| /* |
| * Public API and common code for kernel->userspace relay file support. |
| * |
| * See Documentation/filesystems/relay.rst for an overview. |
| * |
| * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp |
| * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com) |
| * |
| * Moved to kernel/relay.c by Paul Mundt, 2006. |
| * November 2006 - CPU hotplug support by Mathieu Desnoyers |
| * (mathieu.desnoyers@polymtl.ca) |
| * |
| * This file is released under the GPL. |
| */ |
| #include <linux/errno.h> |
| #include <linux/stddef.h> |
| #include <linux/slab.h> |
| #include <linux/export.h> |
| #include <linux/string.h> |
| #include <linux/relay.h> |
| #include <linux/vmalloc.h> |
| #include <linux/mm.h> |
| #include <linux/cpu.h> |
| #include <linux/splice.h> |
| |
| /* list of open channels, for cpu hotplug */ |
| static DEFINE_MUTEX(relay_channels_mutex); |
| static LIST_HEAD(relay_channels); |
| |
| /* |
| * fault() vm_op implementation for relay file mapping. |
| */ |
| static vm_fault_t relay_buf_fault(struct vm_fault *vmf) |
| { |
| struct page *page; |
| struct rchan_buf *buf = vmf->vma->vm_private_data; |
| pgoff_t pgoff = vmf->pgoff; |
| |
| if (!buf) |
| return VM_FAULT_OOM; |
| |
| page = vmalloc_to_page(buf->start + (pgoff << PAGE_SHIFT)); |
| if (!page) |
| return VM_FAULT_SIGBUS; |
| get_page(page); |
| vmf->page = page; |
| |
| return 0; |
| } |
| |
| /* |
| * vm_ops for relay file mappings. |
| */ |
| static const struct vm_operations_struct relay_file_mmap_ops = { |
| .fault = relay_buf_fault, |
| }; |
| |
| /* |
| * allocate an array of pointers of struct page |
| */ |
| static struct page **relay_alloc_page_array(unsigned int n_pages) |
| { |
| return kvcalloc(n_pages, sizeof(struct page *), GFP_KERNEL); |
| } |
| |
| /* |
| * free an array of pointers of struct page |
| */ |
| static void relay_free_page_array(struct page **array) |
| { |
| kvfree(array); |
| } |
| |
| /** |
| * relay_mmap_buf: - mmap channel buffer to process address space |
| * @buf: relay channel buffer |
| * @vma: vm_area_struct describing memory to be mapped |
| * |
| * Returns 0 if ok, negative on error |
| * |
| * Caller should already have grabbed mmap_lock. |
| */ |
| static int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma) |
| { |
| unsigned long length = vma->vm_end - vma->vm_start; |
| |
| if (!buf) |
| return -EBADF; |
| |
| if (length != (unsigned long)buf->chan->alloc_size) |
| return -EINVAL; |
| |
| vma->vm_ops = &relay_file_mmap_ops; |
| vma->vm_flags |= VM_DONTEXPAND; |
| vma->vm_private_data = buf; |
| |
| return 0; |
| } |
| |
| /** |
| * relay_alloc_buf - allocate a channel buffer |
| * @buf: the buffer struct |
| * @size: total size of the buffer |
| * |
| * Returns a pointer to the resulting buffer, %NULL if unsuccessful. The |
| * passed in size will get page aligned, if it isn't already. |
| */ |
| static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size) |
| { |
| void *mem; |
| unsigned int i, j, n_pages; |
| |
| *size = PAGE_ALIGN(*size); |
| n_pages = *size >> PAGE_SHIFT; |
| |
| buf->page_array = relay_alloc_page_array(n_pages); |
| if (!buf->page_array) |
| return NULL; |
| |
| for (i = 0; i < n_pages; i++) { |
| buf->page_array[i] = alloc_page(GFP_KERNEL); |
| if (unlikely(!buf->page_array[i])) |
| goto depopulate; |
| set_page_private(buf->page_array[i], (unsigned long)buf); |
| } |
| mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL); |
| if (!mem) |
| goto depopulate; |
| |
| memset(mem, 0, *size); |
| buf->page_count = n_pages; |
| return mem; |
| |
| depopulate: |
| for (j = 0; j < i; j++) |
| __free_page(buf->page_array[j]); |
| relay_free_page_array(buf->page_array); |
| return NULL; |
| } |
| |
| /** |
| * relay_create_buf - allocate and initialize a channel buffer |
| * @chan: the relay channel |
| * |
| * Returns channel buffer if successful, %NULL otherwise. |
| */ |
| static struct rchan_buf *relay_create_buf(struct rchan *chan) |
| { |
| struct rchan_buf *buf; |
| |
| if (chan->n_subbufs > KMALLOC_MAX_SIZE / sizeof(size_t)) |
| return NULL; |
| |
| buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL); |
| if (!buf) |
| return NULL; |
| buf->padding = kmalloc_array(chan->n_subbufs, sizeof(size_t), |
