From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933441AbbA1Faj (ORCPT ); Wed, 28 Jan 2015 00:30:39 -0500 Received: from szxga03-in.huawei.com ([119.145.14.66]:50928 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760645AbbA1F34 (ORCPT ); Wed, 28 Jan 2015 00:29:56 -0500 From: HuKeping To: CC: , , , , , , , , , Subject: [PATCH v2 1/2] pstore/ram: avoid atomic accesses for ioremapped regions Date: Wed, 28 Jan 2015 13:23:40 +0800 Message-ID: <1422422621-5003-2-git-send-email-hukeping@huawei.com> X-Mailer: git-send-email 1.8.5.5 In-Reply-To: <1422422621-5003-1-git-send-email-hukeping@huawei.com> References: <1422422621-5003-1-git-send-email-hukeping@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.197.247] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020202.54C873CB.014F,ss=1,re=0.001,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: f629556874642c7be1cac581194c4b6c Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rob Herring For persistent RAM outside of main memory, the memory may have limitations on supported accesses. For internal RAM on highbank platform exclusive accesses are not supported and will hang the system. So atomic_cmpxchg cannot be used. This commit uses spinlock protection for buffer size and start updates on ioremapped regions instead. Signed-off-by: Rob Herring Acked-by: Anton Vorontsov Signed-off-by: Tony Luck [hkp: Backported to 3.10: adjust context] Signed-off-by: HuKeping --- fs/pstore/ram_core.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 52 insertions(+), 2 deletions(-) diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c index 6ff9755..bda61a7 100644 --- a/fs/pstore/ram_core.c +++ b/fs/pstore/ram_core.c @@ -46,7 +46,7 @@ static inline size_t buffer_start(struct persistent_ram_zone *prz) } /* increase and wrap the start pointer, returning the old value */ -static inline size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a) +static size_t buffer_start_add_atomic(struct persistent_ram_zone *prz, size_t a) { int old; int new; @@ -62,7 +62,7 @@ static inline size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a) } /* increase the size counter until it hits the max size */ -static inline void buffer_size_add(struct persistent_ram_zone *prz, size_t a) +static void buffer_size_add_atomic(struct persistent_ram_zone *prz, size_t a) { size_t old; size_t new; @@ -78,6 +78,53 @@ static inline void buffer_size_add(struct persistent_ram_zone *prz, size_t a) } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old); } +static DEFINE_RAW_SPINLOCK(buffer_lock); + +/* increase and wrap the start pointer, returning the old value */ +static size_t buffer_start_add_locked(struct persistent_ram_zone *prz, size_t a) +{ + int old; + int new; + unsigned long flags; + + raw_spin_lock_irqsave(&buffer_lock, flags); + + old = atomic_read(&prz->buffer->start); + new = old + a; + while (unlikely(new > prz->buffer_size)) + new -= prz->buffer_size; + atomic_set(&prz->buffer->start, new); + + raw_spin_unlock_irqrestore(&buffer_lock, flags); + + return old; +} + +/* increase the size counter until it hits the max size */ +static void buffer_size_add_locked(struct persistent_ram_zone *prz, size_t a) +{ + size_t old; + size_t new; + unsigned long flags; + + raw_spin_lock_irqsave(&buffer_lock, flags); + + old = atomic_read(&prz->buffer->size); + if (old == prz->buffer_size) + goto exit; + + new = old + a; + if (new > prz->buffer_size) + new = prz->buffer_size; + atomic_set(&prz->buffer->size, new); + +exit: + raw_spin_unlock_irqrestore(&buffer_lock, flags); +} + +static size_t (*buffer_start_add)(struct persistent_ram_zone *, size_t) = buffer_start_add_atomic; +static void (*buffer_size_add)(struct persistent_ram_zone *, size_t) = buffer_size_add_atomic; + static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz, uint8_t *data, size_t len, uint8_t *ecc) { @@ -379,6 +426,9 @@ static void *persistent_ram_iomap(phys_addr_t start, size_t size, return NULL; } + buffer_start_add = buffer_start_add_locked; + buffer_size_add = buffer_size_add_locked; + if (memtype) va = ioremap(start, size); else -- 1.8.5.5