* [PATCH v5 1/5] nvmem: fix memory leak in error path
2020-02-21 15:48 [PATCH v5 0/5] nvmem/gpio: fix resource management Bartosz Golaszewski
@ 2020-02-21 15:48 ` Bartosz Golaszewski
2020-02-21 16:42 ` Srinivas Kandagatla
2020-02-21 15:48 ` [PATCH v5 2/5] gpiolib: provide VALIDATE_DESC_PTR() macro Bartosz Golaszewski
` (3 subsequent siblings)
4 siblings, 1 reply; 10+ messages in thread
From: Bartosz Golaszewski @ 2020-02-21 15:48 UTC (permalink / raw)
To: Linus Walleij, Srinivas Kandagatla, Khouloud Touil, Geert Uytterhoeven
Cc: linux-gpio, linux-kernel, Bartosz Golaszewski
From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
We need to free the ida mapping and nvmem struct if the write-protect
GPIO lookup fails.
Fixes: 2a127da461a9 ("nvmem: add support for the write-protect pin")
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
drivers/nvmem/core.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 503da67dde06..2758d90d63b7 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -353,8 +353,12 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
else
nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
GPIOD_OUT_HIGH);
- if (IS_ERR(nvmem->wp_gpio))
- return ERR_CAST(nvmem->wp_gpio);
+ if (IS_ERR(nvmem->wp_gpio)) {
+ ida_simple_remove(&nvmem_ida, nvmem->id);
+ rval = PTR_ERR(nvmem->wp_gpio);
+ kfree(nvmem);
+ return ERR_PTR(rval);
+ }
kref_init(&nvmem->refcnt);
INIT_LIST_HEAD(&nvmem->cells);
--
2.25.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH v5 1/5] nvmem: fix memory leak in error path
2020-02-21 15:48 ` [PATCH v5 1/5] nvmem: fix memory leak in error path Bartosz Golaszewski
@ 2020-02-21 16:42 ` Srinivas Kandagatla
0 siblings, 0 replies; 10+ messages in thread
From: Srinivas Kandagatla @ 2020-02-21 16:42 UTC (permalink / raw)
To: Bartosz Golaszewski, Linus Walleij, Khouloud Touil, Geert Uytterhoeven
Cc: linux-gpio, linux-kernel, Bartosz Golaszewski
On 21/02/2020 15:48, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> We need to free the ida mapping and nvmem struct if the write-protect
> GPIO lookup fails.
>
> Fixes: 2a127da461a9 ("nvmem: add support for the write-protect pin")
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Applied this and 5/5
Thanks,
srini
> ---
> drivers/nvmem/core.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> index 503da67dde06..2758d90d63b7 100644
> --- a/drivers/nvmem/core.c
> +++ b/drivers/nvmem/core.c
> @@ -353,8 +353,12 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
> else
> nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
> GPIOD_OUT_HIGH);
> - if (IS_ERR(nvmem->wp_gpio))
> - return ERR_CAST(nvmem->wp_gpio);
> + if (IS_ERR(nvmem->wp_gpio)) {
> + ida_simple_remove(&nvmem_ida, nvmem->id);
> + rval = PTR_ERR(nvmem->wp_gpio);
> + kfree(nvmem);
> + return ERR_PTR(rval);
> + }
>
> kref_init(&nvmem->refcnt);
> INIT_LIST_HEAD(&nvmem->cells);
>
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v5 2/5] gpiolib: provide VALIDATE_DESC_PTR() macro
2020-02-21 15:48 [PATCH v5 0/5] nvmem/gpio: fix resource management Bartosz Golaszewski
2020-02-21 15:48 ` [PATCH v5 1/5] nvmem: fix memory leak in error path Bartosz Golaszewski
@ 2020-02-21 15:48 ` Bartosz Golaszewski
2020-02-28 22:15 ` Linus Walleij
2020-02-21 15:48 ` [PATCH v5 3/5] gpiolib: use kref in gpio_desc Bartosz Golaszewski
