[PATCH v3 2/4] powerpc/fadump: reorganize /sys/kernel/fadump_* sysfs files

From: Sourabh Jain
Date: Sat Nov 09 2019 - 07:24:09 EST

As the number of FADump sysfs files increases it is hard to manage all of
them inside /sys/kernel directory. It's better to have all the FADump
related sysfs files in a dedicated directory /sys/kernel/fadump. But in
order to maintain the backward compatibility the /sys/kernel/fadump_*
sysfs files are replicated inside /sys/kernel/fadump/ and eventually get
removed in future.

As the FADump sysfs files are now part of dedicated directory there is no
need to prefix their name with fadump_, hence sysfs file names are also
updated. For example fadump_enabled sysfs file is now referred as enabled.

Also consolidate ABI documentation for all the FADump sysfs files in a
single file Documentation/ABI/testing/sysfs-kernel-fadump.

Signed-off-by: Sourabh Jain <sourabhjain@xxxxxxxxxxxxx>
---
Documentation/ABI/testing/sysfs-kernel-fadump | 41 +++++++++++++++++++
arch/powerpc/kernel/fadump.c | 38 +++++++++++++++++
arch/powerpc/platforms/powernv/opal-core.c | 10 +++--
3 files changed, 86 insertions(+), 3 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-kernel-fadump

diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump b/Documentation/ABI/testing/sysfs-kernel-fadump
new file mode 100644
index 000000000000..a77f1a5ba389
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-fadump
@@ -0,0 +1,41 @@
+What: /sys/kernel/fadump/*
+Date: Nov 2019
+Contact: linuxppc-dev@xxxxxxxxxxxxxxxx
+Description:
+ The /sys/kernel/fadump/* is a collection of FADump sysfs
+ file provide information about the configuration status
+ of Firmware Assisted Dump (FADump).
+
+What: /sys/kernel/fadump/enabled
+Date: Nov 2019
+Contact: linuxppc-dev@xxxxxxxxxxxxxxxx
+Description: read only
+ Primarily used to identify whether the FADump is enabled in
+ the kernel or not.
+User: Kdump service
+
+What: /sys/kernel/fadump/registered
+Date: Nov 2019
+Contact: linuxppc-dev@xxxxxxxxxxxxxxxx
+Description: read/write
+ Helps to control the dump collect feature from userspace.
+ Setting 1 to this file enables the system to collect the
+ dump and 0 to disable it.
+User: Kdump service
+
+What: /sys/kernel/fadump/release_mem
+Date: Nov 2019
+Contact: linuxppc-dev@xxxxxxxxxxxxxxxx
+Description: write only
+ This is a special sysfs file and only available when
+ the system is booted to capture the vmcore using FADump.
+ It is used to release the memory reserved by FADump to
+ save the crash dump.
+
+What: /sys/kernel/fadump/release_opalcore
+Date: Nov 2019
+Contact: linuxppc-dev@xxxxxxxxxxxxxxxx
+Description: write only
+ The sysfs file is available when the system is booted to
+ collect the dump on OPAL based machine. It used to release
+ the memory used to collect the opalcore.
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index ed59855430b9..a9591def0c84 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -1418,6 +1418,9 @@ static int fadump_region_show(struct seq_file *m, void *private)
return 0;
}

+struct kobject *fadump_kobj;
+EXPORT_SYMBOL_GPL(fadump_kobj);
+
static struct kobj_attribute fadump_release_attr = __ATTR(fadump_release_mem,
0200, NULL,
fadump_release_memory_store);
@@ -1428,6 +1431,16 @@ static struct kobj_attribute fadump_register_attr = __ATTR(fadump_registered,
0644, fadump_register_show,
fadump_register_store);

+static struct kobj_attribute release_attr = __ATTR(release_mem,
+ 0200, NULL,
+ fadump_release_memory_store);
+static struct kobj_attribute enable_attr = __ATTR(enabled,
+ 0444, fadump_enabled_show,
+ NULL);
+static struct kobj_attribute register_attr = __ATTR(registered,
+ 0644, fadump_register_show,
+ fadump_register_store);
+
DEFINE_SHOW_ATTRIBUTE(fadump_region);

static void fadump_init_files(void)
@@ -1435,6 +1448,11 @@ static void fadump_init_files(void)
struct dentry *debugfs_file;
int rc = 0;

+ fadump_kobj = kobject_create_and_add("fadump", kernel_kobj);
+ if (!fadump_kobj) {
+ pr_err("failed to create fadump kobject\n");
+ return;
+ }
rc = sysfs_create_file(kernel_kobj, &fadump_attr.attr);
if (rc)
printk(KERN_ERR "fadump: unable to create sysfs file"
@@ -1458,6 +1476,26 @@ static void fadump_init_files(void)
printk(KERN_ERR "fadump: unable to create sysfs file"
" fadump_release_mem (%d)\n", rc);
}
+ /* Replicating the following sysfs attributes under FADump kobject.
+ *
+ * - fadump_enabled -> enabled
+ * - fadump_registered -> registered
+ * - fadump_release_mem -> release_mem
+ */
+ rc = sysfs_create_file(fadump_kobj, &enable_attr.attr);
+ if (rc)
+ pr_err("unable to create enabled sysfs file (%d)\n",
+ rc);
+ rc = sysfs_create_file(fadump_kobj, &register_attr.attr);
+ if (rc)
+ pr_err("unable to create registered sysfs file (%d)\n",
+ rc);
+ if (fw_dump.dump_active) {
+ rc = sysfs_create_file(fadump_kobj, &release_attr.attr);
+ if (rc)
+ pr_err("unable to create release_mem sysfs file (%d)\n",
+ rc);
+ }
return;
}

diff --git a/arch/powerpc/platforms/powernv/opal-core.c b/arch/powerpc/platforms/powernv/opal-core.c
index ed895d82c048..b001e2242909 100644
--- a/arch/powerpc/platforms/powernv/opal-core.c
+++ b/arch/powerpc/platforms/powernv/opal-core.c
@@ -589,7 +589,7 @@ static ssize_t fadump_release_opalcore_store(struct kobject *kobj,
return count;
}

-static struct kobj_attribute opalcore_rel_attr = __ATTR(fadump_release_opalcore,
+static struct kobj_attribute opalcore_rel_attr = __ATTR(release_opalcore,
0200, NULL,
fadump_release_opalcore_store);

@@ -625,9 +625,13 @@ static int __init opalcore_init(void)
return rc;
}

- rc = sysfs_create_file(kernel_kobj, &opalcore_rel_attr.attr);
+ /*
+ * Originally fadump_release_opalcore sysfs was part of kernel_kobj
+ * later moved to fadump_kobj and renamed to release_opalcore.
+ */
+ rc = sysfs_create_file(fadump_kobj, &opalcore_rel_attr.attr);
if (rc) {
- pr_warn("unable to create sysfs file fadump_release_opalcore (%d)\n",
+ pr_warn("unable to create sysfs file release_opalcore (%d)\n",
rc);
}

--
2.17.2