| GFP_KERNEL); |
| if (!buf->padding) |
| goto free_buf; |
| |
| buf->start = relay_alloc_buf(buf, &chan->alloc_size); |
| if (!buf->start) |
| goto free_buf; |
| |
| buf->chan = chan; |
| kref_get(&buf->chan->kref); |
| return buf; |
| |
| free_buf: |
| kfree(buf->padding); |
| kfree(buf); |
| return NULL; |
| } |
| |
| /** |
| * relay_destroy_channel - free the channel struct |
| * @kref: target kernel reference that contains the relay channel |
| * |
| * Should only be called from kref_put(). |
| */ |
| static void relay_destroy_channel(struct kref *kref) |
| { |
| struct rchan *chan = container_of(kref, struct rchan, kref); |
| free_percpu(chan->buf); |
| kfree(chan); |
| } |
| |
| /** |
| * relay_destroy_buf - destroy an rchan_buf struct and associated buffer |
| * @buf: the buffer struct |
| */ |
| static void relay_destroy_buf(struct rchan_buf *buf) |
| { |
| struct rchan *chan = buf->chan; |
| unsigned int i; |
| |
| if (likely(buf->start)) { |
| vunmap(buf->start); |
| for (i = 0; i < buf->page_count; i++) |
| __free_page(buf->page_array[i]); |
| relay_free_page_array(buf->page_array); |
| } |
| *per_cpu_ptr(chan->buf, buf->cpu) = NULL; |
| kfree(buf->padding); |
| kfree(buf); |
| kref_put(&chan->kref, relay_destroy_channel); |
| } |
| |
| /** |
| * relay_remove_buf - remove a channel buffer |
| * @kref: target kernel reference that contains the relay buffer |
| * |
| * Removes the file from the filesystem, which also frees the |
| * rchan_buf_struct and the channel buffer. Should only be called from |
| * kref_put(). |
| */ |
| static void relay_remove_buf(struct kref *kref) |
| { |
| struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref); |
| relay_destroy_buf(buf); |
| } |
| |
| /** |
| * relay_buf_empty - boolean, is the channel buffer empty? |
| * @buf: channel buffer |
| * |
| * Returns 1 if the buffer is empty, 0 otherwise. |
| */ |
| static int relay_buf_empty(struct rchan_buf *buf) |
| { |
| return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1; |
| } |
| |
| /** |
| * relay_buf_full - boolean, is the channel buffer full? |
| * @buf: channel buffer |
| * |
| * Returns 1 if the buffer is full, 0 otherwise. |
| */ |
| int relay_buf_full(struct rchan_buf *buf) |
| { |
| size_t ready = buf->subbufs_produced - buf->subbufs_consumed; |
| return (ready >= buf->chan->n_subbufs) ? 1 : 0; |
| } |
| EXPORT_SYMBOL_GPL(relay_buf_full); |
| |
| /* |
| * High-level relay kernel API and associated functions. |
| */ |
| |
| static int relay_subbuf_start(struct rchan_buf *buf, void *subbuf, |
| void *prev_subbuf, size_t prev_padding) |
| { |
| if (!buf->chan->cb->subbuf_start) |
| return !relay_buf_full(buf); |
| |
| return buf->chan->cb->subbuf_start(buf, subbuf, |
| prev_subbuf, prev_padding); |
| } |
| |
| /** |
| * wakeup_readers - wake up readers waiting on a channel |
| * @work: contains the channel buffer |
| * |
| * This is the function used to defer reader waking |
| */ |
| static void wakeup_readers(struct irq_work *work) |
| { |
| struct rchan_buf *buf; |
| |
| buf = container_of(work, struct rchan_buf, wakeup_work); |
| wake_up_interruptible(&buf->read_wait); |
| } |
| |
| /** |
| * __relay_reset - reset a channel buffer |
| * @buf: the channel buffer |
| * @init: 1 if this is a first-time initialization |
| * |
| * See relay_reset() for description of effect. |
| */ |
| static void __relay_reset(struct rchan_buf *buf, unsigned int init) |
| { |
| size_t i; |
| |
| if (init) { |
| init_waitqueue_head(&buf->read_wait); |
| kref_init(&buf->kref); |
| init_irq_work(&buf->wakeup_work, wakeup_readers); |
| } else { |
| irq_work_sync(&buf->wakeup_work); |
| } |
| |
| buf->subbufs_produced = 0; |
| buf->subbufs_consumed = 0; |
| buf->bytes_consumed = 0; |
| buf->finalized = 0; |
| buf->data = buf->start; |
| buf->offset = 0; |
| |
| for (i = 0; i < buf->chan->n_subbufs; i++) |
| buf->padding[i] = 0; |
| |
| relay_subbuf_start(buf, buf->data, NULL, 0); |
| } |
| |
| /** |
| * relay_reset - reset the channel |
| * @chan: the channel |
| * |
| * This has the effect of erasing all data from all channel buffers |
| * and restarting the channel in its initial state. The buffers |
| * are not freed, so any mappings are still in effect. |
