3.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Joel Fernandes <joelaf@xxxxxxxxxx>
commit 109704492ef637956265ec2eb72ae7b3b39eb6f4 upstream.
Currently pstore has a global spinlock for all zones. Since the zones
are independent and modify different areas of memory, there's no need
to have a global lock, so we should use a per-zone lock as introduced
here. Also, when ramoops's ftrace use-case has a FTRACE_PER_CPU flag
introduced later, which splits the ftrace memory area into a single zone
per CPU, it will eliminate the need for locking. In preparation for this,
make the locking optional.
Signed-off-by: Joel Fernandes <joelaf@xxxxxxxxxx>
[kees: updated commit message]
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Leo Yan <leo.yan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/pstore/ram_core.c | 11 +++++------
include/linux/pstore_ram.h | 1 +
2 files changed, 6 insertions(+), 6 deletions(-)
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -80,8 +80,6 @@ static void buffer_size_add_atomic(struc
} while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
}
-static DEFINE_RAW_SPINLOCK(buffer_lock);
-
/* increase and wrap the start pointer, returning the old value */
static size_t buffer_start_add_locked(struct persistent_ram_zone *prz, size_t a)
{
@@ -89,7 +87,7 @@ static size_t buffer_start_add_locked(st
int new;
unsigned long flags;
- raw_spin_lock_irqsave(&buffer_lock, flags);
+ raw_spin_lock_irqsave(&prz->buffer_lock, flags);
old = atomic_read(&prz->buffer->start);
new = old + a;
@@ -97,7 +95,7 @@ static size_t buffer_start_add_locked(st
new -= prz->buffer_size;
atomic_set(&prz->buffer->start, new);
- raw_spin_unlock_irqrestore(&buffer_lock, flags);
+ raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
return old;
}
@@ -109,7 +107,7 @@ static void buffer_size_add_locked(struc
size_t new;
unsigned long flags;
- raw_spin_lock_irqsave(&buffer_lock, flags);
+ raw_spin_lock_irqsave(&prz->buffer_lock, flags);
old = atomic_read(&prz->buffer->size);
if (old == prz->buffer_size)
@@ -121,7 +119,7 @@ static void buffer_size_add_locked(struc
atomic_set(&prz->buffer->size, new);
exit:
- raw_spin_unlock_irqrestore(&buffer_lock, flags);
+ raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
}
static size_t (*buffer_start_add)(struct persistent_ram_zone *, size_t) = buffer_start_add_atomic;
@@ -489,6 +487,7 @@ static int persistent_ram_post_init(stru
prz->buffer->sig = sig;
persistent_ram_zap(prz);
+ prz->buffer_lock = __RAW_SPIN_LOCK_UNLOCKED(buffer_lock);
return 0;
}
--- a/include/linux/pstore_ram.h
+++ b/include/linux/pstore_ram.h
@@ -39,6 +39,7 @@ struct persistent_ram_zone {
void *vaddr;
struct persistent_ram_buffer *buffer;
size_t buffer_size;
+ raw_spinlock_t buffer_lock;
/* ECC correction */
char *par_buffer;