pstore: Don't allow high traffic options on fragile devices

Some pstore backing devices use on board flash as persistent
storage. These have limited numbers of write cycles so it
is a poor idea to use them from high frequency operations.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 10 insertions, 2 deletions

diff --git a/drivers/acpi/apei/erst.c b/drivers/acpi/apei/erst.c
index 26311f23c824..cb1d557fc22c 100644
--- a/drivers/acpi/apei/erst.c
+++ b/drivers/acpi/apei/erst.c
@@ -942,6 +942,7 @@ static int erst_clearer(enum pstore_type_id type, u64 id, int count,
 static struct pstore_info erst_info = {
         .owner          = THIS_MODULE,
         .name           = "erst",
+        .flags          = PSTORE_FLAGS_FRAGILE,
         .open           = erst_open_pstore,
         .close          = erst_close_pstore,
         .read           = erst_reader,
diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c
index 743fd426f21b..4b9dc836dcf9 100644
--- a/drivers/firmware/efi/efi-pstore.c
+++ b/drivers/firmware/efi/efi-pstore.c
@@ -356,6 +356,7 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
 static struct pstore_info efi_pstore_info = {
         .owner          = THIS_MODULE,
         .name           = "efi",
+        .flags          = PSTORE_FLAGS_FRAGILE,
         .open           = efi_pstore_open,
         .close          = efi_pstore_close,
         .read           = efi_pstore_read,
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index b8e93a40a5d3..78c3c2097787 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -443,8 +443,11 @@ int pstore_register(struct pstore_info *psi)
                 pstore_get_records(0);
 
         kmsg_dump_register(&pstore_dumper);
-        pstore_register_console();
-        pstore_register_ftrace();
+
+        if ((psi->flags & PSTORE_FLAGS_FRAGILE) == 0) {
+                pstore_register_console();
+                pstore_register_ftrace();
+        }
 
         if (pstore_update_ms >= 0) {
                 pstore_timer.expires = jiffies +
diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index abd437d0a8a7..ece0c6bbfcc5 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -51,6 +51,7 @@ struct pstore_info {
         char            *buf;
         size_t          bufsize;
         struct mutex    read_mutex;     /* serialize open/read/close */
+        int             flags;
         int             (*open)(struct pstore_info *psi);
         int             (*close)(struct pstore_info *psi);
         ssize_t         (*read)(u64 *id, enum pstore_type_id *type,
@@ -70,6 +71,8 @@ struct pstore_info {
         void            *data;
 };
 
+#define PSTORE_FLAGS_FRAGILE    1
+
 #ifdef CONFIG_PSTORE
 extern int pstore_register(struct pstore_info *);
 extern bool pstore_cannot_block_path(enum kmsg_dump_reason reason);