Messages in this thread | | | Date | Fri, 2 Oct 2020 14:46:16 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH 1/2] pwm: sysfs: Set class on pwm devices |
| |
On Fri, Oct 02, 2020 at 02:30:47PM +0200, poeschel@lemonage.de wrote: > From: Lars Poeschel <poeschel@lemonage.de> > > This adds a class to exported pwm devices. > Exporting a pwm through sysfs did not yield udev events. The > dev_uevent_filter function does filter-out devices without a bus or > class. > This was already addressed in commit > commit 7e5d1fd75c3d ("pwm: Set class for exported channels in sysfs") > but this did cause problems and the commit got reverted with > commit c289d6625237 ("Revert "pwm: Set class for exported channels in > sysfs"") > Problem with the previous approach was, that there is a clash if we have > multiple pwmchips: > echo 0 > pwmchip0/export > echo 0 > pwmchip1/export > would both export /sys/class/pwm/pwm0 . > > Now this patch changes the sysfs interface. We do include the pwmchip > number into the pwm directory that gets exported. > With the example above we get: > /sys/class/pwm/pwm-0-0 > /sys/class/pwm/pwm-1-0 > We maintain ABI backward compatibility through symlinks. > /sys/class/pwm/pwmchip0/pwm0 > /sys/class/pwm/pwmchip1/pwm0 > are now symbolic links to the new names. > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Signed-off-by: Lars Poeschel <poeschel@lemonage.de> > --- > drivers/pwm/sysfs.c | 57 +++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 47 insertions(+), 10 deletions(-) > > diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c > index 449dbc0f49ed..c708da17a857 100644 > --- a/drivers/pwm/sysfs.c > +++ b/drivers/pwm/sysfs.c > @@ -240,8 +240,10 @@ static void pwm_export_release(struct device *child) > > static int pwm_export_child(struct device *parent, struct pwm_device *pwm) > { > + struct pwm_chip *chip = dev_get_drvdata(parent); > struct pwm_export *export; > char *pwm_prop[2]; > + char *link_name; > int ret; > > if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags)) > @@ -256,25 +258,39 @@ static int pwm_export_child(struct device *parent, struct pwm_device *pwm) > export->pwm = pwm; > mutex_init(&export->lock); > > + export->child.class = parent->class; > export->child.release = pwm_export_release; > export->child.parent = parent; > export->child.devt = MKDEV(0, 0); > export->child.groups = pwm_groups; > - dev_set_name(&export->child, "pwm%u", pwm->hwpwm); > + dev_set_name(&export->child, "pwm-%u-%u", chip->base, pwm->hwpwm); > > ret = device_register(&export->child); > - if (ret) { > - clear_bit(PWMF_EXPORTED, &pwm->flags); > - put_device(&export->child); > - export = NULL; > - return ret; > + if (ret) > + goto error; > + > + link_name = kasprintf(GFP_KERNEL, "pwm%u", pwm->hwpwm); > + if (link_name == NULL) { > + ret = -ENOMEM; > + goto dev_unregister; > } > - pwm_prop[0] = kasprintf(GFP_KERNEL, "EXPORT=pwm%u", pwm->hwpwm); > + > + pwm_prop[0] = kasprintf(GFP_KERNEL, "EXPORT=%s", > + export->child.kobj.name); > pwm_prop[1] = NULL; > kobject_uevent_env(&parent->kobj, KOBJ_CHANGE, pwm_prop);
Do you still need to do this by hand? Why can't this uevent field belong to the class and have it create this for you automatically when the device is added?
> kfree(pwm_prop[0]); > > - return 0; > + ret = sysfs_create_link(&parent->kobj, &export->child.kobj, link_name);
You create the link _after_ you told userspace it was there, you raced and lost :(
> + return ret; > + > +dev_unregister: > + device_unregister(&export->child); > +error: > + clear_bit(PWMF_EXPORTED, &pwm->flags); > + put_device(&export->child); > + export = NULL; > + return ret; > } > > static int pwm_unexport_match(struct device *child, void *data) > @@ -286,6 +302,7 @@ static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm) > { > struct device *child; > char *pwm_prop[2]; > + char *link_name; > > if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags)) > return -ENODEV; > @@ -294,7 +311,11 @@ static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm) > if (!child) > return -ENODEV; > > - pwm_prop[0] = kasprintf(GFP_KERNEL, "UNEXPORT=pwm%u", pwm->hwpwm); > + link_name = kasprintf(GFP_KERNEL, "pwm%u", pwm->hwpwm); > + if (link_name) > + sysfs_delete_link(&parent->kobj, &child->kobj, link_name); > + > + pwm_prop[0] = kasprintf(GFP_KERNEL, "UNEXPORT=%s", child->kobj.name); > pwm_prop[1] = NULL; > kobject_uevent_env(&parent->kobj, KOBJ_CHANGE, pwm_prop);
Same uevent question here.
Otherwise, this looks good, nice work in figuring out the is_visable stuff and everything.
thanks,
greg k-h
| |