If a dma_mask is provided as part of platform_device_info, platform_device_register_full() allocate memory for a u64 using kmalloc().
A comment in the code state that "[t]his memory isn't freed when the device is put". It's never a good thing to leak memory, but there's only very few users of platform_device_info's dma_mask, and those are mostly "static" devices that are not going to be plugged/unplugged. So memory leak is not really an issue, but allocating 8 bytes through kmalloc() seems overkill, so this patch moves dma_mask after the platform_device struct, dynamically allocated along the name buffer. With dma_mask part of the memory allocated for the platform_device struct, like name buffer, it will be released with it: no memory leak, no small allocation. The drawback is the additional code needed to handle dma_mask allocation: Before (on next-20140113 with gcc-4.8): text data bss dec hex filename 5600 472 32 6104 17d8 obj-arm/drivers/base/platform.o 5927 532 32 6491 195b obj-i386/drivers/base/platform.o 7036 960 48 8044 1f6c obj-x86_64/drivers/base/platform.o After: text data bss dec hex filename 5672 472 32 6176 1820 obj-arm/drivers/base/platform.o 6007 532 32 6571 19ab obj-i386/drivers/base/platform.o 7132 960 48 8140 1fcc obj-x86_64/drivers/base/platform.o Changes from v0 [1]: - small rewrite to squeeze the patch to a bare minimal [1] http://lkml.kernel.org/r/1386886207-2735-1-git-send-email-ydrone...@opteya.com Signed-off-by: Yann Droneaud <ydrone...@opteya.com> --- drivers/base/platform.c | 82 +++++++++++++++++++++++++++++++++++++------------ 1 file changed, 62 insertions(+), 20 deletions(-) diff --git a/drivers/base/platform.c b/drivers/base/platform.c index 3a94b799f166..0741be056885 100644 --- a/drivers/base/platform.c +++ b/drivers/base/platform.c @@ -157,7 +157,7 @@ EXPORT_SYMBOL_GPL(platform_add_devices); struct platform_object { struct platform_device pdev; - char name[1]; + char payload[0]; }; /** @@ -186,6 +186,25 @@ static void platform_device_release(struct device *dev) kfree(pa); } +static struct platform_object *platform_object_alloc(size_t payload) +{ + struct platform_object *pa; + + pa = kzalloc(sizeof(*pa) + payload, GFP_KERNEL); + + return pa; +} + +static void platform_object_init(struct platform_object *pa, + const char *name, int id) +{ + pa->pdev.name = name; + pa->pdev.id = id; + device_initialize(&pa->pdev.dev); + pa->pdev.dev.release = platform_device_release; + arch_setup_pdev_archdata(&pa->pdev); +} + /** * platform_device_alloc - create a platform device * @name: base name of the device we're adding @@ -198,14 +217,10 @@ struct platform_device *platform_device_alloc(const char *name, int id) { struct platform_object *pa; - pa = kzalloc(sizeof(struct platform_object) + strlen(name), GFP_KERNEL); + pa = platform_object_alloc(strlen(name) + 1); if (pa) { - strcpy(pa->name, name); - pa->pdev.name = pa->name; - pa->pdev.id = id; - device_initialize(&pa->pdev.dev); - pa->pdev.dev.release = platform_device_release; - arch_setup_pdev_archdata(&pa->pdev); + strcpy(pa->payload, name); + platform_object_init(pa, pa->payload, id); } return pa ? &pa->pdev : NULL; @@ -213,6 +228,39 @@ struct platform_device *platform_device_alloc(const char *name, int id) EXPORT_SYMBOL_GPL(platform_device_alloc); /** + * platform_device_dmamask_alloc - create a platform device suitable to hold a dmamask + * @name: base name of the device we're adding + * @id: instance id + * + * Create a platform device object which can have other objects attached + * to it, and which will have attached objects freed when it is released. + */ +static struct platform_device *platform_device_dmamask_alloc(const char *name, + int id) +{ + struct platform_object *pa; + const size_t padding = (((offsetof(struct platform_object, payload) + + (__alignof__(u64) - 1)) & + ~(__alignof__(u64) - 1)) - + offsetof(struct platform_object, payload)); + + pa = platform_object_alloc(padding + sizeof(u64) + strlen(name) + 1); + if (pa) { + char *payload = pa->payload + padding; + /* + * Conceptually dma_mask in struct device should not be a pointer. + * See http://thread.gmane.org/gmane.linux.kernel.pci/9081 + */ + pa->pdev.dev.dma_mask = (void *)payload; + payload += sizeof(u64); + strcpy(payload, name); + platform_object_init(pa, payload, id); + } + + return pa ? &pa->pdev : NULL; +} + +/** * platform_device_add_resources - add resources to a platform device * @pdev: platform device allocated by platform_device_alloc to add resources to * @res: set of resources that needs to be allocated for the device @@ -427,7 +475,12 @@ struct platform_device *platform_device_register_full( int ret = -ENOMEM; struct platform_device *pdev; - pdev = platform_device_alloc(pdevinfo->name, pdevinfo->id); + if (!pdevinfo->dma_mask) + pdev = platform_device_alloc(pdevinfo->name, pdevinfo->id); + else + pdev = platform_device_dmamask_alloc(pdevinfo->name, + pdevinfo->id); + if (!pdev) goto err_alloc; @@ -435,17 +488,6 @@ struct platform_device *platform_device_register_full( ACPI_COMPANION_SET(&pdev->dev, pdevinfo->acpi_node.companion); if (pdevinfo->dma_mask) { - /* - * This memory isn't freed when the device is put, - * I don't have a nice idea for that though. Conceptually - * dma_mask in struct device should not be a pointer. - * See http://thread.gmane.org/gmane.linux.kernel.pci/9081 - */ - pdev->dev.dma_mask = - kmalloc(sizeof(*pdev->dev.dma_mask), GFP_KERNEL); - if (!pdev->dev.dma_mask) - goto err; - *pdev->dev.dma_mask = pdevinfo->dma_mask; pdev->dev.coherent_dma_mask = pdevinfo->dma_mask; } -- 1.8.4.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
