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![Linus Torvalds](/assets/img/avatar_default.png)
Here is the set of driver core and kernfs changes for 6.2-rc1. The "big" change in here is the addition of a new macro, container_of_const() that will preserve the "const-ness" of a pointer passed into it. The "problem" of the current container_of() macro is that if you pass in a "const *", out of it can comes a non-const pointer unless you specifically ask for it. For many usages, we want to preserve the "const" attribute by using the same call. For a specific example, this series changes the kobj_to_dev() macro to use it, allowing it to be used no matter what the const value is. This prevents every subsystem from having to declare 2 different individual macros (i.e. kobj_const_to_dev() and kobj_to_dev()) and having the compiler enforce the const value at build time, which having 2 macros would not do either. The driver for all of this have been discussions with the Rust kernel developers as to how to properly mark driver core, and kobject, objects as being "non-mutable". The changes to the kobject and driver core in this pull request are the result of that, as there are lots of paths where kobjects and device pointers are not modified at all, so marking them as "const" allows the compiler to enforce this. So, a nice side affect of the Rust development effort has been already to clean up the driver core code to be more obvious about object rules. All of this has been bike-shedded in quite a lot of detail on lkml with different names and implementations resulting in the tiny version we have in here, much better than my original proposal. Lots of subsystem maintainers have acked the changes as well. Other than this change, included in here are smaller stuff like: - kernfs fixes and updates to handle lock contention better - vmlinux.lds.h fixes and updates - sysfs and debugfs documentation updates - device property updates All of these have been in the linux-next tree for quite a while with no problems, OTHER than some merge issues with other trees that should be obvious when you hit them (block tree deletes a driver that this tree modifies, iommufd tree modifies code that this tree also touches). If there are merge problems with these trees, please let me know. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> -----BEGIN PGP SIGNATURE----- iG0EABECAC0WIQT0tgzFv3jCIUoxPcsxR9QN2y37KQUCY5wz3A8cZ3JlZ0Brcm9h aC5jb20ACgkQMUfUDdst+yks0ACeKYUlVgCsER8eYW+x18szFa2QTXgAn2h/VhZe 1Fp53boFaQkGBjl8mGF8 =v+FB -----END PGP SIGNATURE----- Merge tag 'driver-core-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core Pull driver core updates from Greg KH: "Here is the set of driver core and kernfs changes for 6.2-rc1. The "big" change in here is the addition of a new macro, container_of_const() that will preserve the "const-ness" of a pointer passed into it. The "problem" of the current container_of() macro is that if you pass in a "const *", out of it can comes a non-const pointer unless you specifically ask for it. For many usages, we want to preserve the "const" attribute by using the same call. For a specific example, this series changes the kobj_to_dev() macro to use it, allowing it to be used no matter what the const value is. This prevents every subsystem from having to declare 2 different individual macros (i.e. kobj_const_to_dev() and kobj_to_dev()) and having the compiler enforce the const value at build time, which having 2 macros would not do either. The driver for all of this have been discussions with the Rust kernel developers as to how to properly mark driver core, and kobject, objects as being "non-mutable". The changes to the kobject and driver core in this pull request are the result of that, as there are lots of paths where kobjects and device pointers are not modified at all, so marking them as "const" allows the compiler to enforce this. So, a nice side affect of the Rust development effort has been already to clean up the driver core code to be more obvious about object rules. All of this has been bike-shedded in quite a lot of detail on lkml with different names and implementations resulting in the tiny version we have in here, much better than my original proposal. Lots of subsystem maintainers have acked the changes as well. Other than this change, included in here are smaller stuff like: - kernfs fixes and updates to handle lock contention better - vmlinux.lds.h fixes and updates - sysfs and debugfs documentation updates - device property updates All of these have been in the linux-next tree for quite a while with no problems" * tag 'driver-core-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (58 commits) device property: Fix documentation for fwnode_get_next_parent() firmware_loader: fix up to_fw_sysfs() to preserve const usb.h: take advantage of container_of_const() device.h: move kobj_to_dev() to use container_of_const() container_of: add container_of_const() that preserves const-ness of the pointer driver core: fix up missed drivers/s390/char/hmcdrv_dev.c class.devnode() conversion. driver core: fix up missed scsi/cxlflash class.devnode() conversion. driver core: fix up some missing class.devnode() conversions. driver core: make struct class.devnode() take a const * driver core: make struct class.dev_uevent() take a const * cacheinfo: Remove of_node_put() for fw_token device property: Add a blank line in Kconfig of tests device property: Rename goto label to be more precise device property: Move PROPERTY_ENTRY_BOOL() a bit down device property: Get rid of __PROPERTY_ENTRY_ARRAY_EL*SIZE*() kernfs: fix all kernel-doc warnings and multiple typos driver core: pass a const * into of_device_uevent() kobject: kset_uevent_ops: make name() callback take a const * kobject: kset_uevent_ops: make filter() callback take a const * kobject: make kobject_namespace take a const * ...
