Re: [PATCH v4 4/6] powerpc/powernv: move core and fadump_release_opalcore under new kobject

On 12/6/19 6:18 PM, Greg KH wrote:

On Fri, Dec 06, 2019 at 05:54:32PM +0530, Sourabh Jain wrote:

quoted

The /sys/firmware/opal/core and /sys/kernel/fadump_release_opalcore sysfs
files are used to export and release the OPAL memory on PowerNV platform.
let's organize them into a new kobject under /sys/firmware/opal/mpipl/
directory.

A symlink is added to maintain the backward compatibility for
/sys/firmware/opal/core sysfs file.

Signed-off-by: Sourabh Jain <redacted>
---
 .../sysfs-kernel-fadump_release_opalcore      |  2 ++
 .../powerpc/firmware-assisted-dump.rst        | 15 +++++----
 arch/powerpc/platforms/powernv/opal-core.c    | 31 ++++++++++++++-----
 3 files changed, 34 insertions(+), 14 deletions(-)
 rename Documentation/ABI/{testing => removed}/sysfs-kernel-fadump_release_opalcore (82%)

diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump_release_opalcore b/Documentation/ABI/removed/sysfs-kernel-fadump_release_opalcore
similarity index 82%
rename from Documentation/ABI/testing/sysfs-kernel-fadump_release_opalcore
rename to Documentation/ABI/removed/sysfs-kernel-fadump_release_opalcore
index 53313c1d4e7a..a8d46cd0f4e6 100644
--- a/Documentation/ABI/testing/sysfs-kernel-fadump_release_opalcore
+++ b/Documentation/ABI/removed/sysfs-kernel-fadump_release_opalcore

@@ -1,3 +1,5 @@
+This ABI is moved to /sys/firmware/opal/mpipl/release_core.
+
 What:		/sys/kernel/fadump_release_opalcore
 Date:		Sep 2019
 Contact:	linuxppc-dev@lists.ozlabs.org

diff --git a/Documentation/powerpc/firmware-assisted-dump.rst b/Documentation/powerpc/firmware-assisted-dump.rst
index 0455a78486d5..345a3405206e 100644
--- a/Documentation/powerpc/firmware-assisted-dump.rst
+++ b/Documentation/powerpc/firmware-assisted-dump.rst

@@ -112,13 +112,13 @@ to ensure that crash data is preserved to process later.
 
 -- On OPAL based machines (PowerNV), if the kernel is build with
    CONFIG_OPAL_CORE=y, OPAL memory at the time of crash is also
-   exported as /sys/firmware/opal/core file. This procfs file is
+   exported as /sys/firmware/opal/mpipl/core file. This procfs file is
    helpful in debugging OPAL crashes with GDB. The kernel memory
    used for exporting this procfs file can be released by echo'ing
-   '1' to /sys/kernel/fadump_release_opalcore node.
+   '1' to /sys/firmware/opal/mpipl/release_core node.
 
    e.g.
-     # echo 1 > /sys/kernel/fadump_release_opalcore
+     # echo 1 > /sys/firmware/opal/mpipl/release_core
 
 Implementation details:
 -----------------------

@@ -283,14 +283,17 @@ Here is the list of files under kernel sysfs:
     enhanced to use this interface to release the memory reserved for
     dump and continue without 2nd reboot.
 
- /sys/kernel/fadump_release_opalcore
+Note: /sys/kernel/fadump_release_opalcore sysfs has moved to
+      /sys/firmware/opal/mpipl/release_core
+
+ /sys/firmware/opal/mpipl/release_core
 
     This file is available only on OPAL based machines when FADump is
     active during capture kernel. This is used to release the memory
-    used by the kernel to export /sys/firmware/opal/core file. To
+    used by the kernel to export /sys/firmware/opal/mpipl/core file. To
     release this memory, echo '1' to it:
 
-    echo 1  > /sys/kernel/fadump_release_opalcore
+    echo 1  > /sys/firmware/opal/mpipl/release_core
 
 Here is the list of files under powerpc debugfs:
 (Assuming debugfs is mounted on /sys/kernel/debug directory.)

diff --git a/arch/powerpc/platforms/powernv/opal-core.c b/arch/powerpc/platforms/powernv/opal-core.c
index ed895d82c048..7fcc092d065e 100644
--- a/arch/powerpc/platforms/powernv/opal-core.c
+++ b/arch/powerpc/platforms/powernv/opal-core.c

@@ -589,7 +589,8 @@ static ssize_t fadump_release_opalcore_store(struct kobject *kobj,
 	return count;
 }
 
-static struct kobj_attribute opalcore_rel_attr = __ATTR(fadump_release_opalcore,
+struct kobject *mpipl_kobj;
+static struct kobj_attribute opalcore_rel_attr = __ATTR(release_core,
 						0200, NULL,
 						fadump_release_opalcore_store);

__ATTR_WO()?

Thanks :)

quoted

@@ -609,7 +610,7 @@ static int __init opalcore_init(void)
 	 * then capture the dump.
 	 */
 	if (!(is_opalcore_usable())) {
-		pr_err("Failed to export /sys/firmware/opal/core\n");
+		pr_err("Failed to export /sys/firmware/opal/mpipl/core\n");
 		opalcore_cleanup();
 		return rc;
 	}

@@ -617,18 +618,32 @@ static int __init opalcore_init(void)
 	/* Set OPAL core file size */
 	opal_core_attr.size = oc_conf->opalcore_size;
 
+	mpipl_kobj = kobject_create_and_add("mpipl", opal_kobj);
+	if (!mpipl_kobj) {
+		pr_err("unable to create mpipl kobject\n");
+		return -ENOMEM;
+	}
+
 	/* Export OPAL core sysfs file */
-	rc = sysfs_create_bin_file(opal_kobj, &opal_core_attr);
+	rc = sysfs_create_bin_file(mpipl_kobj, &opal_core_attr);

Again, create an attribute group and add everything all at once, makes
it much simpler and your error cleanup logic will actually work :)

Agree.

Thanks,
Sourabh Jain