| * |
| * NOTE. Care should be taken that the channel isn't actually |
| * being used by anything when this call is made. |
| */ |
| void relay_reset(struct rchan *chan) |
| { |
| struct rchan_buf *buf; |
| unsigned int i; |
| |
| if (!chan) |
| return; |
| |
| if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) { |
| __relay_reset(buf, 0); |
| return; |
| } |
| |
| mutex_lock(&relay_channels_mutex); |
| for_each_possible_cpu(i) |
| if ((buf = *per_cpu_ptr(chan->buf, i))) |
| __relay_reset(buf, 0); |
| mutex_unlock(&relay_channels_mutex); |
| } |
| EXPORT_SYMBOL_GPL(relay_reset); |
| |
| static inline void relay_set_buf_dentry(struct rchan_buf *buf, |
| struct dentry *dentry) |
| { |
| buf->dentry = dentry; |
| d_inode(buf->dentry)->i_size = buf->early_bytes; |
| } |
| |
| static struct dentry *relay_create_buf_file(struct rchan *chan, |
| struct rchan_buf *buf, |
| unsigned int cpu) |
| { |
| struct dentry *dentry; |
| char *tmpname; |
| |
| tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL); |
| if (!tmpname) |
| return NULL; |
| snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu); |
| |
| /* Create file in fs */ |
| dentry = chan->cb->create_buf_file(tmpname, chan->parent, |
| S_IRUSR, buf, |
| &chan->is_global); |
| if (IS_ERR(dentry)) |
| dentry = NULL; |
| |
| kfree(tmpname); |
| |
| return dentry; |
| } |
| |
| /* |
| * relay_open_buf - create a new relay channel buffer |
| * |
| * used by relay_open() and CPU hotplug. |
| */ |
| static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu) |
| { |
| struct rchan_buf *buf = NULL; |
| struct dentry *dentry; |
| |
| if (chan->is_global) |
| return *per_cpu_ptr(chan->buf, 0); |
| |
| buf = relay_create_buf(chan); |
| if (!buf) |
| return NULL; |
| |
| if (chan->has_base_filename) { |
| dentry = relay_create_buf_file(chan, buf, cpu); |
| if (!dentry) |
| goto free_buf; |
| relay_set_buf_dentry(buf, dentry); |
| } else { |
| /* Only retrieve global info, nothing more, nothing less */ |
| dentry = chan->cb->create_buf_file(NULL, NULL, |
| S_IRUSR, buf, |
| &chan->is_global); |
| if (IS_ERR_OR_NULL(dentry)) |
| goto free_buf; |
| } |
| |
| buf->cpu = cpu; |
| __relay_reset(buf, 1); |
| |
| if(chan->is_global) { |
| *per_cpu_ptr(chan->buf, 0) = buf; |
| buf->cpu = 0; |
| } |
| |
| return buf; |
| |
| free_buf: |
| relay_destroy_buf(buf); |
| return NULL; |
| } |
| |
| /** |
| * relay_close_buf - close a channel buffer |
| * @buf: channel buffer |
| * |
| * Marks the buffer finalized and restores the default callbacks. |
| * The channel buffer and channel buffer data structure are then freed |
| * automatically when the last reference is given up. |
| */ |
| static void relay_close_buf(struct rchan_buf *buf) |
| { |
| buf->finalized = 1; |
| irq_work_sync(&buf->wakeup_work); |
| buf->chan->cb->remove_buf_file(buf->dentry); |
| kref_put(&buf->kref, relay_remove_buf); |
| } |
| |
| int relay_prepare_cpu(unsigned int cpu) |
| { |
| struct rchan *chan; |
| struct rchan_buf *buf; |
| |
| mutex_lock(&relay_channels_mutex); |
| list_for_each_entry(chan, &relay_channels, list) { |
| if (*per_cpu_ptr(chan->buf, cpu)) |
| continue; |
| buf = relay_open_buf(chan, cpu); |
| if (!buf) { |
| pr_err("relay: cpu %d buffer creation failed\n", cpu); |
| mutex_unlock(&relay_channels_mutex); |
| return -ENOMEM; |
| } |
| *per_cpu_ptr(chan->buf, cpu) = buf; |
| } |
| mutex_unlock(&relay_channels_mutex); |
| return 0; |
| } |
| |
| /** |
| * relay_open - create a new relay channel |
| * @base_filename: base name of files to create, %NULL for buffering only |
| * @parent: dentry of parent directory, %NULL for root directory or buffer |
| * @subbuf_size: size of sub-buffers |
| * @n_subbufs: number of sub-buffers |
| * @cb: client callback functions |
| * @private_data: user-defined data |
| * |
| * Returns channel pointer if successful, %NULL otherwise. |
| * |
| * Creates a channel buffer for each cpu using the sizes and |
| * attributes specified. The created channel buffer files |
| * will be named base_filename0...base_filenameN-1. File |
| * permissions will be %S_IRUSR. |
| * |
| * If opening a buffer (@parent = NULL) that you later wish to register |
