	}
> >  
> > -	rv = devm_irq_sim_init(dev, &chip->irqsim, gc->ngpio);
> > -	if (rv < 0)
> > -		return rv;
> > +	chip->irqsim = devm_irq_sim_new(dev, gc->ngpio);
> > +	if (IS_ERR(chip->irqsim))
> > +		return PTR_ERR(chip->irqsim);
> >  
> >  	rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
> >  	if (rv)
> > diff --git a/drivers/iio/dummy/iio_dummy_evgen.c b/drivers/iio/dummy/iio_dummy_evgen.c
> > index a6edf30567aa..efbcd4a5609e 100644
> > --- a/drivers/iio/dummy/iio_dummy_evgen.c
> > +++ b/drivers/iio/dummy/iio_dummy_evgen.c
> > @@ -37,7 +37,7 @@ struct iio_dummy_eventgen {
> >  	struct iio_dummy_regs regs[IIO_EVENTGEN_NO];
> >  	struct mutex lock;
> >  	bool inuse[IIO_EVENTGEN_NO];
> > -	struct irq_sim irq_sim;
> > +	struct irq_sim *irq_sim;
> >  	int base;
> >  };
> >  
> > @@ -46,19 +46,17 @@ static struct iio_dummy_eventgen *iio_evgen;
> >  
> >  static int iio_dummy_evgen_create(void)
> >  {
> > -	int ret;
> > -
> >  	iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL);
> >  	if (!iio_evgen)
> >  		return -ENOMEM;
> >  
> > -	ret = irq_sim_init(&iio_evgen->irq_sim, IIO_EVENTGEN_NO);
> > -	if (ret < 0) {
> > +	iio_evgen->irq_sim = irq_sim_new(IIO_EVENTGEN_NO);
> > +	if (IS_ERR(iio_evgen->irq_sim)) {
> >  		kfree(iio_evgen);
> > -		return ret;
> > +		return PTR_ERR(iio_evgen->irq_sim);
> >  	}
> >  
> > -	iio_evgen->base = irq_sim_irqnum(&iio_evgen->irq_sim, 0);
> > +	iio_evgen->base = irq_sim_irqnum(iio_evgen->irq_sim, 0);
> >  	mutex_init(&iio_evgen->lock);
> >  
> >  	return 0;
> > @@ -80,7 +78,7 @@ int iio_dummy_evgen_get_irq(void)
> >  	mutex_lock(&iio_evgen->lock);
> >  	for (i = 0; i < IIO_EVENTGEN_NO; i++) {
> >  		if (!iio_evgen->inuse[i]) {
> > -			ret = irq_sim_irqnum(&iio_evgen->irq_sim, i);
> > +			ret = irq_sim_irqnum(iio_evgen->irq_sim, i);
> >  			iio_evgen->inuse[i] = true;
> >  			break;
> >  		}
> > @@ -115,7 +113,7 @@ EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs);
> >  
> >  static void iio_dummy_evgen_free(void)
> >  {
> > -	irq_sim_fini(&iio_evgen->irq_sim);
> > +	irq_sim_free(iio_evgen->irq_sim);
> >  	kfree(iio_evgen);
> >  }
> >  
> > @@ -140,7 +138,7 @@ static ssize_t iio_evgen_poke(struct device *dev,
> >  	iio_evgen->regs[this_attr->address].reg_id   = this_attr->address;
> >  	iio_evgen->regs[this_attr->address].reg_data = event;
> >  
> > -	irq_sim_fire(&iio_evgen->irq_sim, this_attr->address);
> > +	irq_sim_fire(iio_evgen->irq_sim, this_attr->address);
> >  
> >  	return len;
> >  }
> > diff --git a/include/linux/irq_sim.h b/include/linux/irq_sim.h
> > index 4500d453a63e..4bbf036145e2 100644
> > --- a/include/linux/irq_sim.h
> > +++ b/include/linux/irq_sim.h
> > @@ -14,27 +14,11 @@
> >   * requested like normal irqs and enqueued from process context.
