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    Subject[PATCH v2 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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