[PATCH v3 3/7] devcoredump: allow to create several coredump files in one device

From: Akinobu Mita
Date: Sun May 12 2019 - 11:56:32 EST

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The device coredump mechanism currently allows drivers to create only a
single coredump file. If there are several binary blobs to dump, we need
to define a binary format or conver to text format in order to put them
into a single coredump file.

This provides a new function that allows drivers to create several device
coredump files in one crashed device.

Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Cc: Keith Busch <keith.busch@xxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Sagi Grimberg <sagi@xxxxxxxxxxx>
Cc: Minwoo Im <minwoo.im.dev@xxxxxxxxx>
Cc: Kenneth Heitke <kenneth.heitke@xxxxxxxxx>
Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
---
* v3
- No change since v2

drivers/base/devcoredump.c | 155 ++++++++++++++++++++++++++++++--------------
include/linux/devcoredump.h | 33 ++++++++++
2 files changed, 139 insertions(+), 49 deletions(-)

diff --git a/drivers/base/devcoredump.c b/drivers/base/devcoredump.c
index e42d0b5..4dd6dba 100644
--- a/drivers/base/devcoredump.c
+++ b/drivers/base/devcoredump.c
@@ -25,16 +25,20 @@ static bool devcd_disabled;
/* if data isn't read by userspace after 5 minutes then delete it */
#define DEVCD_TIMEOUT (HZ * 60 * 5)

-struct devcd_entry {
- struct device devcd_dev;
- void *data;
- size_t datalen;
- struct module *owner;
+struct devcd_file {
+ struct bin_attribute bin_attr;
ssize_t (*read)(char *buffer, loff_t offset, size_t count,
void *data, size_t datalen);
void (*free)(void *data);
+};
+
+struct devcd_entry {
+ struct device devcd_dev;
+ struct module *owner;
struct delayed_work del_wk;
struct device *failing_dev;
+ int num_files;
+ struct devcd_file files[];
};

static struct devcd_entry *dev_to_devcd(struct device *dev)
@@ -45,8 +49,14 @@ static struct devcd_entry *dev_to_devcd(struct device *dev)
static void devcd_dev_release(struct device *dev)
{
struct devcd_entry *devcd = dev_to_devcd(dev);
+ int i;
+
+ for (i = 0; i < devcd->num_files; i++) {
+ struct devcd_file *file = &devcd->files[i];
+
+ file->free(file->bin_attr.private);
+ }

- devcd->free(devcd->data);
module_put(devcd->owner);

/*
@@ -64,9 +74,14 @@ static void devcd_dev_release(struct device *dev)
static void devcd_del(struct work_struct *wk)
{
struct devcd_entry *devcd;
+ int i;

devcd = container_of(wk, struct devcd_entry, del_wk.work);

+ for (i = 0; i < devcd->num_files; i++)
+ device_remove_bin_file(&devcd->devcd_dev,
+ &devcd->files[i].bin_attr);
+
device_del(&devcd->devcd_dev);
put_device(&devcd->devcd_dev);
}
@@ -75,10 +90,11 @@ static ssize_t devcd_data_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr,
char *buffer, loff_t offset, size_t count)
{
- struct device *dev = kobj_to_dev(kobj);
- struct devcd_entry *devcd = dev_to_devcd(dev);
+ struct devcd_file *file =
+ container_of(bin_attr, struct devcd_file, bin_attr);

- return devcd->read(buffer, offset, count, devcd->data, devcd->datalen);
+ return file->read(buffer, offset, count, bin_attr->private,
+ bin_attr->size);
}

static ssize_t devcd_data_write(struct file *filp, struct kobject *kobj,
@@ -93,25 +109,6 @@ static ssize_t devcd_data_write(struct file *filp, struct kobject *kobj,
return count;
}

