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SubjectRe: [PATCH v3 2/4] powerpc/fadump: reorganize /sys/kernel/fadump_* sysfs files
On Sat, Nov 09, 2019 at 05:53:37PM +0530, Sourabh Jain wrote:
> 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@linux.ibm.com>
> ---
> 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@lists.ozlabs.org
> +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@lists.ozlabs.org
> +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@lists.ozlabs.org
> +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@lists.ozlabs.org
> +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@lists.ozlabs.org
> +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;
> }
Hello,

wouldn't it make more sense to create the files in the new location and
add a symlink at the old location?

Also your error messages aren't really readeable. Without the fadump_
prefix it's not clear what's going on here. Perhaps quoting the file
name and saying fadump somewhere in the message would be useful.

Thanks

Michal

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