> >   */
> >  
> > -struct irq_sim_work_ctx {
> > -	struct irq_work		work;
> > -	unsigned long		*pending;
> > -};
> > +struct irq_sim;
> >  
> > -struct irq_sim_irq_ctx {
> > -	int			irqnum;
> > -	bool			enabled;
> > -};
> > -
> > -struct irq_sim {
> > -	struct irq_sim_work_ctx	work_ctx;
> > -	int			irq_base;
> > -	unsigned int		irq_count;
> > -	struct irq_sim_irq_ctx	*irqs;
> > -};
> > -
> > -int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs);
> > -int devm_irq_sim_init(struct device *dev, struct irq_sim *sim,
> > -		      unsigned int num_irqs);
> > -void irq_sim_fini(struct irq_sim *sim);
> > +struct irq_sim *irq_sim_new(unsigned int num_irqs);
> > +struct irq_sim *devm_irq_sim_new(struct device *dev, unsigned int num_irqs);
> > +void irq_sim_free(struct irq_sim *sim);
> >  void irq_sim_fire(struct irq_sim *sim, unsigned int offset);
> >  int irq_sim_irqnum(struct irq_sim *sim, unsigned int offset);
> >  
> > diff --git a/kernel/irq/irq_sim.c b/kernel/irq/irq_sim.c
> > index b992f88c5613..79f0a6494b6c 100644
> > --- a/kernel/irq/irq_sim.c
> > +++ b/kernel/irq/irq_sim.c
> > @@ -7,6 +7,23 @@
> >  #include <linux/irq_sim.h>
> >  #include <linux/irq.h>
> >  
> > +struct irq_sim_work_ctx {
> > +	struct irq_work		work;
> > +	unsigned long		*pending;
> > +};
> > +
> > +struct irq_sim_irq_ctx {
> > +	int			irqnum;
> > +	bool			enabled;
> > +};
> > +
> > +struct irq_sim {
> > +	struct irq_sim_work_ctx	work_ctx;
> > +	int			irq_base;
> > +	unsigned int		irq_count;
> > +	struct irq_sim_irq_ctx	*irqs;
> > +};
> > +
> >  struct irq_sim_devres {
> >  	struct irq_sim		*sim;
> >  };
> > @@ -63,34 +80,42 @@ static void irq_sim_handle_irq(struct irq_work *work)
> >  }
> >  
> >  /**
> > - * irq_sim_init - Initialize the interrupt simulator: allocate a range of
> > - *                dummy interrupts.
> > + * irq_sim_new - Create a new interrupt simulator: allocate a range of
> > + *               dummy interrupts.
> >   *
> > - * @sim:        The interrupt simulator object to initialize.
> >   * @num_irqs:   Number of interrupts to allocate
> >   *
> > - * On success: return the base of the allocated interrupt range.
> > - * On failure: a negative errno.
> > + * On success: return the new irq_sim object.
> > + * On failure: a negative errno wrapped with ERR_PTR().
