From b264ba41b2dbc11d2429baa9d074e346a635efdc Mon Sep 17 00:00:00 2001 From: Bartosz Golaszewski Date: Mon, 24 Aug 2020 19:38:57 +0200 Subject: [PATCH] devres: provide devm_krealloc() add this patch for arm-cmn commit f82485722e5de5ebb08d3a1dd7302203346dbff9 upstream. 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 Reviewed-by: Andy Shevchenko Link: https://lore.kernel.org/r/20200824173859.4910-2-brgl@bgdev.pl Signed-off-by: Greg Kroah-Hartman Signed-off-by: Huang Cun --- .../driver-api/driver-model/devres.rst | 1 + drivers/base/devres.c | 105 ++++++++++++++++++ include/linux/device.h | 2 + 3 files changed, 108 insertions(+) diff --git a/Documentation/driver-api/driver-model/devres.rst b/Documentation/driver-api/driver-model/devres.rst index 959d6f394174..fcdaa4bb451d 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 b7cf88644826..89a1b8963978 100644 --- a/drivers/base/devres.c +++ b/drivers/base/devres.c @@ -126,6 +126,14 @@ 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) @@ -834,6 +842,103 @@ 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(container_of(ptr, struct devres, data)); + 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); + kfree(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, + total_old_size - offsetof(struct devres, data)); + /* + * 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 5629db1453ae..50d7c180ab3b 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -912,6 +912,8 @@ extern int devres_release_group(struct device *dev, void *id); /* managed devm_k.alloc/kfree for device drivers */ extern 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; extern __printf(3, 0) char *devm_kvasprintf(struct device *dev, gfp_t gfp, const char *fmt, va_list ap) __malloc;