Re: [PATCH v4 6/6] powerpc/fadump: sysfs for fadump memory reservation

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

On Fri, Dec 06, 2019 at 05:54:34PM +0530, Sourabh Jain wrote:

quoted

Add a sys interface to allow querying the memory reserved by FADump for
saving the crash dump.

Also added Documentation/ABI for the new sysfs file.

Signed-off-by: Sourabh Jain <redacted>
---
 Documentation/ABI/testing/sysfs-kernel-fadump    |  7 +++++++
 Documentation/powerpc/firmware-assisted-dump.rst |  5 +++++
 arch/powerpc/kernel/fadump.c                     | 15 +++++++++++++++
 3 files changed, 27 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump b/Documentation/ABI/testing/sysfs-kernel-fadump
index 5d988b919e81..8f7a64a81783 100644
--- a/Documentation/ABI/testing/sysfs-kernel-fadump
+++ b/Documentation/ABI/testing/sysfs-kernel-fadump

@@ -31,3 +31,10 @@ Description:	write only
 		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/mem_reserved
+Date:		Dec 2019
+Contact:	linuxppc-dev@lists.ozlabs.org
+Description:	read only
+		Provide information about the amount of memory reserved by
+		FADump to save the crash dump in bytes.

diff --git a/Documentation/powerpc/firmware-assisted-dump.rst b/Documentation/powerpc/firmware-assisted-dump.rst
index 365c10209ef3..04993eaf3113 100644
--- a/Documentation/powerpc/firmware-assisted-dump.rst
+++ b/Documentation/powerpc/firmware-assisted-dump.rst

@@ -268,6 +268,11 @@ Here is the list of files under kernel sysfs:
     be handled and vmcore will not be captured. This interface can be
     easily integrated with kdump service start/stop.
 
+ /sys/kernel/fadump/mem_reserved
+
+   This is used to display the memory reserved by FADump for saving the
+   crash dump.
+
  /sys/kernel/fadump_release_mem
     This file is available only when FADump is active during
     second kernel. This is used to release the reserved memory

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 41a3cda81791..b2af51b7c750 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c

@@ -1357,6 +1357,13 @@ static ssize_t fadump_enabled_show(struct kobject *kobj,
 	return sprintf(buf, "%d\n", fw_dump.fadump_enabled);
 }
 
+static ssize_t fadump_mem_reserved_show(struct kobject *kobj,
+					struct kobj_attribute *attr,
+					char *buf)
+{
+	return sprintf(buf, "%ld\n", fw_dump.reserve_dump_area_size);
+}
+
 static ssize_t fadump_register_show(struct kobject *kobj,
 					struct kobj_attribute *attr,
 					char *buf)

@@ -1430,6 +1437,10 @@ static struct kobj_attribute enable_attr = __ATTR(enabled,
 static struct kobj_attribute register_attr = __ATTR(registered,
 						0644, fadump_register_show,
 						fadump_register_store);
+static struct kobj_attribute mem_reserved_attr = __ATTR(mem_reserved,
+						0444, fadump_mem_reserved_show,
+						NULL);

__ATTRI_RO()?

quoted

+
 
 DEFINE_SHOW_ATTRIBUTE(fadump_region);
 

@@ -1464,6 +1475,10 @@ static void fadump_init_files(void)
 			pr_err("unable to create release_mem sysfs file (%d)\n",
 			       rc);
 	}
+	rc = sysfs_create_file(fadump_kobj, &mem_reserved_attr.attr);
+	if (rc)
+		pr_err("unable to create mem_reserved sysfs file (%d)\n",
+		       rc);

Again, put it in an attribute group, that would have only required one
line, and not this mess of not cleaning up if something went wrong.

Will make the changes accordingly.


Thanks,
Sourabh Jain