-static struct bin_attribute devcd_attr_data = {
- .attr = { .name = "data", .mode = S_IRUSR | S_IWUSR, },
- .size = 0,
- .read = devcd_data_read,
- .write = devcd_data_write,
-};
-
-static struct bin_attribute *devcd_dev_bin_attrs[] = {
- &devcd_attr_data, NULL,
-};
-
-static const struct attribute_group devcd_dev_group = {
- .bin_attrs = devcd_dev_bin_attrs,
-};
-
-static const struct attribute_group *devcd_dev_groups[] = {
- &devcd_dev_group, NULL,
-};
-
static int devcd_free(struct device *dev, void *data)
{
struct devcd_entry *devcd = dev_to_devcd(dev);
@@ -157,7 +154,6 @@ static struct class devcd_class = {
.name = "devcoredump",
.owner = THIS_MODULE,
.dev_release = devcd_dev_release,
- .dev_groups = devcd_dev_groups,
.class_groups = devcd_class_groups,
};

@@ -234,30 +230,55 @@ static ssize_t devcd_read_from_sgtable(char *buffer, loff_t offset,
offset);
}

+static struct devcd_entry *devcd_alloc(struct dev_coredumpm_bulk_data *files,
+ int num_files, gfp_t gfp)
+{
+ struct devcd_entry *devcd;
+ int i;
+
+ devcd = kzalloc(struct_size(devcd, files, num_files), gfp);
+ if (!devcd)
+ return NULL;
+
+ devcd->num_files = num_files;
+
+ for (i = 0; i < devcd->num_files; i++) {
+ struct devcd_file *file = &devcd->files[i];
+
+ sysfs_bin_attr_init(&file->bin_attr);
+ file->bin_attr.attr.name = files[i].name;
+
+ file->bin_attr.attr.mode = 0600;
+ file->bin_attr.size = files[i].datalen;
+ file->bin_attr.private = files[i].data;
+ file->bin_attr.read = devcd_data_read;
+ file->bin_attr.write = devcd_data_write;
+
+ file->read = files[i].read;
+ file->free = files[i].free;
+ }
+
+ return devcd;
+}
+
/**
- * dev_coredumpm - create device coredump with read/free methods
+ * dev_coredumpm_bulk - create a number of device coredump files
* @dev: the struct device for the crashed device
* @owner: the module that contains the read/free functions, use %THIS_MODULE
- * @data: data cookie for the @read/@free functions
- * @datalen: length of the data
* @gfp: allocation flags
- * @read: function to read from the given buffer
- * @free: function to free the given buffer
+ * @files: the configuration of device coredump files
+ * @num_files: the number of device coredump files to create
*
- * Creates a new device coredump for the given device. If a previous one hasn't
- * been read yet, the new coredump is discarded. The data lifetime is determined
- * by the device coredump framework and when it is no longer needed the @free
- * function will be called to free the data.
+ * This function allows drivers to create several device coredump files in
+ * one crashed device.
*/
-void dev_coredumpm(struct device *dev, struct module *owner,
- void *data, size_t datalen, gfp_t gfp,
- ssize_t (*read)(char *buffer, loff_t offset, size_t count,
- void *data, size_t datalen),
- void (*free)(void *data))
+void dev_coredumpm_bulk(struct device *dev, struct module *owner, gfp_t gfp,
+ struct dev_coredumpm_bulk_data *files, int num_files)
{
static atomic_t devcd_count = ATOMIC_INIT(0);
struct devcd_entry *devcd;
struct device *existing;
+ int i;

if (devcd_disabled)
goto free;
@@ -272,15 +293,11 @@ void dev_coredumpm(struct device *dev, struct module *owner,
if (!try_module_get(owner))
goto free;

- devcd = kzalloc(sizeof(*devcd), gfp);
+ devcd = devcd_alloc(files, num_files, gfp);
if (!devcd)
goto put_module;

devcd->owner = owner;
- devcd->data = data;
- devcd->datalen = datalen;
- devcd->read = read;
- devcd->free = free;
devcd->failing_dev = get_device(dev);

device_initialize(&devcd->devcd_dev);
@@ -292,6 +309,12 @@ void dev_coredumpm(struct device *dev, struct module *owner,
if (device_add(&devcd->devcd_dev))
goto put_device;