326 lines
7.3 KiB
C
326 lines
7.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Framework for userspace DMA-BUF allocations
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*
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* Copyright (C) 2011 Google, Inc.
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* Copyright (C) 2019 Linaro Ltd.
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*/
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#include <linux/cdev.h>
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#include <linux/debugfs.h>
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#include <linux/device.h>
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#include <linux/dma-buf.h>
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#include <linux/err.h>
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#include <linux/xarray.h>
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#include <linux/list.h>
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#include <linux/slab.h>
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#include <linux/nospec.h>
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#include <linux/uaccess.h>
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#include <linux/syscalls.h>
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#include <linux/dma-heap.h>
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#include <uapi/linux/dma-heap.h>
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#define DEVNAME "dma_heap"
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#define NUM_HEAP_MINORS 128
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/**
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* struct dma_heap - represents a dmabuf heap in the system
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* @name: used for debugging/device-node name
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* @ops: ops struct for this heap
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* @heap_devt heap device node
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* @list list head connecting to list of heaps
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* @heap_cdev heap char device
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*
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* Represents a heap of memory from which buffers can be made.
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*/
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struct dma_heap {
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const char *name;
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const struct dma_heap_ops *ops;
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void *priv;
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dev_t heap_devt;
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struct list_head list;
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struct cdev heap_cdev;
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};
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static LIST_HEAD(heap_list);
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static DEFINE_MUTEX(heap_list_lock);
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static dev_t dma_heap_devt;
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static struct class *dma_heap_class;
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static DEFINE_XARRAY_ALLOC(dma_heap_minors);
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static int dma_heap_buffer_alloc(struct dma_heap *heap, size_t len,
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unsigned int fd_flags,
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unsigned int heap_flags)
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{
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struct dma_buf *dmabuf;
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int fd;
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/*
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* Allocations from all heaps have to begin
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* and end on page boundaries.
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*/
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len = PAGE_ALIGN(len);
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if (!len)
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return -EINVAL;
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dmabuf = heap->ops->allocate(heap, len, fd_flags, heap_flags);
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if (IS_ERR(dmabuf))
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return PTR_ERR(dmabuf);
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fd = dma_buf_fd(dmabuf, fd_flags);
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if (fd < 0) {
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dma_buf_put(dmabuf);
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/* just return, as put will call release and that will free */
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}
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return fd;
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}
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static int dma_heap_open(struct inode *inode, struct file *file)
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{
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struct dma_heap *heap;
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heap = xa_load(&dma_heap_minors, iminor(inode));
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if (!heap) {
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pr_err("dma_heap: minor %d unknown.\n", iminor(inode));
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return -ENODEV;
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}
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/* instance data as context */
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file->private_data = heap;
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nonseekable_open(inode, file);
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return 0;
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}
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static long dma_heap_ioctl_allocate(struct file *file, void *data)
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{
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struct dma_heap_allocation_data *heap_allocation = data;
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struct dma_heap *heap = file->private_data;
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int fd;
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if (heap_allocation->fd)
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return -EINVAL;
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if (heap_allocation->fd_flags & ~DMA_HEAP_VALID_FD_FLAGS)
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return -EINVAL;
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if (heap_allocation->heap_flags & ~DMA_HEAP_VALID_HEAP_FLAGS)
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return -EINVAL;
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fd = dma_heap_buffer_alloc(heap, heap_allocation->len,
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heap_allocation->fd_flags,
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heap_allocation->heap_flags);
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if (fd < 0)
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return fd;
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heap_allocation->fd = fd;
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return 0;
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}
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static unsigned int dma_heap_ioctl_cmds[] = {
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DMA_HEAP_IOCTL_ALLOC,
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};
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static long dma_heap_ioctl(struct file *file, unsigned int ucmd,
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unsigned long arg)
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{
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char stack_kdata[128];
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char *kdata = stack_kdata;
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unsigned int kcmd;
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unsigned int in_size, out_size, drv_size, ksize;
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int nr = _IOC_NR(ucmd);
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int ret = 0;
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if (nr >= ARRAY_SIZE(dma_heap_ioctl_cmds))
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return -EINVAL;
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nr = array_index_nospec(nr, ARRAY_SIZE(dma_heap_ioctl_cmds));
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/* Get the kernel ioctl cmd that matches */
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kcmd = dma_heap_ioctl_cmds[nr];
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/* Figure out the delta between user cmd size and kernel cmd size */
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drv_size = _IOC_SIZE(kcmd);
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out_size = _IOC_SIZE(ucmd);
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in_size = out_size;
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if ((ucmd & kcmd & IOC_IN) == 0)
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in_size = 0;
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if ((ucmd & kcmd & IOC_OUT) == 0)
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out_size = 0;
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ksize = max(max(in_size, out_size), drv_size);
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/* If necessary, allocate buffer for ioctl argument */
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if (ksize > sizeof(stack_kdata)) {
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kdata = kmalloc(ksize, GFP_KERNEL);
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if (!kdata)
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return -ENOMEM;
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}
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if (copy_from_user(kdata, (void __user *)arg, in_size) != 0) {
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ret = -EFAULT;
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goto err;
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}
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/* zero out any difference between the kernel/user structure size */
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if (ksize > in_size)
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memset(kdata + in_size, 0, ksize - in_size);
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switch (kcmd) {
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case DMA_HEAP_IOCTL_ALLOC:
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ret = dma_heap_ioctl_allocate(file, kdata);
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break;
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default:
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ret = -ENOTTY;
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goto err;
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}
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if (copy_to_user((void __user *)arg, kdata, out_size) != 0)
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ret = -EFAULT;
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err:
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if (kdata != stack_kdata)
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kfree(kdata);
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return ret;
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}
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static const struct file_operations dma_heap_fops = {
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.owner = THIS_MODULE,
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.open = dma_heap_open,
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.unlocked_ioctl = dma_heap_ioctl,
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#ifdef CONFIG_COMPAT
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.compat_ioctl = dma_heap_ioctl,
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#endif
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};
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/**
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* dma_heap_get_drvdata() - get per-subdriver data for the heap
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* @heap: DMA-Heap to retrieve private data for
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*
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* Returns:
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* The per-subdriver data for the heap.
