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Subject[PATCH v4 1/5] rtc: sysfs: facilitate attribute add to rtc device
Date
From: Denis Osterland <Denis.Osterland@diehl.com>

This patches addresses following problem:
rtc_allocate_device
devm_device_add_group <-- kernel oops / null pointer, because
sysfs entry does not yet exist
rtc_register_device
rc = devm_device_add_group
if (rc)
return rc; <-- forbidden to return error code
after device register

In case groups were not yet registered (kobj.state_in_sysfs == 0)
rtc_add_group just addes given group to dev.groups,
otherwise it uses devm_device_add_group.

Signed-off-by: Denis Osterland <Denis.Osterland@diehl.com>
---
drivers/rtc/rtc-core.h | 6 ++++++
drivers/rtc/rtc-sysfs.c | 39 +++++++++++++++++++++++++++++++++++++++
2 files changed, 45 insertions(+)

diff --git a/drivers/rtc/rtc-core.h b/drivers/rtc/rtc-core.h
index 0abf98983e13..81d1c3ce7a96 100644
--- a/drivers/rtc/rtc-core.h
+++ b/drivers/rtc/rtc-core.h
@@ -40,9 +40,15 @@ static inline void rtc_proc_del_device(struct rtc_device *rtc)

#ifdef CONFIG_RTC_INTF_SYSFS
const struct attribute_group **rtc_get_dev_attribute_groups(void);
+int rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp);
#else
static inline const struct attribute_group **rtc_get_dev_attribute_groups(void)
{
return NULL;
}
+static inline
+int rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp)
+{
+ return 0;
+}
#endif
diff --git a/drivers/rtc/rtc-sysfs.c b/drivers/rtc/rtc-sysfs.c
index 454da38c6012..9a177b8f761b 100644
--- a/drivers/rtc/rtc-sysfs.c
+++ b/drivers/rtc/rtc-sysfs.c
@@ -317,3 +317,42 @@ const struct attribute_group **rtc_get_dev_attribute_groups(void)
{
return rtc_attr_groups;
}
+
+static size_t rtc_group_count(struct rtc_device *rtc)
+{
+ const struct attribute_group **groups = rtc->dev.groups;
+ size_t cnt = 0;
+
+ if (groups)
+ for (; *groups; groups++)
+ cnt++;
+
+ return cnt;
+}
+
+static inline int
+__rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp)
+{
+ size_t cnt = rtc_group_count(rtc);
+ const struct attribute_group **groups, **old;
+
+ groups = devm_kzalloc(&rtc->dev, (cnt+2)*sizeof(*groups), GFP_KERNEL);
+ if (IS_ERR_OR_NULL(groups))
+ return PTR_ERR(groups);
+ memcpy(groups, rtc->dev.groups, cnt*sizeof(*groups));
+ groups[cnt] = grp;
+
+ old = rtc->dev.groups;
+ rtc->dev.groups = groups;
+ if (old != rtc_attr_groups)
+ devm_kfree(&rtc->dev, old);
+
+ return 0;
+}
+
+int rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp)
+{
+ return rtc->dev.kobj.state_in_sysfs ?
+ devm_device_add_group(&rtc->dev, grp) :
+ __rtc_add_group(rtc, grp);
+}
--
2.18.0


Diehl Connectivity Solutions GmbH
Geschäftsführung: Horst Leonberger
Sitz der Gesellschaft: Nürnberg - Registergericht: Amtsgericht
Nürnberg: HRB 32315
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