Some pstore backend only supports async mode, so it's possible to do
some IO at the same time. In this case we need to manage the single
psinfo->buf not to broken by concurrent IO.
For example PSTORE_TYPE_CONSOLE IO is serialized by psinfo->buf_lock but
later IO can be issued before finishing previous request. In this case
it overwrites psinfo->buf so the previous result might be broken.
This patch adds psinfo->bufpos field to keep track of current position
in order to use psinfo->buf as a ring buffer. However it's just a
simple, best-effort way of doing that, and provides no 100% guarantee.
It's only effective for small concurrent IO like PSTORE_TYPE_CONSOLE
IMHO.
The new PSTORE_FLAGS_ASYNC flag enables management of buffer position.
The pstore_prepare_buf() is called before accessing the psinfo->buf and
the pstore_update_buf() is called after accessing the buf.
The pstore_get_buf() is provided for psinfo->write callback to determine
the current position of available buffer.
Cc: Anton Vorontsov <anton@xxxxxxxxxx>
Cc: Colin Cross <ccross@xxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Cc: linux-efi@xxxxxxxxxxxxxxx
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
drivers/firmware/efi/efi-pstore.c | 2 +-
fs/pstore/platform.c | 48 +++++++++++++++++++++++++++++++--------
include/linux/pstore.h | 4 ++++
3 files changed, 44 insertions(+), 10 deletions(-)
diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c
index 4daa5acd9117..ae0ffe259e07 100644
--- a/drivers/firmware/efi/efi-pstore.c
+++ b/drivers/firmware/efi/efi-pstore.c
@@ -259,7 +259,7 @@ static int efi_pstore_write(enum pstore_type_id type,
efivar_entry_set_safe(efi_name, vendor, PSTORE_EFI_ATTRIBUTES,
!pstore_cannot_block_path(reason),
- size, psi->buf);
+ size, pstore_get_buf(psi));
if (reason == KMSG_DUMP_OOPS)
efivar_run_worker();
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 76dd604a0f2c..26e2808cf554 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -150,6 +150,27 @@ bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
}
EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
+static void *pstore_prepare_buf(struct pstore_info *psi, size_t len)
+{
+ if (psi->bufpos + len > psi->bufsize ||
+ (psi->flags & PSTORE_FLAGS_ASYNC) == 0)
+ psi->bufpos = 0;
+
+ return psi->buf + psi->bufpos;
+}
+
+static void pstore_update_buf(struct pstore_info *psi, size_t len)
+{
+ if (psi->flags & PSTORE_FLAGS_ASYNC)
+ psi->bufpos += len;
+}
+
+void *pstore_get_buf(struct pstore_info *psi)
+{
+ return psi->buf + psi->bufpos;
+}
+EXPORT_SYMBOL_GPL(pstore_get_buf);
+
#ifdef CONFIG_PSTORE_ZLIB_COMPRESS
/* Derived from logfs_compress() */
static int compress_zlib(const void *in, void *out, size_t inlen, size_t outlen)
@@ -455,18 +476,21 @@ static size_t copy_kmsg_to_buffer(int hsize, size_t len)
{
size_t total_len;
size_t diff;
+ void *dst;
total_len = hsize + len;
+ dst = pstore_prepare_buf(psinfo, total_len);
if (total_len > psinfo->bufsize) {
diff = total_len - psinfo->bufsize + hsize;
- memcpy(psinfo->buf, big_oops_buf, hsize);
- memcpy(psinfo->buf + hsize, big_oops_buf + diff,
+ memcpy(dst, big_oops_buf, hsize);
+ memcpy(dst + hsize, big_oops_buf + diff,
psinfo->bufsize - hsize);
total_len = psinfo->bufsize;
} else
- memcpy(psinfo->buf, big_oops_buf, total_len);
+ memcpy(dst, big_oops_buf, total_len);
+ pstore_update_buf(psinfo, total_len);
return total_len;
}
@@ -500,7 +524,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
}
oopscount++;
while (total < kmsg_bytes) {
- char *dst;
+ char *dst, *buf;
unsigned long size;
int hsize;
int zipped_len = -1;
@@ -514,6 +538,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
} else {
dst = psinfo->buf;
size = psinfo->bufsize;
+ psinfo->bufpos = 0;
}
hsize = sprintf(dst, "%s#%d Part%u\n", why, oopscount, part);
@@ -524,8 +549,9 @@ static void pstore_dump(struct kmsg_dumper *dumper,
break;
if (big_oops_buf && is_locked) {
- zipped_len = pstore_compress(dst, psinfo->buf,
- hsize + len, psinfo->bufsize);
+ buf = pstore_prepare_buf(psinfo, hsize + len);
+ zipped_len = pstore_compress(dst, buf, hsize + len,
+ psinfo->bufsize - psinfo->bufpos);
if (zipped_len > 0) {
compressed = true;
@@ -543,6 +569,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
pstore_new_entry = 1;
total += total_len;
+ pstore_update_buf(psinfo, total_len);
part++;
}
if (is_locked)
@@ -573,6 +600,7 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
while (s < e) {
unsigned long flags;
+ void *dst;
u64 id;
if (c > psinfo->bufsize)
@@ -584,8 +612,10 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
} else {
spin_lock_irqsave(&psinfo->buf_lock, flags);
}
- memcpy(psinfo->buf, s, c);
+ dst = pstore_prepare_buf(psinfo, c);
+ memcpy(dst, s, c);
psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, 0, 0, c, psinfo);
+ pstore_update_buf(psinfo, c);
spin_unlock_irqrestore(&psinfo->buf_lock, flags);
s += c;
c = e - s;
@@ -619,8 +649,8 @@ static int pstore_write_compat(enum pstore_type_id type,
bool compressed, size_t size,
struct pstore_info *psi)
{
- return psi->write_buf(type, reason, id, part, psinfo->buf, compressed,
- size, psi);
+ return psi->write_buf(type, reason, id, part, pstore_get_buf(psinfo),
+ compressed, size, psi);
}
/*
diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index 9790904de6d2..14f524177b1f 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -52,6 +52,7 @@ struct pstore_info {
spinlock_t buf_lock; /* serialize access to 'buf' */
char *buf;
size_t bufsize;
+ size_t bufpos;
struct mutex read_mutex; /* serialize open/read/close */
int flags;
int (*open)(struct pstore_info *psi);
@@ -79,8 +80,11 @@ struct pstore_info {
#define PSTORE_FLAGS_FTRACE (1 << 2)
#define PSTORE_FLAGS_PMSG (1 << 3)
+#define PSTORE_FLAGS_ASYNC (1 << 30)
+
extern int pstore_register(struct pstore_info *);
extern void pstore_unregister(struct pstore_info *);
extern bool pstore_cannot_block_path(enum kmsg_dump_reason reason);
+extern void *pstore_get_buf(struct pstore_info *);
#endif /*_LINUX_PSTORE_H*/
--
2.8.0
--
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