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Commit 10970449 authored by Joel Fernandes's avatar Joel Fernandes Committed by Kees Cook
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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: default avatarJoel Fernandes <joelaf@google.com>
[kees: updated commit message]
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent 959217c8

fs/pstore/ram_core.c

+5 −6
Original line number Diff line number Diff line
@@ -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;

}

include/linux/pstore_ram.h

+1 −0
Original line number Diff line number Diff line
@@ -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;