` (2 subsequent siblings)
4 siblings, 1 reply; 10+ messages in thread
From: Bartosz Golaszewski @ 2020-02-21 15:48 UTC (permalink / raw)
To: Linus Walleij, Srinivas Kandagatla, Khouloud Touil, Geert Uytterhoeven
Cc: linux-gpio, linux-kernel, Bartosz Golaszewski
From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
We're about to add a public GPIO function that takes a descriptor as
argument and returns a pointer. Add a corresponding macro wrapping the
validate_desc() function that returns an ERR_PTR() on error.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
drivers/gpio/gpiolib.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 4d0106ceeba7..da8ffd40aa97 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2864,6 +2864,14 @@ static int validate_desc(const struct gpio_desc *desc, const char *func)
return; \
} while (0)
+#define VALIDATE_DESC_PTR(desc) do { \
+ int __valid = validate_desc(desc, __func__); \
+ if (__valid < 0) \
+ return ERR_PTR(__valid); \
+ if (__valid == 0) \
+ return NULL; \
+ } while (0)
+
int gpiod_request(struct gpio_desc *desc, const char *label)
{
int ret = -EPROBE_DEFER;
--
2.25.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH v5 2/5] gpiolib: provide VALIDATE_DESC_PTR() macro
2020-02-21 15:48 ` [PATCH v5 2/5] gpiolib: provide VALIDATE_DESC_PTR() macro Bartosz Golaszewski
@ 2020-02-28 22:15 ` Linus Walleij
0 siblings, 0 replies; 10+ messages in thread
From: Linus Walleij @ 2020-02-28 22:15 UTC (permalink / raw)
To: Bartosz Golaszewski
Cc: Srinivas Kandagatla, Khouloud Touil, Geert Uytterhoeven,
open list:GPIO SUBSYSTEM, linux-kernel, Bartosz Golaszewski
On Fri, Feb 21, 2020 at 4:48 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> We're about to add a public GPIO function that takes a descriptor as
> argument and returns a pointer. Add a corresponding macro wrapping the
> validate_desc() function that returns an ERR_PTR() on error.
>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
(I expect to get this back as a pull request or something later.)
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v5 3/5] gpiolib: use kref in gpio_desc
2020-02-21 15:48 [PATCH v5 0/5] nvmem/gpio: fix resource management Bartosz Golaszewski
2020-02-21 15:48 ` [PATCH v5 1/5] nvmem: fix memory leak in error path Bartosz Golaszewski
2020-02-21 15:48 ` [PATCH v5 2/5] gpiolib: provide VALIDATE_DESC_PTR() macro Bartosz Golaszewski
@ 2020-02-21 15:48 ` Bartosz Golaszewski
2020-02-28 22:32 ` Linus Walleij
2020-02-21 15:48 ` [PATCH v5 4/5] nvmem: increase the reference count of a gpio passed over config Bartosz Golaszewski
2020-02-21 15:48 ` [PATCH v5 5/5] nvmem: release the write-protect pin Bartosz Golaszewski
4 siblings, 1 reply; 10+ messages in thread
From: Bartosz Golaszewski @ 2020-02-21 15:48 UTC (permalink / raw)
To: Linus Walleij, Srinivas Kandagatla, Khouloud Touil, Geert Uytterhoeven
Cc: linux-gpio, linux-kernel, Bartosz Golaszewski
From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
GPIO descriptors are freed by consumers using gpiod_put(). The name of
this function suggests some reference counting is going on but it's not
true.
Use kref to actually introduce reference counting for gpio_desc objects.
Add a corresponding gpiod_get() helper for increasing the reference count.