> >   */
> > -int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs)
> > +struct irq_sim *irq_sim_new(unsigned int num_irqs)
> >  {
> > +	struct irq_sim *sim;
> >  	int i;
> >  
> > +	sim = kmalloc(sizeof(*sim), GFP_KERNEL);
> > +	if (!sim)
> > +		return ERR_PTR(-ENOMEM);
> > +
> >  	sim->irqs = kmalloc_array(num_irqs, sizeof(*sim->irqs), GFP_KERNEL);
> > -	if (!sim->irqs)
> > -		return -ENOMEM;
> > +	if (!sim->irqs) {
> > +		kfree(sim);
> > +		return ERR_PTR(-ENOMEM);
> > +	}
> >  
> >  	sim->irq_base = irq_alloc_descs(-1, 0, num_irqs, 0);
> >  	if (sim->irq_base < 0) {
> >  		kfree(sim->irqs);
> > -		return sim->irq_base;
> > +		kfree(sim);
> > +		return ERR_PTR(sim->irq_base);
> >  	}
> >  
> >  	sim->work_ctx.pending = bitmap_zalloc(num_irqs, GFP_KERNEL);
> >  	if (!sim->work_ctx.pending) {
> >  		kfree(sim->irqs);
> > +		kfree(sim);  
> 
> This rather looks like a function that could benefit from some
> unified error paths.  That was true already, but adding another step
> makes it an even better idea. Goto fun :)
> 
> >  		irq_free_descs(sim->irq_base, num_irqs);
> > -		return -ENOMEM;
> > +		return ERR_PTR(-ENOMEM);
> >  	}
> >  
> >  	for (i = 0; i < num_irqs; i++) {
> > @@ -106,64 +131,60 @@ int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs)
> >  	init_irq_work(&sim->work_ctx.work, irq_sim_handle_irq);
> >  	sim->irq_count = num_irqs;
> >  
> > -	return sim->irq_base;
> > +	return sim;
> >  }
> > -EXPORT_SYMBOL_GPL(irq_sim_init);
> > +EXPORT_SYMBOL_GPL(irq_sim_new);
> >  
> >  /**
> > - * irq_sim_fini - Deinitialize the interrupt simulator: free the interrupt
> > + * irq_sim_free - Deinitialize the interrupt simulator: free the interrupt
> >   *                descriptors and allocated memory.
> >   *
> >   * @sim:        The interrupt simulator to tear down.
> >   */
> > -void irq_sim_fini(struct irq_sim *sim)
> > +void irq_sim_free(struct irq_sim *sim)
> >  {
> >  	irq_work_sync(&sim->work_ctx.work);
> >  	bitmap_free(sim->work_ctx.pending);
> >  	irq_free_descs(sim->irq_base, sim->irq_count);
> >  	kfree(sim->irqs);
> > +	kfree(sim);
> >  }
> > -EXPORT_SYMBOL_GPL(irq_sim_fini);
> > +EXPORT_SYMBOL_GPL(irq_sim_free);
> >  
> >  static void devm_irq_sim_release(struct device *dev, void *res)
> >  {
> >  	struct irq_sim_devres *this = res;
> >  
> > -	irq_sim_fini(this->sim);
> > +	irq_sim_free(this->sim);
> >  }
> >  
> >  /**
> > - * irq_sim_init - Initialize the interrupt simulator for a managed device.
> > + * devm_irq_sim_new - Create a new interrupt simulator for a managed device.
> >   *
> >   * @dev:        Device to initialize the simulator object for.
> > - * @sim:        The interrupt simulator object to initialize.
> >   * @num_irqs:   Number of interrupts to allocate
> >   *
> > - * On success: return the base of the allocated interrupt range.
> > - * On failure: a negative errno.
> > + * On success: return a new irq_sim object.
> > + * On failure: a negative errno wrapped with ERR_PTR().
> >   */
> > -int devm_irq_sim_init(struct device *dev, struct irq_sim *sim,
> > -		      unsigned int num_irqs)
> > +struct irq_sim *devm_irq_sim_new(struct device *dev, unsigned int num_irqs)
> >  {
> >  	struct irq_sim_devres *dr;
> > -	int rv;
> >  
> >  	dr = devres_alloc(devm_irq_sim_release, sizeof(*dr), GFP_KERNEL);
> >  	if (!dr)
> > -		return -ENOMEM;
> > +		return ERR_PTR(-ENOMEM);
> >  
> > -	rv = irq_sim_init(sim, num_irqs);
> > -	if (rv < 0) {
> > +	dr->sim = irq_sim_new(num_irqs);
> > +	if (IS_ERR(dr->sim)) {
> >  		devres_free(dr);
> > -		return rv;
> > +		return dr->sim;
> >  	}
> >  
> > -	dr->sim = sim;
> >  	devres_add(dev, dr);
> > -
> > -	return rv;
> > +	return dr->sim;
> >  }
> > -EXPORT_SYMBOL_GPL(devm_irq_sim_init);
> > +EXPORT_SYMBOL_GPL(devm_irq_sim_new);
> >  
> >  /**
> >   * irq_sim_fire - Enqueue an interrupt.  
>