| * in a filesystem, call relay_late_setup_files() once the @parent dentry |
| * is available. |
| */ |
| struct rchan *relay_open(const char *base_filename, |
| struct dentry *parent, |
| size_t subbuf_size, |
| size_t n_subbufs, |
| const struct rchan_callbacks *cb, |
| void *private_data) |
| { |
| unsigned int i; |
| struct rchan *chan; |
| struct rchan_buf *buf; |
| |
| if (!(subbuf_size && n_subbufs)) |
| return NULL; |
| if (subbuf_size > UINT_MAX / n_subbufs) |
| return NULL; |
| if (!cb || !cb->create_buf_file || !cb->remove_buf_file) |
| return NULL; |
| |
| chan = kzalloc(sizeof(struct rchan), GFP_KERNEL); |
| if (!chan) |
| return NULL; |
| |
| chan->buf = alloc_percpu(struct rchan_buf *); |
| if (!chan->buf) { |
| kfree(chan); |
| return NULL; |
| } |
| |
| chan->version = RELAYFS_CHANNEL_VERSION; |
| chan->n_subbufs = n_subbufs; |
| chan->subbuf_size = subbuf_size; |
| chan->alloc_size = PAGE_ALIGN(subbuf_size * n_subbufs); |
| chan->parent = parent; |
| chan->private_data = private_data; |
| if (base_filename) { |
| chan->has_base_filename = 1; |
| strlcpy(chan->base_filename, base_filename, NAME_MAX); |
| } |
| chan->cb = cb; |
| kref_init(&chan->kref); |
| |
| mutex_lock(&relay_channels_mutex); |
| for_each_online_cpu(i) { |
| buf = relay_open_buf(chan, i); |
| if (!buf) |
| goto free_bufs; |
| *per_cpu_ptr(chan->buf, i) = buf; |
| } |
| list_add(&chan->list, &relay_channels); |
| mutex_unlock(&relay_channels_mutex); |
| |
| return chan; |
| |
| free_bufs: |
| for_each_possible_cpu(i) { |
| if ((buf = *per_cpu_ptr(chan->buf, i))) |
| relay_close_buf(buf); |
| } |
| |
| kref_put(&chan->kref, relay_destroy_channel); |
| mutex_unlock(&relay_channels_mutex); |
| return NULL; |
| } |
| EXPORT_SYMBOL_GPL(relay_open); |
| |
| struct rchan_percpu_buf_dispatcher { |
| struct rchan_buf *buf; |
| struct dentry *dentry; |
| }; |
| |
| /* Called in atomic context. */ |
| static void __relay_set_buf_dentry(void *info) |
| { |
| struct rchan_percpu_buf_dispatcher *p = info; |
| |
| relay_set_buf_dentry(p->buf, p->dentry); |
| } |
| |
| /** |
| * relay_late_setup_files - triggers file creation |
| * @chan: channel to operate on |
| * @base_filename: base name of files to create |
| * @parent: dentry of parent directory, %NULL for root directory |
| * |
| * Returns 0 if successful, non-zero otherwise. |
| * |
| * Use to setup files for a previously buffer-only channel created |
| * by relay_open() with a NULL parent dentry. |
| * |
| * For example, this is useful for perfomring early tracing in kernel, |
| * before VFS is up and then exposing the early results once the dentry |
| * is available. |
| */ |
| int relay_late_setup_files(struct rchan *chan, |
| const char *base_filename, |
| struct dentry *parent) |
| { |
| int err = 0; |
| unsigned int i, curr_cpu; |
| unsigned long flags; |
| struct dentry *dentry; |
| struct rchan_buf *buf; |
| struct rchan_percpu_buf_dispatcher disp; |
| |
| if (!chan || !base_filename) |
| return -EINVAL; |
| |
| strlcpy(chan->base_filename, base_filename, NAME_MAX); |
| |
| mutex_lock(&relay_channels_mutex); |
| /* Is chan already set up? */ |
| if (unlikely(chan->has_base_filename)) { |
| mutex_unlock(&relay_channels_mutex); |
| return -EEXIST; |
| } |
| chan->has_base_filename = 1; |
| chan->parent = parent; |
| |
| if (chan->is_global) { |
| err = -EINVAL; |
| buf = *per_cpu_ptr(chan->buf, 0); |
| if (!WARN_ON_ONCE(!buf)) { |
| dentry = relay_create_buf_file(chan, buf, 0); |
| if (dentry && !WARN_ON_ONCE(!chan->is_global)) { |
| relay_set_buf_dentry(buf, dentry); |
| err = 0; |
| } |
| } |
| mutex_unlock(&relay_channels_mutex); |
| return err; |
| } |
| |
| curr_cpu = get_cpu(); |
| /* |
| * The CPU hotplug notifier ran before us and created buffers with |
| * no files associated. So it's safe to call relay_setup_buf_file() |
| * on all currently online CPUs. |
| */ |
| for_each_online_cpu(i) { |
| buf = *per_cpu_ptr(chan->buf, i); |
| if (unlikely(!buf)) { |
| WARN_ONCE(1, KERN_ERR "CPU has no buffer!\n"); |
| err = -EINVAL; |
| break; |
| } |
| |
| dentry = relay_create_buf_file(chan, buf, i); |
| if (unlikely(!dentry)) { |
| err = -EINVAL; |
| break; |
| } |
| |
| if (curr_cpu == i) { |
| local_irq_save(flags); |
| relay_set_buf_dentry(buf, dentry); |