This doesn't change anything for already existing (correct) drivers but
allows us to keep track of GPIO descs used by multiple users.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
drivers/gpio/gpiolib.c | 38 +++++++++++++++++++++++++++++++----
drivers/gpio/gpiolib.h | 1 +
include/linux/gpio/consumer.h | 1 +
3 files changed, 36 insertions(+), 4 deletions(-)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index da8ffd40aa97..a00e28ca8a49 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2798,6 +2798,8 @@ static int gpiod_request_commit(struct gpio_desc *desc, const char *label)
goto done;
}
+ kref_init(&desc->ref);
+
if (chip->request) {
/* chip->request may sleep */
spin_unlock_irqrestore(&gpio_lock, flags);
@@ -2941,6 +2943,13 @@ void gpiod_free(struct gpio_desc *desc)
}
}
+static void gpiod_free_kref(struct kref *ref)
+{
+ struct gpio_desc *desc = container_of(ref, struct gpio_desc, ref);
+
+ gpiod_free(desc);
+}
+
/**
* gpiochip_is_requested - return string iff signal was requested
* @chip: controller managing the signal
@@ -5075,18 +5084,39 @@ struct gpio_descs *__must_check gpiod_get_array_optional(struct device *dev,
EXPORT_SYMBOL_GPL(gpiod_get_array_optional);
/**
- * gpiod_put - dispose of a GPIO descriptor
- * @desc: GPIO descriptor to dispose of
+ * gpiod_put - decrease the reference count of a GPIO descriptor
+ * @desc: GPIO descriptor to unref
*
* No descriptor can be used after gpiod_put() has been called on it.
*/
void gpiod_put(struct gpio_desc *desc)
{
- if (desc)
- gpiod_free(desc);
+ VALIDATE_DESC_VOID(desc);
+
+ kref_put(&desc->ref, gpiod_free_kref);
}
EXPORT_SYMBOL_GPL(gpiod_put);
+/**
+ * gpiod_ref - increase the reference count of a GPIO descriptor
+ * @desc: GPIO descriptor to reference
+ *
+ * Returns the same gpio_desc after increasing the reference count.
+ */
+struct gpio_desc *gpiod_ref(struct gpio_desc *desc)
+{
+ VALIDATE_DESC_PTR(desc);
+
+ if (!test_bit(FLAG_REQUESTED, &desc->flags)) {
+ pr_warn("gpiolib: unable to increase the reference count of unrequested GPIO descriptor\n");
+ return desc;
+ }
+
+ kref_get(&desc->ref);
+ return desc;
+}
+EXPORT_SYMBOL_GPL(gpiod_ref);
+
/**
* gpiod_put_array - dispose of multiple GPIO descriptors
* @descs: struct gpio_descs containing an array of descriptors
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 3e0aab2945d8..51a92c43dd55 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -119,6 +119,7 @@ struct gpio_desc {
const char *label;
/* Name of the GPIO */
const char *name;
+ struct kref ref;
};
int gpiod_request(struct gpio_desc *desc, const char *label);
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index bf2d017dd7b7..c7b5fb3d9d64 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -81,6 +81,7 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
struct gpio_descs *__must_check gpiod_get_array_optional(struct device *dev,
const char *con_id,
enum gpiod_flags flags);
+struct gpio_desc *gpiod_ref(struct gpio_desc *desc);
void gpiod_put(struct gpio_desc *desc);
void gpiod_put_array(struct gpio_descs *descs);
--
2.25.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH v5 3/5] gpiolib: use kref in gpio_desc
2020-02-21 15:48 ` [PATCH v5 3/5] gpiolib: use kref in gpio_desc Bartosz Golaszewski
@ 2020-02-28 22:32 ` Linus Walleij
2020-02-29 20:15 ` Bartosz Golaszewski
0 siblings, 1 reply; 10+ messages in thread
From: Linus Walleij @ 2020-02-28 22:32 UTC (permalink / raw)
To: Bartosz Golaszewski
Cc: Srinivas Kandagatla, Khouloud Touil, Geert Uytterhoeven,
open list:GPIO SUBSYSTEM, linux-kernel, Bartosz Golaszewski
On Fri, Feb 21, 2020 at 4:48 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> GPIO descriptors are freed by consumers using gpiod_put(). The name of
> this function suggests some reference counting is going on but it's not
> true.
