[PATCH] efi: Avoid sysfs spew on reboot and panic

[Matthew Garrett]

Right now all pstore accesses to efivars will delete or create new sysfs
nodes. This is less than ideal if we've paniced or are rebooting, since
we're in entirely the wrong context to do this kind of thing. Add the
reason to the pstore callback and make sure we only manipulate the files
if we're still going to be alive afterwards.

Signed-off-by: Matthew Garrett <mjg@xxxxxxxxxx>
Reported-by: Seiji Aguchi <saguchi@xxxxxxxxxx>
---
 drivers/acpi/apei/erst.c   |    6 ++++--
 drivers/firmware/efivars.c |   17 +++++++++++++----
 fs/pstore/platform.c       |    7 ++++---
 include/linux/kmsg_dump.h  |    1 +
 include/linux/pstore.h     |    5 ++++-
 5 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/drivers/acpi/apei/erst.c b/drivers/acpi/apei/erst.c
index 2ca59dc..a6b5dc1 100644
--- a/drivers/acpi/apei/erst.c
+++ b/drivers/acpi/apei/erst.c
@@ -934,7 +934,8 @@ static int erst_close_pstore(struct pstore_info *psi);
 static ssize_t erst_reader(u64 *id, enum pstore_type_id *type,
 			   struct timespec *time, struct pstore_info *psi);
 static u64 erst_writer(enum pstore_type_id type, unsigned int part,
-		       size_t size, struct pstore_info *psi);
+		       enum kmsg_dump_reason reason, size_t size,
+		       struct pstore_info *psi);
 static int erst_clearer(enum pstore_type_id type, u64 id,
 			struct pstore_info *psi);
 
@@ -1041,7 +1042,8 @@ out:
 }
 
 static u64 erst_writer(enum pstore_type_id type, unsigned int part,
-		       size_t size, struct pstore_info *psi)
+		       enum kmsg_dump_reason reason, size_t size,
+		       struct pstore_info *psi)
 {
 	struct cper_pstore_record *rcd = (struct cper_pstore_record *)
 					(erst_info.buf - sizeof(*rcd));
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index eb80b54..0510319 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -491,7 +491,8 @@ static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
 }
 
 static u64 efi_pstore_write(enum pstore_type_id type, unsigned int part,
-			    size_t size, struct pstore_info *psi)
+			    enum kmsg_dump_reason reason, size_t size,
+			    struct pstore_info *psi)
 {
 	char name[DUMP_NAME_LEN];
 	char stub_name[DUMP_NAME_LEN];
@@ -544,6 +545,14 @@ static u64 efi_pstore_write(enum pstore_type_id type, unsigned int part,
 
 	spin_unlock(&efivars->lock);
 
+	/*
+	 * If it's more severe than KMSG_DUMP_OOPS then we're already dead.
+	 * Don't bother playing with sysfs.
+	 */
+
+	if (reason > KMSG_DUMP_OOPS)
+		return part;
+
 	if (found)
 		efivar_unregister(found);
 
@@ -552,14 +561,13 @@ static u64 efi_pstore_write(enum pstore_type_id type, unsigned int part,
 					  utf16_strsize(efi_name,
 							DUMP_NAME_LEN * 2),
 					  efi_name, &vendor);
-
 	return part;
 };
 
 static int efi_pstore_erase(enum pstore_type_id type, u64 id,
 			    struct pstore_info *psi)
 {
-	efi_pstore_write(type, id, 0, psi);
+	efi_pstore_write(type, id, KMSG_DUMP_UNKNOWN, 0, psi);
 
 	return 0;
 }
@@ -581,7 +589,8 @@ static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
 }
 
 static u64 efi_pstore_write(enum pstore_type_id type, unsigned int part,
-			    size_t size, struct pstore_info *psi)
+			    enum kmsg_dump_reason reason, size_t size,
+			    struct pstore_info *psi)
 {
 	return 0;
 }
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index c5300ec..02117cc 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -51,7 +51,8 @@ void pstore_set_kmsg_bytes(int bytes)
 static int	oopscount;
 
 static char *reason_str[] = {
-	"Oops", "Panic", "Kexec", "Restart", "Halt", "Poweroff", "Emergency"
+	"Unknown", "Oops", "Panic", "Kexec", "Restart", "Halt", "Poweroff",
+	"Emergency"
 };
 
 /*
@@ -97,7 +98,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
 		memcpy(dst, s1 + s1_start, l1_cpy);
 		memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
 
-		id = psinfo->write(PSTORE_TYPE_DMESG, part,
+		id = psinfo->write(PSTORE_TYPE_DMESG, part, reason,
 				   hsize + l1_cpy + l2_cpy, psinfo);
 		if (reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 			pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id,
@@ -207,7 +208,7 @@ int pstore_write(enum pstore_type_id type, char *buf, size_t size)
 
 	mutex_lock(&psinfo->buf_mutex);
 	memcpy(psinfo->buf, buf, size);
-	id = psinfo->write(type, 0, size, psinfo);
+	id = psinfo->write(type, 0, KMSG_DUMP_UNKNOWN, size, psinfo);
 	if (pstore_is_mounted())
 		pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id, psinfo->buf,
 			      size, CURRENT_TIME, psinfo);
diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
index ee0c952..b5ffe79 100644
--- a/include/linux/kmsg_dump.h
+++ b/include/linux/kmsg_dump.h
@@ -16,6 +16,7 @@
 #include <linux/list.h>
 
 enum kmsg_dump_reason {
+	KMSG_DUMP_UNKNOWN,
 	KMSG_DUMP_OOPS,
 	KMSG_DUMP_PANIC,
 	KMSG_DUMP_KEXEC,
diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index cc03bbf..fa049e8 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -22,6 +22,8 @@
 #ifndef _LINUX_PSTORE_H
 #define _LINUX_PSTORE_H
 
+#include <linux/kmsg_dump.h>
+
 /* types */
 enum pstore_type_id {
 	PSTORE_TYPE_DMESG	= 0,
@@ -40,7 +42,8 @@ struct pstore_info {
 	ssize_t		(*read)(u64 *id, enum pstore_type_id *type,
 			struct timespec *time, struct pstore_info *psi);
 	u64		(*write)(enum pstore_type_id type, unsigned int part,
-			size_t size, struct pstore_info *psi);
+			enum kmsg_dump_reason reason, size_t size,
+			struct pstore_info *psi);
 	int		(*erase)(enum pstore_type_id type, u64 id,
 			struct pstore_info *psi);
 	void		*data;
-- 
1.7.6.2

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