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*/
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void *dma_heap_get_drvdata(struct dma_heap *heap)
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{
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return heap->priv;
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}
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/**
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* dma_heap_get_name() - get heap name
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* @heap: DMA-Heap to retrieve private data for
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*
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* Returns:
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* The char* for the heap name.
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*/
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const char *dma_heap_get_name(struct dma_heap *heap)
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{
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return heap->name;
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}
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struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
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{
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struct dma_heap *heap, *h, *err_ret;
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struct device *dev_ret;
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unsigned int minor;
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int ret;
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if (!exp_info->name || !strcmp(exp_info->name, "")) {
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pr_err("dma_heap: Cannot add heap without a name\n");
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return ERR_PTR(-EINVAL);
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}
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if (!exp_info->ops || !exp_info->ops->allocate) {
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pr_err("dma_heap: Cannot add heap with invalid ops struct\n");
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return ERR_PTR(-EINVAL);
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}
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heap = kzalloc(sizeof(*heap), GFP_KERNEL);
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if (!heap)
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return ERR_PTR(-ENOMEM);
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heap->name = exp_info->name;
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heap->ops = exp_info->ops;
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heap->priv = exp_info->priv;
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/* Find unused minor number */
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ret = xa_alloc(&dma_heap_minors, &minor, heap,
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XA_LIMIT(0, NUM_HEAP_MINORS - 1), GFP_KERNEL);
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if (ret < 0) {
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pr_err("dma_heap: Unable to get minor number for heap\n");
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err_ret = ERR_PTR(ret);
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goto err0;
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}
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/* Create device */
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heap->heap_devt = MKDEV(MAJOR(dma_heap_devt), minor);
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cdev_init(&heap->heap_cdev, &dma_heap_fops);
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ret = cdev_add(&heap->heap_cdev, heap->heap_devt, 1);
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if (ret < 0) {
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pr_err("dma_heap: Unable to add char device\n");
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err_ret = ERR_PTR(ret);
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goto err1;
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}
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dev_ret = device_create(dma_heap_class,
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NULL,
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heap->heap_devt,
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NULL,
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heap->name);
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if (IS_ERR(dev_ret)) {
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pr_err("dma_heap: Unable to create device\n");
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err_ret = ERR_CAST(dev_ret);
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goto err2;
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}
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mutex_lock(&heap_list_lock);
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/* check the name is unique */
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list_for_each_entry(h, &heap_list, list) {
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if (!strcmp(h->name, exp_info->name)) {
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mutex_unlock(&heap_list_lock);
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pr_err("dma_heap: Already registered heap named %s\n",
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exp_info->name);
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err_ret = ERR_PTR(-EINVAL);
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goto err3;
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}
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}
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/* Add heap to the list */
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list_add(&heap->list, &heap_list);
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mutex_unlock(&heap_list_lock);
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return heap;
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err3:
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device_destroy(dma_heap_class, heap->heap_devt);
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err2:
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cdev_del(&heap->heap_cdev);
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err1:
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xa_erase(&dma_heap_minors, minor);
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err0:
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kfree(heap);
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return err_ret;
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}
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static char *dma_heap_devnode(const struct device *dev, umode_t *mode)
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{
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return kasprintf(GFP_KERNEL, "dma_heap/%s", dev_name(dev));
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}
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static int dma_heap_init(void)
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{
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int ret;
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ret = alloc_chrdev_region(&dma_heap_devt, 0, NUM_HEAP_MINORS, DEVNAME);
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if (ret)
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return ret;
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dma_heap_class = class_create(THIS_MODULE, DEVNAME);
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if (IS_ERR(dma_heap_class)) {
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unregister_chrdev_region(dma_heap_devt, NUM_HEAP_MINORS);
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return PTR_ERR(dma_heap_class);
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}
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dma_heap_class->devnode = dma_heap_devnode;
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return 0;
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}
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subsys_initcall(dma_heap_init);
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