From: Kees Cook <keescook@chromium.org>
To: Joel Fernandes <joelaf@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Anton Vorontsov <anton@enomsg.org>,
Colin Cross <ccross@android.com>, Tony Luck <tony.luck@intel.com>
Subject: Re: [PATCH v2 1/7] pstore: Make spinlock per zone instead of global
Date: Thu, 10 Nov 2016 16:06:33 -0800 [thread overview]
Message-ID: <CAGXu5jLU7UpqmHztgmfufTDRj+NUBfzBkAmDF_sgmrbVSQ2xtg@mail.gmail.com> (raw)
In-Reply-To: <1476948846-15006-2-git-send-email-joelaf@google.com>
On Thu, Oct 20, 2016 at 12:34 AM, Joel Fernandes <joelaf@google.com> wrote:
> 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
>
This one looks good, thanks. I'll get this in for -next since it's a
good clean-up on its own.
Have you put these patches through scripts/checkpatch.pl? Some of
lines wrap or have wide commit messages, but that's just cosmetic to
fix up.
-Kees
--
Kees Cook
Nexus Security
next prev parent reply other threads:[~2016-11-11 0:06 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-20 7:33 [PATCH v2 0/7] pstore: Improve performance of ftrace backend with ramoops Joel Fernandes
2016-10-20 7:34 ` [PATCH v2 1/7] pstore: Make spinlock per zone instead of global Joel Fernandes
2016-11-11 0:06 ` Kees Cook [this message]
2016-11-11 0:24 ` Joel Fernandes
2016-10-20 7:34 ` [PATCH v2 2/7] pstore: locking: dont lock unless caller asks to Joel Fernandes
2016-11-11 0:10 ` Kees Cook
2016-11-11 18:16 ` Kees Cook
2016-10-20 7:34 ` [PATCH v2 3/7] pstore: Warn for the case of PSTORE_TYPE_PMSG write using deprecated function Joel Fernandes
2016-11-11 0:10 ` Kees Cook
2016-10-20 7:34 ` [PATCH v2 4/7] pstore: Make ramoops_init_przs generic for other prz arrays Joel Fernandes
2016-11-11 0:12 ` Kees Cook
2016-10-20 7:34 ` [PATCH v2 5/7] ramoops: Split ftrace buffer space into per-CPU zones Joel Fernandes
2016-11-11 0:13 ` Kees Cook
2016-11-11 0:16 ` Joel Fernandes
2016-11-11 18:27 ` Kees Cook
2016-10-20 7:34 ` [PATCH v2 6/7] pstore: Add support to store timestamp counter in ftrace records Joel Fernandes
2016-11-11 0:15 ` Kees Cook
2016-11-11 0:21 ` Joel Fernandes
2016-11-11 18:29 ` Kees Cook
2016-10-20 7:34 ` [PATCH v2 7/7] pstore: Merge per-CPU ftrace zones into one zone for output Joel Fernandes
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