[PATCH v5 04/12] pstore/blk: Provide way to choose pstore frontend support

From: WeiXiong Liao
Date: Sat May 09 2020 - 07:15:39 EST


Most pstore backends lack support for all the pstore frontends, only
handling kmsg dump and not things like pmsg, console, and ftrace.
Provide a way for drivers using pstore/blk to list which frontends they
expect to support.

Signed-off-by: WeiXiong Liao <liaoweixiong@xxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/1585126506-18635-4-git-send-email-liaoweixiong@xxxxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
fs/pstore/blk.c | 18 ++++++++++++++----
include/linux/pstore_blk.h | 4 +++-
2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/fs/pstore/blk.c b/fs/pstore/blk.c
index e249b22ff55f..57d9d180511e 100644
--- a/fs/pstore/blk.c
+++ b/fs/pstore/blk.c
@@ -67,6 +67,9 @@
*
* @total_size: The total size in bytes pstore/blk can use. It must be greater
* than 4096 and be multiple of 4096.
+ * @flags: Refer to macro starting with PSTORE_FLAGS defined in
+ * linux/pstore.h. It means what front-ends this device support.
+ * Zero means all backends for compatible.
* @read: The general read operation. Both of the function parameters
* @size and @offset are relative value to bock device (not the
* whole disk).
@@ -79,6 +82,7 @@
*/
struct psblk_device {
unsigned long total_size;
+ unsigned int flags;
psz_read_op read;
psz_write_op write;
psz_write_op panic_write;
@@ -104,8 +108,11 @@ static int psblk_register_do(struct psblk_device *dev)
return -ENOMEM;
}

-#define verify_size(name, alignsize) { \
- long _##name_ = (name); \
+ /* zero means all backends for compatible */
+ if (!dev->flags)
+ dev->flags = UINT_MAX;
+#define verify_size(name, alignsize, enable) { \
+ long _##name_ = (enable) ? (name) : 0; \
_##name_ = _##name_ <= 0 ? 0 : (_##name_ * 1024); \
if (_##name_ & ((alignsize) - 1)) { \
pr_info(#name " must align to %d\n", \
@@ -116,7 +123,7 @@ static int psblk_register_do(struct psblk_device *dev)
pstore_zone_info->name = _##name_; \
}

- verify_size(kmsg_size, 4096);
+ verify_size(kmsg_size, 4096, dev->flags & PSTORE_FLAGS_DMESG);
#undef verify_size

pstore_zone_info->total_size = dev->total_size;
@@ -312,6 +319,7 @@ static struct bdev_info *psblk_get_bdev_info(void)
* psblk_register_blkdev() - register block device to pstore/blk
*
* @major: the major device number of registering device
+ * @flags: refer to macro starting with PSTORE_FLAGS defined in linux/pstore.h
* @panic_write: the interface for panic case.
*
* Only the matching major to @blkdev can register.
@@ -322,7 +330,8 @@ static struct bdev_info *psblk_get_bdev_info(void)
* * 0 - OK
* * Others - something error.
*/
-int psblk_register_blkdev(unsigned int major, psblk_panic_write_op panic_write)
+int psblk_register_blkdev(unsigned int major, unsigned int flags,
+ psblk_panic_write_op panic_write)
{
struct block_device *bdev;
struct psblk_device dev = {0};
@@ -353,6 +362,7 @@ int psblk_register_blkdev(unsigned int major, psblk_panic_write_op panic_write)
blkdev_panic_write = panic_write;

dev.total_size = psblk_bdev_size(bdev);
+ dev.flags = flags;
dev.panic_write = panic_write ? psblk_blk_panic_write : NULL;
dev.read = psblk_generic_blk_read;
dev.write = psblk_generic_blk_write;
diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h
index 5ff465e3953e..d8f609e60288 100644
--- a/include/linux/pstore_blk.h
+++ b/include/linux/pstore_blk.h
@@ -4,6 +4,7 @@
#define __PSTORE_BLK_H_

#include <linux/types.h>
+#include <linux/pstore.h>
#include <linux/pstore_zone.h>

/**
@@ -20,7 +21,8 @@
typedef int (*psblk_panic_write_op)(const char *buf, sector_t start_sect,
sector_t sects);

-int psblk_register_blkdev(unsigned int major, psblk_panic_write_op panic_write);
+int psblk_register_blkdev(unsigned int major, unsigned int flags,
+ psblk_panic_write_op panic_write);
void psblk_unregister_blkdev(unsigned int major);
int psblk_blkdev_info(dev_t *devt, sector_t *nr_sects, sector_t *start_sect);

--
1.9.1