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[2.15.159.20]) by smtp.gmail.com with ESMTPSA id k184sm29747177wme.1.2020.08.17.10.05.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Aug 2020 10:05:40 -0700 (PDT) From: Bartosz Golaszewski To: Jonathan Cameron , Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald-Stadler , Michal Simek , Greg Kroah-Hartman , Guenter Roeck , Andy Shevchenko Cc: linux-iio@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski Subject: [PATCH v7 1/3] devres: provide devm_krealloc() Date: Mon, 17 Aug 2020 19:05:33 +0200 Message-Id: <20200817170535.17041-2-brgl@bgdev.pl> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20200817170535.17041-1-brgl@bgdev.pl> References: <20200817170535.17041-1-brgl@bgdev.pl> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Bartosz Golaszewski Implement the managed variant of krealloc(). This function works with all memory allocated by devm_kmalloc() (or devres functions using it implicitly like devm_kmemdup(), devm_kstrdup() etc.). Managed realloc'ed chunks can be manually released with devm_kfree(). Signed-off-by: Bartosz Golaszewski --- .../driver-api/driver-model/devres.rst | 1 + drivers/base/devres.c | 93 +++++++++++++++++++ include/linux/device.h | 2 + 3 files changed, 96 insertions(+) diff --git a/Documentation/driver-api/driver-model/devres.rst b/Documentation/driver-api/driver-model/devres.rst index eaaaafc21134..f318a5c0033c 100644 --- a/Documentation/driver-api/driver-model/devres.rst +++ b/Documentation/driver-api/driver-model/devres.rst @@ -354,6 +354,7 @@ MEM devm_kmalloc() devm_kmalloc_array() devm_kmemdup() + devm_krealloc() devm_kstrdup() devm_kvasprintf() devm_kzalloc() diff --git a/drivers/base/devres.c b/drivers/base/devres.c index ed615d3b9cf1..bfe46e83147e 100644 --- a/drivers/base/devres.c +++ b/drivers/base/devres.c @@ -36,6 +36,17 @@ struct devres { u8 __aligned(ARCH_KMALLOC_MINALIGN) data[]; }; +static struct devres *to_devres(void *data) +{ + return (struct devres *)((u8 *)data - ALIGN(sizeof(struct devres), + ARCH_KMALLOC_MINALIGN)); +} + +static size_t devres_data_size(size_t total_size) +{ + return total_size - ALIGN(sizeof(struct devres), ARCH_KMALLOC_MINALIGN); +} + struct devres_group { struct devres_node node[2]; void *id; @@ -126,6 +137,14 @@ static void add_dr(struct device *dev, struct devres_node *node) list_add_tail(&node->entry, &dev->devres_head); } +static void replace_dr(struct device *dev, + struct devres_node *old, struct devres_node *new) +{ + devres_log(dev, old, "REPLACE"); + BUG_ON(!list_empty(&new->entry)); + list_replace(&old->entry, &new->entry); +} + #ifdef CONFIG_DEBUG_DEVRES void * __devres_alloc_node(dr_release_t release, size_t size, gfp_t gfp, int nid, const char *name) @@ -837,6 +856,80 @@ void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp) } EXPORT_SYMBOL_GPL(devm_kmalloc); +/** + * devm_krealloc - Resource-managed krealloc() + * @dev: Device to re-allocate memory for + * @ptr: Pointer to the memory chunk to re-allocate + * @new_size: New allocation size + * @gfp: Allocation gfp flags + * + * Managed krealloc(). Resizes the memory chunk allocated with devm_kmalloc(). + * Behaves similarly to regular krealloc(): if @ptr is NULL or ZERO_SIZE_PTR, + * it's the equivalent of devm_kmalloc(). If new_size is zero, it frees the + * previously allocated memory and returns ZERO_SIZE_PTR. This function doesn't + * change the order in which the release callback for the re-alloc'ed devres + * will be called (except when falling back to devm_kmalloc() or when freeing + * resources when new_size is zero). The contents of the memory are preserved + * up to the lesser of new and old sizes. + */ +void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp) +{ + size_t total_new_size, total_old_size; + struct devres *old_dr, *new_dr; + unsigned long flags; + + if (unlikely(!new_size)) { + devm_kfree(dev, ptr); + return ZERO_SIZE_PTR; + } + + if (unlikely(ZERO_OR_NULL_PTR(ptr))) + return devm_kmalloc(dev, new_size, gfp); + + if (WARN_ON(is_kernel_rodata((unsigned long)ptr))) + /* + * We cannot reliably realloc a const string returned by + * devm_kstrdup_const(). + */ + return NULL; + + if (!check_dr_size(new_size, &total_new_size)) + return NULL; + + total_old_size = ksize(to_devres(ptr)); + + /* + * If new size is smaller or equal to the actual number of bytes + * allocated previously - just return the same pointer. + */ + if (total_new_size <= total_old_size) + return ptr; + + new_dr = alloc_dr(devm_kmalloc_release, + total_new_size, gfp, dev_to_node(dev)); + if (!new_dr) + return NULL; + + spin_lock_irqsave(&dev->devres_lock, flags); + + old_dr = find_dr(dev, devm_kmalloc_release, devm_kmalloc_match, ptr); + if (!old_dr) { + spin_unlock_irqrestore(&dev->devres_lock, flags); + devres_free(new_dr); + WARN(1, "Memory chunk not managed or managed by a different device."); + return NULL; + } + + replace_dr(dev, &old_dr->node, &new_dr->node); + + spin_unlock_irqrestore(&dev->devres_lock, flags); + + memcpy(new_dr->data, old_dr->data, devres_data_size(total_old_size)); + kfree(old_dr); + return new_dr->data; +} +EXPORT_SYMBOL_GPL(devm_krealloc); + /** * devm_kstrdup - Allocate resource managed space and * copy an existing string into that. diff --git a/include/linux/device.h b/include/linux/device.h index ca18da4768e3..5da7d5f0a7ff 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -206,6 +206,8 @@ int devres_release_group(struct device *dev, void *id); /* managed devm_k.alloc/kfree for device drivers */ void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp) __malloc; +void *devm_krealloc(struct device *dev, void *ptr, size_t size, + gfp_t gfp) __must_check; __printf(3, 0) char *devm_kvasprintf(struct device *dev, gfp_t gfp, const char *fmt, va_list ap) __malloc; __printf(3, 4) char *devm_kasprintf(struct device *dev, gfp_t gfp, -- 2.26.1