+ for (i = 0; i < devcd->num_files; i++) {
+ if (device_create_bin_file(&devcd->devcd_dev,
+ &devcd->files[i].bin_attr))
+ /* nothing - some files will be missing */;
+ }
+
if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
"failing_device"))
/* nothing - symlink will be missing */;
@@ -309,7 +332,41 @@ void dev_coredumpm(struct device *dev, struct module *owner,
put_module:
module_put(owner);
free:
- free(data);
+ for (i = 0; i < num_files; i++)
+ files[i].free(files[i].data);
+}
+EXPORT_SYMBOL_GPL(dev_coredumpm_bulk);
+
+/**
+ * dev_coredumpm - create device coredump with read/free methods
+ * @dev: the struct device for the crashed device
+ * @owner: the module that contains the read/free functions, use %THIS_MODULE
+ * @data: data cookie for the @read/@free functions
+ * @datalen: length of the data
+ * @gfp: allocation flags
+ * @read: function to read from the given buffer
+ * @free: function to free the given buffer
+ *
+ * Creates a new device coredump for the given device. If a previous one hasn't
+ * been read yet, the new coredump is discarded. The data lifetime is determined
+ * by the device coredump framework and when it is no longer needed the @free
+ * function will be called to free the data.
+ */
+void dev_coredumpm(struct device *dev, struct module *owner,
+ void *data, size_t datalen, gfp_t gfp,
+ ssize_t (*read)(char *buffer, loff_t offset, size_t count,
+ void *data, size_t datalen),
+ void (*free)(void *data))
+{
+ struct dev_coredumpm_bulk_data bulk_data = {
+ .name = "data",
+ .data = data,
+ .datalen = datalen,
+ .read = read,
+ .free = free,
+ };
+
+ dev_coredumpm_bulk(dev, owner, gfp, &bulk_data, 1);
}
EXPORT_SYMBOL_GPL(dev_coredumpm);

diff --git a/include/linux/devcoredump.h b/include/linux/devcoredump.h
index 269521f..9addb6f 100644
--- a/include/linux/devcoredump.h
+++ b/include/linux/devcoredump.h
@@ -65,6 +65,26 @@ static inline void _devcd_free_sgtable(struct scatterlist *table)
kfree(delete_iter);
}

+/**
+ * struct dev_coredumpm_bulk_data - Data used for dev_coredumpm_bulk
+ *
+ * @name: coredump file name
+ * @data: data cookie for the @read/@free functions
+ * @datalen: length of the data
+ * @read: function to read from the given buffer
+ * @free: function to free the given buffer
+ *
+ * An array of this structure is passed as argument to dev_coredumpm_bulk, and
+ * used to describe each device coredump.
+ */
+struct dev_coredumpm_bulk_data {
+ char *name;
+ void *data;
+ size_t datalen;
+ ssize_t (*read)(char *buffer, loff_t offset, size_t count,
+ void *data, size_t datalen);
+ void (*free)(void *data);
+};

#ifdef CONFIG_DEV_COREDUMP
void dev_coredumpv(struct device *dev, void *data, size_t datalen,
@@ -76,6 +96,9 @@ void dev_coredumpm(struct device *dev, struct module *owner,
void *data, size_t datalen),
void (*free)(void *data));

+void dev_coredumpm_bulk(struct device *dev, struct module *owner, gfp_t gfp,
+ struct dev_coredumpm_bulk_data *files, int num_files);
+
void dev_coredumpsg(struct device *dev, struct scatterlist *table,
size_t datalen, gfp_t gfp);
#else
@@ -95,6 +118,16 @@ dev_coredumpm(struct device *dev, struct module *owner,
free(data);
}

+static inline
+void dev_coredumpm_bulk(struct device *dev, struct module *owner, gfp_t gfp,
+ struct dev_coredumpm_bulk_data *files, int num_files)
+{
+ int i;
+
+ for (i = 0; i < num_files; i++)
+ files[i].free(files[i].data);
+}
+
static inline void dev_coredumpsg(struct device *dev, struct scatterlist *table,
size_t datalen, gfp_t gfp)
{
--
2.7.4

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Previous message: Akinobu Mita: "[PATCH v3 1/7] devcoredump: use memory_read_from_buffer"
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