From 772a7a724f69d258025fedd87dde1aafe4171aef Mon Sep 17 00:00:00 2001 From: Andrzej Pietrasiewicz Date: Wed, 14 Nov 2018 10:47:48 +0100 Subject: usb: gadget: f_fs: Allow scatter-gather buffers Some protocols implemented in userspace with FunctionFS might require large buffers, e.g. 64kB or more. Currently the said memory is allocated with kmalloc, which might fail should system memory be highly fragmented. On the other hand, some UDC hardware allows scatter-gather operation and this patch takes advantage of this capability: if the requested buffer is larger than PAGE_SIZE and the UDC allows scatter-gather operation, then the buffer is allocated with vmalloc and a scatterlist describing it is created and passed to usb request. Signed-off-by: Andrzej Pietrasiewicz Signed-off-by: Felipe Balbi --- drivers/usb/gadget/function/f_fs.c | 93 +++++++++++++++++++++++++++++++++++--- 1 file changed, 86 insertions(+), 7 deletions(-) diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 65b72e5c4605..1e5430438703 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -18,9 +18,12 @@ #include #include #include +#include #include +#include #include #include +#include #include #include @@ -219,6 +222,8 @@ struct ffs_io_data { struct usb_ep *ep; struct usb_request *req; + struct sg_table sgt; + bool use_sg; struct ffs_data *ffs; }; @@ -750,6 +755,65 @@ static ssize_t ffs_copy_to_iter(void *data, int data_len, struct iov_iter *iter) return ret; } +/* + * allocate a virtually contiguous buffer and create a scatterlist describing it + * @sg_table - pointer to a place to be filled with sg_table contents + * @size - required buffer size + */ +static void *ffs_build_sg_list(struct sg_table *sgt, size_t sz) +{ + struct page **pages; + void *vaddr, *ptr; + unsigned int n_pages; + int i; + + vaddr = vmalloc(sz); + if (!vaddr) + return NULL; + + n_pages = PAGE_ALIGN(sz) >> PAGE_SHIFT; + pages = kvmalloc_array(n_pages, sizeof(struct page *), GFP_KERNEL); + if (!pages) { + vfree(vaddr); + + return NULL; + } + for (i = 0, ptr = vaddr; i < n_pages; ++i, ptr += PAGE_SIZE) + pages[i] = vmalloc_to_page(ptr); + + if (sg_alloc_table_from_pages(sgt, pages, n_pages, 0, sz, GFP_KERNEL)) { + kvfree(pages); + vfree(vaddr); + + return NULL; + } + kvfree(pages); + + return vaddr; +} + +static inline void *ffs_alloc_buffer(struct ffs_io_data *io_data, + size_t data_len) +{ + if (io_data->use_sg) + return ffs_build_sg_list(&io_data->sgt, data_len); + + return kmalloc(data_len, GFP_KERNEL); +} + +static inline void ffs_free_buffer(struct ffs_io_data *io_data) +{ + if (!io_data->buf) + return; + + if (io_data->use_sg) { + sg_free_table(&io_data->sgt); + vfree(io_data->buf); + } else { + kfree(io_data->buf); + } +} + static void ffs_user_copy_worker(struct work_struct *work) { struct ffs_io_data *io_data = container_of(work, struct ffs_io_data, @@ -777,7 +841,7 @@ static void ffs_user_copy_worker(struct work_struct *work) if (io_data->read) kfree(io_data->to_free); - kfree(io_data->buf); + ffs_free_buffer(io_data); kfree(io_data); } @@ -933,6 +997,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data) * earlier */ gadget = epfile->ffs->gadget; + io_data->use_sg = gadget->sg_supported && data_len > PAGE_SIZE; spin_lock_irq(&epfile->ffs->eps_lock); /* In the meantime, endpoint got disabled or changed. */ @@ -949,7 +1014,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data) data_len = usb_ep_align_maybe(gadget, ep->ep, data_len); spin_unlock_irq(&epfile->ffs->eps_lock); - data = kmalloc(data_len, GFP_KERNEL); + data = ffs_alloc_buffer(io_data, data_len); if (unlikely(!data)) { ret = -ENOMEM; goto error_mutex; @@ -989,8 +1054,16 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data) bool interrupted = false; req = ep->req; - req->buf = data; - req->length = data_len; + if (io_data->use_sg) { + req->buf = NULL; + req->sg = io_data->sgt.sgl; + req->num_sgs = io_data->sgt.nents; + } else { + req->buf = data; + } + req->length = data_len; + + io_data->buf = data; req->context = &done; req->complete = ffs_epfile_io_complete; @@ -1023,8 +1096,14 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data) } else if (!(req = usb_ep_alloc_request(ep->ep, GFP_ATOMIC))) { ret = -ENOMEM; } else { - req->buf = data; - req->length = data_len; + if (io_data->use_sg) { + req->buf = NULL; + req->sg = io_data->sgt.sgl; + req->num_sgs = io_data->sgt.nents; + } else { + req->buf = data; + } + req->length = data_len; io_data->buf = data; io_data->ep = ep->ep; @@ -1053,7 +1132,7 @@ error_lock: error_mutex: mutex_unlock(&epfile->mutex); error: - kfree(data); + ffs_free_buffer(io_data); return ret; } -- cgit v1.2.3