[v8,1/3] devres: provide devm_krealloc()

Message ID	20200820185110.17828-2-brgl@bgdev.pl (mailing list archive)
State	New, archived
Headers	show Return-Path: <SRS0=LZIF=B6=vger.kernel.org=linux-iio-owner@kernel.org> From: Bartosz Golaszewski <brgl@bgdev.pl> To: Jonathan Cameron <jic23@kernel.org>, Hartmut Knaack <knaack.h@gmx.de>, Lars-Peter Clausen <lars@metafoo.de>, Peter Meerwald-Stadler <pmeerw@pmeerw.net>, Michal Simek <michal.simek@xilinx.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Guenter Roeck <linux@roeck-us.net>, Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: linux-iio@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski <bgolaszewski@baylibre.com> Subject: [PATCH v8 1/3] devres: provide devm_krealloc() Date: Thu, 20 Aug 2020 20:51:08 +0200 Message-Id: <20200820185110.17828-2-brgl@bgdev.pl> In-Reply-To: <20200820185110.17828-1-brgl@bgdev.pl> References: <20200820185110.17828-1-brgl@bgdev.pl> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-iio-owner@vger.kernel.org Precedence: bulk
Series	devres: provide and use devm_krealloc() \| expand [v8,0/3] devres: provide and use devm_krealloc() [v8,1/3] devres: provide devm_krealloc() [v8,2/3] hwmon: pmbus: use more devres helpers [v8,3/3] iio: adc: xilinx-xadc: use devm_krealloc()

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..55f3abb966ee 100644 --- a/drivers/base/devres.c +++ b/drivers/base/devres.c @@ -36,6 +36,16 @@ struct devres { u8 __aligned(ARCH_KMALLOC_MINALIGN) data[]; }; +static struct devres *to_devres(void *data) +{ + return 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 +136,14 @@ 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 +855,102 @@ 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 (total_old_size == 0) { + WARN(1, "Pointer doesn't point to dynamically allocated memory."); + return NULL; + } + + /* + * 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; + + /* + * Otherwise: allocate new, larger chunk. We need to allocate before + * taking the lock as most probably the caller uses GFP_KERNEL. + */ + new_dr = alloc_dr(devm_kmalloc_release, + total_new_size, gfp, dev_to_node(dev)); + if (!new_dr) + return NULL; + + /* + * The spinlock protects the linked list against concurrent + * modifications but not the resource itself. + */ + 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); + + /* + * We can copy the memory contents after releasing the lock as we're + * no longer modyfing the list links. + */ + memcpy(new_dr->data, old_dr->data, devres_data_size(total_old_size)); + /* + * Same for releasing the old devres - it's now been removed from the + * list. This is also the reason why we must not use devm_kfree() - the + * links are no longer valid. + */ + 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,

[v8,1/3] devres: provide devm_krealloc()

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