[PATCH v2] driver: sysfs: Add compatibility for default_groups

[Ralf Ramsauer]

Since Linux commit cdb4f26a63c3 ("kobject: kobj_type: remove
default_attrs"), the deprecated kobj member default_attrs is gone. It is
replaced by default_groups.

Add a compatibility layer to support older, as well as latest kernel
versions.

Signed-off-by: Ralf Ramsauer <ralf.ramsa...@oth-regensburg.de>
---

Note: only compile-time tested!

 driver/sysfs.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/driver/sysfs.c b/driver/sysfs.c
index a604afa4..a5a02831 100644
--- a/driver/sysfs.c
+++ b/driver/sysfs.c
@@ -59,6 +59,14 @@ static const struct sysfs_ops cell_sysfs_ops = {
 };
 #define kobj_sysfs_ops cell_sysfs_ops
 #endif /* < 3.14 */
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5,2,0)
+#define COMPAT_ATTRIBUTE_GROUPS(x)     /* not used */
+#define DEFAULT_GROUPS(x)              .default_attrs = x##_attrs
+#else
+#define COMPAT_ATTRIBUTE_GROUPS(x)     ATTRIBUTE_GROUPS(x)
+#define DEFAULT_GROUPS(x)              .default_groups = x##_groups
+#endif /* < 5.2 */
 /* End of compatibility section - remove as version become obsolete */
 
 static struct kobject *cells_dir;
@@ -180,10 +188,11 @@ static struct attribute *cell_stats_attrs[] = {
 #endif
        NULL
 };
+COMPAT_ATTRIBUTE_GROUPS(cell_stats);
 
 static struct kobj_type cell_stats_type = {
        .sysfs_ops = &kobj_sysfs_ops,
-       .default_attrs = cell_stats_attrs,
+       DEFAULT_GROUPS(cell_stats),
 };
 
 static struct attribute *cpu_stats_attrs[] = {
@@ -212,10 +221,11 @@ static struct attribute *cpu_stats_attrs[] = {
 #endif
        NULL
 };
+COMPAT_ATTRIBUTE_GROUPS(cpu_stats);
 
 static struct kobj_type cell_cpu_type = {
        .sysfs_ops = &kobj_sysfs_ops,
-       .default_attrs = cpu_stats_attrs,
+       DEFAULT_GROUPS(cpu_stats),
 };
 
 static int print_cpumask(char *buf, size_t size, cpumask_t *mask, bool as_list)
@@ -342,11 +352,12 @@ static struct attribute *cell_attrs[] = {
        &cell_cpus_failed_list_attr.attr,
        NULL,
 };
+COMPAT_ATTRIBUTE_GROUPS(cell);
 
 static struct kobj_type cell_type = {
        .release = jailhouse_cell_kobj_release,
        .sysfs_ops = &kobj_sysfs_ops,
-       .default_attrs = cell_attrs,
+       DEFAULT_GROUPS(cell),
 };
 
 static struct cell_cpu *find_cell_cpu(struct cell *cell, unsigned int cpu)
-- 
2.36.0

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