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Subject[PATCH 1/7] pstore: Make spinlock per zone instead of global
Date
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,
ramoops's ftrace usecase has a FTRACE_PER_CPU flag introduced in this patch
series which splits the ftrace memory area into a single zone per CPU thus
eliminating the need for locking. In preparation for this, make the locking
optional.

Signed-off-by: Joel Fernandes <joelaf@google.com>
---
fs/pstore/ram_core.c | 11 +++++------
include/linux/pstore_ram.h | 1 +
2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index 3975dee..cb92055 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -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;
}
diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h
index c668c86..244d242 100644
--- a/include/linux/pstore_ram.h
+++ b/include/linux/pstore_ram.h
@@ -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;
--
2.7.4
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