| local_irq_restore(flags); |
| } else { |
| disp.buf = buf; |
| disp.dentry = dentry; |
| smp_mb(); |
| /* relay_channels_mutex must be held, so wait. */ |
| err = smp_call_function_single(i, |
| __relay_set_buf_dentry, |
| &disp, 1); |
| } |
| if (unlikely(err)) |
| break; |
| } |
| put_cpu(); |
| mutex_unlock(&relay_channels_mutex); |
| |
| return err; |
| } |
| EXPORT_SYMBOL_GPL(relay_late_setup_files); |
| |
| /** |
| * relay_switch_subbuf - switch to a new sub-buffer |
| * @buf: channel buffer |
| * @length: size of current event |
| * |
| * Returns either the length passed in or 0 if full. |
| * |
| * Performs sub-buffer-switch tasks such as invoking callbacks, |
| * updating padding counts, waking up readers, etc. |
| */ |
| size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) |
| { |
| void *old, *new; |
| size_t old_subbuf, new_subbuf; |
| |
| if (unlikely(length > buf->chan->subbuf_size)) |
| goto toobig; |
| |
| if (buf->offset != buf->chan->subbuf_size + 1) { |
| buf->prev_padding = buf->chan->subbuf_size - buf->offset; |
| old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; |
| buf->padding[old_subbuf] = buf->prev_padding; |
| buf->subbufs_produced++; |
| if (buf->dentry) |
| d_inode(buf->dentry)->i_size += |
| buf->chan->subbuf_size - |
| buf->padding[old_subbuf]; |
| else |
| buf->early_bytes += buf->chan->subbuf_size - |
| buf->padding[old_subbuf]; |
| smp_mb(); |
| if (waitqueue_active(&buf->read_wait)) { |
| /* |
| * Calling wake_up_interruptible() from here |
| * will deadlock if we happen to be logging |
| * from the scheduler (trying to re-grab |
| * rq->lock), so defer it. |
| */ |
| irq_work_queue(&buf->wakeup_work); |
| } |
| } |
| |
| old = buf->data; |
| new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; |
| new = buf->start + new_subbuf * buf->chan->subbuf_size; |
| buf->offset = 0; |
| if (!relay_subbuf_start(buf, new, old, buf->prev_padding)) { |
| buf->offset = buf->chan->subbuf_size + 1; |
| return 0; |
| } |
| buf->data = new; |
| buf->padding[new_subbuf] = 0; |
| |
| if (unlikely(length + buf->offset > buf->chan->subbuf_size)) |
| goto toobig; |
| |
| return length; |
| |
| toobig: |
| buf->chan->last_toobig = length; |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(relay_switch_subbuf); |
| |
| /** |
| * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count |
| * @chan: the channel |
| * @cpu: the cpu associated with the channel buffer to update |
| * @subbufs_consumed: number of sub-buffers to add to current buf's count |
| * |
| * Adds to the channel buffer's consumed sub-buffer count. |
| * subbufs_consumed should be the number of sub-buffers newly consumed, |
| * not the total consumed. |
| * |
| * NOTE. Kernel clients don't need to call this function if the channel |
| * mode is 'overwrite'. |
| */ |
| void relay_subbufs_consumed(struct rchan *chan, |
| unsigned int cpu, |
| size_t subbufs_consumed) |
| { |
| struct rchan_buf *buf; |
| |
| if (!chan || cpu >= NR_CPUS) |
| return; |
| |
| buf = *per_cpu_ptr(chan->buf, cpu); |
| if (!buf || subbufs_consumed > chan->n_subbufs) |
| return; |
| |
| if (subbufs_consumed > buf->subbufs_produced - buf->subbufs_consumed) |
| buf->subbufs_consumed = buf->subbufs_produced; |
| else |
| buf->subbufs_consumed += subbufs_consumed; |
| } |
| EXPORT_SYMBOL_GPL(relay_subbufs_consumed); |
| |
| /** |
| * relay_close - close the channel |
| * @chan: the channel |
| * |
| * Closes all channel buffers and frees the channel. |
| */ |
| void relay_close(struct rchan *chan) |
| { |
| struct rchan_buf *buf; |
| unsigned int i; |
| |
| if (!chan) |
| return; |
| |
| mutex_lock(&relay_channels_mutex); |
| if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) |
| relay_close_buf(buf); |
| else |
| for_each_possible_cpu(i) |
| if ((buf = *per_cpu_ptr(chan->buf, i))) |
| relay_close_buf(buf); |
| |
| if (chan->last_toobig) |
| printk(KERN_WARNING "relay: one or more items not logged " |
| "[item size (%zd) > sub-buffer size (%zd)]\n", |
| chan->last_toobig, chan->subbuf_size); |
| |
| list_del(&chan->list); |
| kref_put(&chan->kref, relay_destroy_channel); |
| mutex_unlock(&relay_channels_mutex); |
| } |
| EXPORT_SYMBOL_GPL(relay_close); |
| |