>
> Use kref to actually introduce reference counting for gpio_desc objects.
> Add a corresponding gpiod_get() helper for increasing the reference count.
>
> This doesn't change anything for already existing (correct) drivers but
> allows us to keep track of GPIO descs used by multiple users.
>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
I'm having some trouble figuring out if we might be reinventing
a wheel here.
A while back there was a proposed patch to add device links
between GPIO producers and consumers, so that a GPIO
chip won't be dropped while there are active consumers.
(I don't remember who sent the patch.)
We have a similar functionality in pin control if the
.link_consumers property is set on the pincontrol device.
I was thinking about making that compulsory at one point.
The device links use a kref already existing in struct
device and would in this case be the kref in the struct
device for the struct gpio_device.
So if that existed, gpiod_ref could just grab another
device_link_add().
Maybe we should just add device links between all
GPIO consumers (devices) and struct gpio_device:s
struct device and implement it like this so we don't
have to back out of this later?
C.f. commit
commit 036f394dd77f8117346874151793ec38967d843f
pinctrl: Enable device link creation for pin control
(...)
> @@ -81,6 +81,7 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
> struct gpio_descs *__must_check gpiod_get_array_optional(struct device *dev,
> const char *con_id,
> enum gpiod_flags flags);
> +struct gpio_desc *gpiod_ref(struct gpio_desc *desc);
> void gpiod_put(struct gpio_desc *desc);
> void gpiod_put_array(struct gpio_descs *descs);
You forgot to add a stub for the case where GPIOLIB is not
compiled in I think? (Lower in the same file.)
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v5 3/5] gpiolib: use kref in gpio_desc
2020-02-28 22:32 ` Linus Walleij
@ 2020-02-29 20:15 ` Bartosz Golaszewski
0 siblings, 0 replies; 10+ messages in thread
From: Bartosz Golaszewski @ 2020-02-29 20:15 UTC (permalink / raw)
To: Linus Walleij
Cc: Bartosz Golaszewski, Srinivas Kandagatla, Khouloud Touil,
Geert Uytterhoeven, open list:GPIO SUBSYSTEM, linux-kernel
pt., 28 lut 2020 o 23:33 Linus Walleij <linus.walleij@linaro.org> napisał(a):
>
> On Fri, Feb 21, 2020 at 4:48 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>
> > From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> >
> > GPIO descriptors are freed by consumers using gpiod_put(). The name of
> > this function suggests some reference counting is going on but it's not
> > true.
> >
> > Use kref to actually introduce reference counting for gpio_desc objects.
> > Add a corresponding gpiod_get() helper for increasing the reference count.
> >
> > This doesn't change anything for already existing (correct) drivers but
> > allows us to keep track of GPIO descs used by multiple users.
> >
> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> I'm having some trouble figuring out if we might be reinventing
> a wheel here.
>
> A while back there was a proposed patch to add device links
> between GPIO producers and consumers, so that a GPIO
> chip won't be dropped while there are active consumers.
>
> (I don't remember who sent the patch.)
>
> We have a similar functionality in pin control if the
> .link_consumers property is set on the pincontrol device.
> I was thinking about making that compulsory at one point.
>
> The device links use a kref already existing in struct
> device and would in this case be the kref in the struct
> device for the struct gpio_device.
>
> So if that existed, gpiod_ref could just grab another
> device_link_add().
>
I was always under the impression that device links are aimed mostly
at runtime PM.
> Maybe we should just add device links between all
> GPIO consumers (devices) and struct gpio_device:s
> struct device and implement it like this so we don't
> have to back out of this later?
>
> C.f. commit
> commit 036f394dd77f8117346874151793ec38967d843f
> pinctrl: Enable device link creation for pin control
>
Yes, definitely looks like it's done with PM in mind. Maybe we should
do what nvmem does? Define a struct device_type for GPIO chips with an
appropriate release() callback and use get_device() and put_device()?
