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

Sourabh Jain
2019-12-06T19:16:33Z

On 12/6/19 6:18 PM, Greg KH wrote:
> On Fri, Dec 06, 2019 at 05:54:32PM +0530, Sourabh Jain wrote:
>> 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 <sourabhjain@linux.ibm.com>
>> ---
>> .../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 :)
>
>>
>> @@ -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