| /** |
| * relay_flush - close the channel |
| * @chan: the channel |
| * |
| * Flushes all channel buffers, i.e. forces buffer switch. |
| */ |
| void relay_flush(struct rchan *chan) |
| { |
| struct rchan_buf *buf; |
| unsigned int i; |
| |
| if (!chan) |
| return; |
| |
| if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) { |
| relay_switch_subbuf(buf, 0); |
| return; |
| } |
| |
| mutex_lock(&relay_channels_mutex); |
| for_each_possible_cpu(i) |
| if ((buf = *per_cpu_ptr(chan->buf, i))) |
| relay_switch_subbuf(buf, 0); |
| mutex_unlock(&relay_channels_mutex); |
| } |
| EXPORT_SYMBOL_GPL(relay_flush); |
| |
| /** |
| * relay_file_open - open file op for relay files |
| * @inode: the inode |
| * @filp: the file |
| * |
| * Increments the channel buffer refcount. |
| */ |
| static int relay_file_open(struct inode *inode, struct file *filp) |
| { |
| struct rchan_buf *buf = inode->i_private; |
| kref_get(&buf->kref); |
| filp->private_data = buf; |
| |
| return nonseekable_open(inode, filp); |
| } |
| |
| /** |
| * relay_file_mmap - mmap file op for relay files |
| * @filp: the file |
| * @vma: the vma describing what to map |
| * |
| * Calls upon relay_mmap_buf() to map the file into user space. |
| */ |
| static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma) |
| { |
| struct rchan_buf *buf = filp->private_data; |
| return relay_mmap_buf(buf, vma); |
| } |
| |
| /** |
| * relay_file_poll - poll file op for relay files |
| * @filp: the file |
| * @wait: poll table |
| * |
| * Poll implemention. |
| */ |
| static __poll_t relay_file_poll(struct file *filp, poll_table *wait) |
| { |
| __poll_t mask = 0; |
| struct rchan_buf *buf = filp->private_data; |
| |
| if (buf->finalized) |
| return EPOLLERR; |
| |
| if (filp->f_mode & FMODE_READ) { |
| poll_wait(filp, &buf->read_wait, wait); |
| if (!relay_buf_empty(buf)) |
| mask |= EPOLLIN | EPOLLRDNORM; |
| } |
| |
| return mask; |
| } |
| |
| /** |
| * relay_file_release - release file op for relay files |
| * @inode: the inode |
| * @filp: the file |
| * |
| * Decrements the channel refcount, as the filesystem is |
| * no longer using it. |
| */ |
| static int relay_file_release(struct inode *inode, struct file *filp) |
| { |
| struct rchan_buf *buf = filp->private_data; |
| kref_put(&buf->kref, relay_remove_buf); |
| |
| return 0; |
| } |
| |
| /* |
| * relay_file_read_consume - update the consumed count for the buffer |
| */ |
| static void relay_file_read_consume(struct rchan_buf *buf, |
| size_t read_pos, |
| size_t bytes_consumed) |
| { |
| size_t subbuf_size = buf->chan->subbuf_size; |
| size_t n_subbufs = buf->chan->n_subbufs; |
| size_t read_subbuf; |
| |
| if (buf->subbufs_produced == buf->subbufs_consumed && |
| buf->offset == buf->bytes_consumed) |
| return; |
| |
| if (buf->bytes_consumed + bytes_consumed > subbuf_size) { |
| relay_subbufs_consumed(buf->chan, buf->cpu, 1); |
| buf->bytes_consumed = 0; |
| } |
| |
| buf->bytes_consumed += bytes_consumed; |
| if (!read_pos) |
| read_subbuf = buf->subbufs_consumed % n_subbufs; |
| else |
| read_subbuf = read_pos / buf->chan->subbuf_size; |
| if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) { |
| if ((read_subbuf == buf->subbufs_produced % n_subbufs) && |
| (buf->offset == subbuf_size)) |
| return; |
| relay_subbufs_consumed(buf->chan, buf->cpu, 1); |
| buf->bytes_consumed = 0; |
| } |
| } |
| |
| /* |
| * relay_file_read_avail - boolean, are there unconsumed bytes available? |
| */ |
| static int relay_file_read_avail(struct rchan_buf *buf) |
| { |
| size_t subbuf_size = buf->chan->subbuf_size; |
| size_t n_subbufs = buf->chan->n_subbufs; |
| size_t produced = buf->subbufs_produced; |
| size_t consumed; |
| |
| relay_file_read_consume(buf, 0, 0); |
| |
| consumed = buf->subbufs_consumed; |
| |
| if (unlikely(buf->offset > subbuf_size)) { |
| if (produced == consumed) |
| return 0; |
| return 1; |
| } |
| |
| if (unlikely(produced - consumed >= n_subbufs)) { |
| consumed = produced - n_subbufs + 1; |
| buf->subbufs_consumed = consumed; |
| buf->bytes_consumed = 0; |
| } |
| |
| produced = (produced % n_subbufs) * subbuf_size + buf->offset; |
| consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed; |
| |
| if (consumed > produced) |