Although nvmem seems to use kref for cells and device reference
counting somewhat separately - maybe that's something to address too.
> (...)
> > @@ -81,6 +81,7 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
> > struct gpio_descs *__must_check gpiod_get_array_optional(struct device *dev,
> > const char *con_id,
> > enum gpiod_flags flags);
> > +struct gpio_desc *gpiod_ref(struct gpio_desc *desc);
> > void gpiod_put(struct gpio_desc *desc);
> > void gpiod_put_array(struct gpio_descs *descs);
>
> You forgot to add a stub for the case where GPIOLIB is not
> compiled in I think? (Lower in the same file.)
>
> Yours,
> Linus Walleij
Yeah this is fixed in the next version (with a different subject since
it no longer concerns nvmem that much).
Bart
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v5 4/5] nvmem: increase the reference count of a gpio passed over config
2020-02-21 15:48 [PATCH v5 0/5] nvmem/gpio: fix resource management Bartosz Golaszewski
` (2 preceding siblings ...)
2020-02-21 15:48 ` [PATCH v5 3/5] gpiolib: use kref in gpio_desc Bartosz Golaszewski
@ 2020-02-21 15:48 ` Bartosz Golaszewski
2020-02-21 15:48 ` [PATCH v5 5/5] nvmem: release the write-protect pin Bartosz Golaszewski
4 siblings, 0 replies; 10+ messages in thread
From: Bartosz Golaszewski @ 2020-02-21 15:48 UTC (permalink / raw)
To: Linus Walleij, Srinivas Kandagatla, Khouloud Touil, Geert Uytterhoeven
Cc: linux-gpio, linux-kernel, Bartosz Golaszewski
From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
We can obtain the write-protect GPIO in nvmem_register() by requesting
it ourselves or by storing the gpio_desc passed in nvmem_config. In the
latter case we need to increase the reference count so that it gets
freed correctly.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
drivers/nvmem/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 2758d90d63b7..4a4ef2049022 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -349,7 +349,7 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
}
if (config->wp_gpio)
- nvmem->wp_gpio = config->wp_gpio;
+ nvmem->wp_gpio = gpiod_ref(config->wp_gpio);
else
nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
GPIOD_OUT_HIGH);
--
2.25.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH v5 5/5] nvmem: release the write-protect pin
2020-02-21 15:48 [PATCH v5 0/5] nvmem/gpio: fix resource management Bartosz Golaszewski
` (3 preceding siblings ...)
2020-02-21 15:48 ` [PATCH v5 4/5] nvmem: increase the reference count of a gpio passed over config Bartosz Golaszewski
@ 2020-02-21 15:48 ` Bartosz Golaszewski
4 siblings, 0 replies; 10+ messages in thread
From: Bartosz Golaszewski @ 2020-02-21 15:48 UTC (permalink / raw)
To: Linus Walleij, Srinivas Kandagatla, Khouloud Touil, Geert Uytterhoeven
Cc: linux-gpio, linux-kernel, Bartosz Golaszewski
From: Khouloud Touil <ktouil@baylibre.com>
Put the write-protect GPIO descriptor in nvmem_release() so that it can
be automatically released when the associated device's reference count
drops to 0.
Fixes: 2a127da461a9 ("nvmem: add support for the write-protect pin")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Khouloud Touil <ktouil@baylibre.com>
[Bartosz: tweak the commit message]
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
drivers/nvmem/core.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 4a4ef2049022..790ec9b5552e 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -72,6 +72,7 @@ static void nvmem_release(struct device *dev)
struct nvmem_device *nvmem = to_nvmem_device(dev);
ida_simple_remove(&nvmem_ida, nvmem->id);
+ gpiod_put(nvmem->wp_gpio);
kfree(nvmem);
}
--
2.25.0
^ permalink raw reply related [flat|nested] 10+ messages in thread