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pstore: Make spinlock per zone instead of global 

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@google.com>
[kees: updated commit message]
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Joel Fernandes 2016-10-20 00:34:00 -07:00 committed by Kees Cook
parent 959217c84c
commit 109704492e
2 changed files with 6 additions and 6 deletions
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11
fs/pstore/ram_core.c
View File

@ -48,8 +48,6 @@ static inline size_t buffer_start(struct persistent_ram_zone *prz)
return atomic_read(&prz->buffer->start);
}
static DEFINE_RAW_SPINLOCK(buffer_lock);
/* increase and wrap the start pointer, returning the old value */
static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
{
@ -57,7 +55,7 @@ static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
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;
@ -65,7 +63,7 @@ static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
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;
}
@ -77,7 +75,7 @@ static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
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)
@ -89,7 +87,7 @@ static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
atomic_set(&prz->buffer->size, new);
exit:
raw_spin_unlock_irqrestore(&buffer_lock, flags);
raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
}
static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
@ -493,6 +491,7 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
prz->buffer->sig = sig;
persistent_ram_zap(prz);
prz->buffer_lock = __RAW_SPIN_LOCK_UNLOCKED(buffer_lock);
return 0;
}

1
include/linux/pstore_ram.h
View File

@ -40,6 +40,7 @@ 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;