| produced += n_subbufs * subbuf_size; |
| |
| if (consumed == produced) { |
| if (buf->offset == subbuf_size && |
| buf->subbufs_produced > buf->subbufs_consumed) |
| return 1; |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| /** |
| * relay_file_read_subbuf_avail - return bytes available in sub-buffer |
| * @read_pos: file read position |
| * @buf: relay channel buffer |
| */ |
| static size_t relay_file_read_subbuf_avail(size_t read_pos, |
| struct rchan_buf *buf) |
| { |
| size_t padding, avail = 0; |
| size_t read_subbuf, read_offset, write_subbuf, write_offset; |
| size_t subbuf_size = buf->chan->subbuf_size; |
| |
| write_subbuf = (buf->data - buf->start) / subbuf_size; |
| write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; |
| read_subbuf = read_pos / subbuf_size; |
| read_offset = read_pos % subbuf_size; |
| padding = buf->padding[read_subbuf]; |
| |
| if (read_subbuf == write_subbuf) { |
| if (read_offset + padding < write_offset) |
| avail = write_offset - (read_offset + padding); |
| } else |
| avail = (subbuf_size - padding) - read_offset; |
| |
| return avail; |
| } |
| |
| /** |
| * relay_file_read_start_pos - find the first available byte to read |
| * @buf: relay channel buffer |
| * |
| * If the read_pos is in the middle of padding, return the |
| * position of the first actually available byte, otherwise |
| * return the original value. |
| */ |
| static size_t relay_file_read_start_pos(struct rchan_buf *buf) |
| { |
| size_t read_subbuf, padding, padding_start, padding_end; |
| size_t subbuf_size = buf->chan->subbuf_size; |
| size_t n_subbufs = buf->chan->n_subbufs; |
| size_t consumed = buf->subbufs_consumed % n_subbufs; |
| size_t read_pos = (consumed * subbuf_size + buf->bytes_consumed) |
| % (n_subbufs * subbuf_size); |
| |
| read_subbuf = read_pos / subbuf_size; |
| padding = buf->padding[read_subbuf]; |
| padding_start = (read_subbuf + 1) * subbuf_size - padding; |
| padding_end = (read_subbuf + 1) * subbuf_size; |
| if (read_pos >= padding_start && read_pos < padding_end) { |
| read_subbuf = (read_subbuf + 1) % n_subbufs; |
| read_pos = read_subbuf * subbuf_size; |
| } |
| |
| return read_pos; |
| } |
| |
| /** |
| * relay_file_read_end_pos - return the new read position |
| * @read_pos: file read position |
| * @buf: relay channel buffer |
| * @count: number of bytes to be read |
| */ |
| static size_t relay_file_read_end_pos(struct rchan_buf *buf, |
| size_t read_pos, |
| size_t count) |
| { |
| size_t read_subbuf, padding, end_pos; |
| size_t subbuf_size = buf->chan->subbuf_size; |
| size_t n_subbufs = buf->chan->n_subbufs; |
| |
| read_subbuf = read_pos / subbuf_size; |
| padding = buf->padding[read_subbuf]; |
| if (read_pos % subbuf_size + count + padding == subbuf_size) |
| end_pos = (read_subbuf + 1) * subbuf_size; |
| else |
| end_pos = read_pos + count; |
| if (end_pos >= subbuf_size * n_subbufs) |
| end_pos = 0; |
| |
| return end_pos; |
| } |
| |
| static ssize_t relay_file_read(struct file *filp, |
| char __user *buffer, |
| size_t count, |
| loff_t *ppos) |
| { |
| struct rchan_buf *buf = filp->private_data; |
| size_t read_start, avail; |
| size_t written = 0; |
| int ret; |
| |
| if (!count) |
| return 0; |
| |
| inode_lock(file_inode(filp)); |
| do { |
| void *from; |
| |
| if (!relay_file_read_avail(buf)) |
| break; |
| |
| read_start = relay_file_read_start_pos(buf); |
| avail = relay_file_read_subbuf_avail(read_start, buf); |
| if (!avail) |
| break; |
| |
| avail = min(count, avail); |
| from = buf->start + read_start; |
| ret = avail; |
| if (copy_to_user(buffer, from, avail)) |
| break; |
| |
| buffer += ret; |
| written += ret; |
| count -= ret; |
| |
| relay_file_read_consume(buf, read_start, ret); |
| *ppos = relay_file_read_end_pos(buf, read_start, ret); |
| } while (count); |
| inode_unlock(file_inode(filp)); |
| |
| return written; |
| } |
| |
| static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed) |
| { |
| rbuf->bytes_consumed += bytes_consumed; |
| |
| if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) { |
| relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1); |
| rbuf->bytes_consumed %= rbuf->chan->subbuf_size; |
| } |
| } |
| |
