Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965652AbcKKWWf (ORCPT ); Fri, 11 Nov 2016 17:22:35 -0500 Received: from mail-pf0-f177.google.com ([209.85.192.177]:33226 "EHLO mail-pf0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965602AbcKKWWc (ORCPT ); Fri, 11 Nov 2016 17:22:32 -0500 From: Kees Cook To: Joel Fernandes Cc: Kees Cook , Anton Vorontsov , Colin Cross , Tony Luck , linux-kernel@vger.kernel.org Subject: [PATCH v3 3/8] pstore: Allow prz to control need for locking Date: Fri, 11 Nov 2016 14:21:48 -0800 Message-Id: <1478902913-143778-4-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1478902913-143778-1-git-send-email-keescook@chromium.org> References: <1478902913-143778-1-git-send-email-keescook@chromium.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5307 Lines: 155 From: Joel Fernandes In preparation of not locking at all for certain buffers depending on if there's contention, make locking optional depending on the initialization of the prz. Signed-off-by: Joel Fernandes [kees: moved locking flag into prz instead of via caller arguments] Signed-off-by: Kees Cook --- fs/pstore/ram.c | 5 +++-- fs/pstore/ram_core.c | 20 +++++++++++++------- include/linux/pstore_ram.h | 10 +++++++++- 3 files changed, 25 insertions(+), 10 deletions(-) diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c index 6d1393965b0a..86ac59066fba 100644 --- a/fs/pstore/ram.c +++ b/fs/pstore/ram.c @@ -432,7 +432,7 @@ static int ramoops_init_przs(struct device *dev, struct ramoops_context *cxt, for (i = 0; i < cxt->max_dump_cnt; i++) { cxt->przs[i] = persistent_ram_new(*paddr, cxt->record_size, 0, &cxt->ecc_info, - cxt->memtype); + cxt->memtype, 0); if (IS_ERR(cxt->przs[i])) { err = PTR_ERR(cxt->przs[i]); dev_err(dev, "failed to request mem region (0x%zx@0x%llx): %d\n", @@ -469,7 +469,8 @@ static int ramoops_init_prz(struct device *dev, struct ramoops_context *cxt, return -ENOMEM; } - *prz = persistent_ram_new(*paddr, sz, sig, &cxt->ecc_info, cxt->memtype); + *prz = persistent_ram_new(*paddr, sz, sig, &cxt->ecc_info, + cxt->memtype, 0); if (IS_ERR(*prz)) { int err = PTR_ERR(*prz); diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c index cb92055e6016..0cc23cb18719 100644 --- a/fs/pstore/ram_core.c +++ b/fs/pstore/ram_core.c @@ -55,7 +55,8 @@ static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a) int new; unsigned long flags; - raw_spin_lock_irqsave(&prz->buffer_lock, flags); + if (!(prz->flags & PRZ_FLAG_NO_LOCK)) + raw_spin_lock_irqsave(&prz->buffer_lock, flags); old = atomic_read(&prz->buffer->start); new = old + a; @@ -63,7 +64,8 @@ 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(&prz->buffer_lock, flags); + if (!(prz->flags & PRZ_FLAG_NO_LOCK)) + raw_spin_unlock_irqrestore(&prz->buffer_lock, flags); return old; } @@ -75,7 +77,8 @@ static void buffer_size_add(struct persistent_ram_zone *prz, size_t a) size_t new; unsigned long flags; - raw_spin_lock_irqsave(&prz->buffer_lock, flags); + if (!(prz->flags & PRZ_FLAG_NO_LOCK)) + raw_spin_lock_irqsave(&prz->buffer_lock, flags); old = atomic_read(&prz->buffer->size); if (old == prz->buffer_size) @@ -87,7 +90,8 @@ static void buffer_size_add(struct persistent_ram_zone *prz, size_t a) atomic_set(&prz->buffer->size, new); exit: - raw_spin_unlock_irqrestore(&prz->buffer_lock, flags); + if (!(prz->flags & PRZ_FLAG_NO_LOCK)) + raw_spin_unlock_irqrestore(&prz->buffer_lock, flags); } static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz, @@ -463,7 +467,8 @@ static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size, } static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig, - struct persistent_ram_ecc_info *ecc_info) + struct persistent_ram_ecc_info *ecc_info, + unsigned long flags) { int ret; @@ -492,6 +497,7 @@ 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); + prz->flags = flags; return 0; } @@ -516,7 +522,7 @@ void persistent_ram_free(struct persistent_ram_zone *prz) struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size, u32 sig, struct persistent_ram_ecc_info *ecc_info, - unsigned int memtype) + unsigned int memtype, u32 flags) { struct persistent_ram_zone *prz; int ret = -ENOMEM; @@ -531,7 +537,7 @@ struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size, if (ret) goto err; - ret = persistent_ram_post_init(prz, sig, ecc_info); + ret = persistent_ram_post_init(prz, sig, ecc_info, flags); if (ret) goto err; diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h index 244d2423dbaf..4058bf991868 100644 --- a/include/linux/pstore_ram.h +++ b/include/linux/pstore_ram.h @@ -24,6 +24,13 @@ #include #include +/* + * Choose whether access to the RAM zone requires locking or not. If a zone + * can be written to from different CPUs like with ftrace for example, then + * PRZ_FLAG_NO_LOCK is used. For all other cases, locking is required. + */ +#define PRZ_FLAG_NO_LOCK BIT(0) + struct persistent_ram_buffer; struct rs_control; @@ -40,6 +47,7 @@ struct persistent_ram_zone { void *vaddr; struct persistent_ram_buffer *buffer; size_t buffer_size; + u32 flags; raw_spinlock_t buffer_lock; /* ECC correction */ @@ -56,7 +64,7 @@ struct persistent_ram_zone { struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size, u32 sig, struct persistent_ram_ecc_info *ecc_info, - unsigned int memtype); + unsigned int memtype, u32 flags); void persistent_ram_free(struct persistent_ram_zone *prz); void persistent_ram_zap(struct persistent_ram_zone *prz); -- 2.7.4