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Subject[PATCH] pstore: Move kmsg_bytes default into Kconfig
Date
From: Vasile-Laurentiu Stanimir <vasile-laurentiu.stanimir@windriver.com>

While kmsg_bytes can be set for pstore via mount, if a crash occurs
before the mount only partial console log will be stored as kmsg_bytes
defaults to a potentially different hardcoded value in the kernel
(PSTORE_DEFAULT_KMSG_BYTES). This makes it impossible to analyze valuable
post-mortem data especially on the embedded development or in the process
of bringing up new boards. Change this value to be a Kconfig option
with the default of old PSTORE_DEFAULT_KMSG_BYTES

Signed-off-by: Vasile-Laurentiu Stanimir <vasile-laurentiu.stanimir@windriver.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
This was sent off-list, so I'm resending it to lkml (with the commit log
cleaned up sligthly) before I push it into for-next/pstore.
---
fs/pstore/Kconfig | 8 ++++++++
fs/pstore/inode.c | 2 +-
fs/pstore/internal.h | 1 -
fs/pstore/platform.c | 2 +-
4 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index e16a49ebfe54..8adabde685f1 100644
--- a/fs/pstore/Kconfig
+++ b/fs/pstore/Kconfig
@@ -14,6 +14,14 @@ config PSTORE
If you don't have a platform persistent store driver,
say N.

+config PSTORE_DEFAULT_KMSG_BYTES
+ int "Default kernel log storage space" if EXPERT
+ depends on PSTORE
+ default "10240"
+ help
+ Defines default size of pstore kernel log storage.
+ Can be enlarged if needed, not recommended to shrink it.
+
config PSTORE_DEFLATE_COMPRESS
tristate "DEFLATE (ZLIB) compression"
default y
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index c331efe8de95..93a217e4f563 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -266,7 +266,7 @@ static void parse_options(char *options)
*/
static int pstore_show_options(struct seq_file *m, struct dentry *root)
{
- if (kmsg_bytes != PSTORE_DEFAULT_KMSG_BYTES)
+ if (kmsg_bytes != CONFIG_PSTORE_DEFAULT_KMSG_BYTES)
seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
return 0;
}
diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
index 7fb219042f13..801d6c0b170c 100644
--- a/fs/pstore/internal.h
+++ b/fs/pstore/internal.h
@@ -6,7 +6,6 @@
#include <linux/time.h>
#include <linux/pstore.h>

-#define PSTORE_DEFAULT_KMSG_BYTES 10240
extern unsigned long kmsg_bytes;

#ifdef CONFIG_PSTORE_FTRACE
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 36714df37d5d..32f64abc277c 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -101,7 +101,7 @@ static char *big_oops_buf;
static size_t big_oops_buf_sz;

/* How much of the console log to snapshot */
-unsigned long kmsg_bytes = PSTORE_DEFAULT_KMSG_BYTES;
+unsigned long kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;

void pstore_set_kmsg_bytes(int bytes)
{
--
2.25.1
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