| static void relay_pipe_buf_release(struct pipe_inode_info *pipe, |
| struct pipe_buffer *buf) |
| { |
| struct rchan_buf *rbuf; |
| |
| rbuf = (struct rchan_buf *)page_private(buf->page); |
| relay_consume_bytes(rbuf, buf->private); |
| } |
| |
| static const struct pipe_buf_operations relay_pipe_buf_ops = { |
| .release = relay_pipe_buf_release, |
| .try_steal = generic_pipe_buf_try_steal, |
| .get = generic_pipe_buf_get, |
| }; |
| |
| static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i) |
| { |
| } |
| |
| /* |
| * subbuf_splice_actor - splice up to one subbuf's worth of data |
| */ |
| static ssize_t subbuf_splice_actor(struct file *in, |
| loff_t *ppos, |
| struct pipe_inode_info *pipe, |
| size_t len, |
| unsigned int flags, |
| int *nonpad_ret) |
| { |
| unsigned int pidx, poff, total_len, subbuf_pages, nr_pages; |
| struct rchan_buf *rbuf = in->private_data; |
| unsigned int subbuf_size = rbuf->chan->subbuf_size; |
| uint64_t pos = (uint64_t) *ppos; |
| uint32_t alloc_size = (uint32_t) rbuf->chan->alloc_size; |
| size_t read_start = (size_t) do_div(pos, alloc_size); |
| size_t read_subbuf = read_start / subbuf_size; |
| size_t padding = rbuf->padding[read_subbuf]; |
| size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding; |
| struct page *pages[PIPE_DEF_BUFFERS]; |
| struct partial_page partial[PIPE_DEF_BUFFERS]; |
| struct splice_pipe_desc spd = { |
| .pages = pages, |
| .nr_pages = 0, |
| .nr_pages_max = PIPE_DEF_BUFFERS, |
| .partial = partial, |
| .ops = &relay_pipe_buf_ops, |
| .spd_release = relay_page_release, |
| }; |
| ssize_t ret; |
| |
| if (rbuf->subbufs_produced == rbuf->subbufs_consumed) |
| return 0; |
| if (splice_grow_spd(pipe, &spd)) |
| return -ENOMEM; |
| |
| /* |
| * Adjust read len, if longer than what is available |
| */ |
| if (len > (subbuf_size - read_start % subbuf_size)) |
| len = subbuf_size - read_start % subbuf_size; |
| |
| subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT; |
| pidx = (read_start / PAGE_SIZE) % subbuf_pages; |
| poff = read_start & ~PAGE_MASK; |
| nr_pages = min_t(unsigned int, subbuf_pages, spd.nr_pages_max); |
| |
| for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) { |
| unsigned int this_len, this_end, private; |
| unsigned int cur_pos = read_start + total_len; |
| |
| if (!len) |
| break; |
| |
| this_len = min_t(unsigned long, len, PAGE_SIZE - poff); |
| private = this_len; |
| |
| spd.pages[spd.nr_pages] = rbuf->page_array[pidx]; |
| spd.partial[spd.nr_pages].offset = poff; |
| |
| this_end = cur_pos + this_len; |
| if (this_end >= nonpad_end) { |
| this_len = nonpad_end - cur_pos; |
| private = this_len + padding; |
| } |
| spd.partial[spd.nr_pages].len = this_len; |
| spd.partial[spd.nr_pages].private = private; |
| |
| len -= this_len; |
| total_len += this_len; |
| poff = 0; |
| pidx = (pidx + 1) % subbuf_pages; |
| |
| if (this_end >= nonpad_end) { |
| spd.nr_pages++; |
| break; |
| } |
| } |
| |
| ret = 0; |
| if (!spd.nr_pages) |
| goto out; |
| |
| ret = *nonpad_ret = splice_to_pipe(pipe, &spd); |
| if (ret < 0 || ret < total_len) |
| goto out; |
| |
| if (read_start + ret == nonpad_end) |
| ret += padding; |
| |
| out: |
| splice_shrink_spd(&spd); |
| return ret; |
| } |
| |
| static ssize_t relay_file_splice_read(struct file *in, |
| loff_t *ppos, |
| struct pipe_inode_info *pipe, |
| size_t len, |
| unsigned int flags) |
| { |
| ssize_t spliced; |
| int ret; |
| int nonpad_ret = 0; |
| |
| ret = 0; |
| spliced = 0; |
| |
| while (len && !spliced) { |
| ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret); |
| if (ret < 0) |
| break; |
| else if (!ret) { |
| if (flags & SPLICE_F_NONBLOCK) |
| ret = -EAGAIN; |
| break; |
| } |
| |
| *ppos += ret; |
| if (ret > len) |
| len = 0; |
| else |
| len -= ret; |
| spliced += nonpad_ret; |
| nonpad_ret = 0; |
| } |
| |
| if (spliced) |
| return spliced; |
| |
| return ret; |
| } |
| |
| const struct file_operations relay_file_operations = { |
| .open = relay_file_open, |
| .poll = relay_file_poll, |
| .mmap = relay_file_mmap, |
| .read = relay_file_read, |
| .llseek = no_llseek, |
| .release = relay_file_release, |
| .splice_read = relay_file_splice_read, |
| }; |
| EXPORT_SYMBOL_GPL(relay_file_operations); |