Now that the MSU is using scatterlist, we can support multipage blocks. At the moment, the code assumes that all blocks are page-sized, but in larger buffers it may make sense to chunk together larger blocks of memory. One place where one-to-many relationship needs to be handled is the MSU buffer's mmap path.
Get rid of the implicit assumption that all blocks are page-sized. Signed-off-by: Alexander Shishkin <[email protected]> --- drivers/hwtracing/intel_th/msu.c | 48 ++++++++++++++++++++++---------- 1 file changed, 34 insertions(+), 14 deletions(-) diff --git a/drivers/hwtracing/intel_th/msu.c b/drivers/hwtracing/intel_th/msu.c index 0e7fbef8dee0..a4f7a5b21d48 100644 --- a/drivers/hwtracing/intel_th/msu.c +++ b/drivers/hwtracing/intel_th/msu.c @@ -32,13 +32,15 @@ * struct msc_window - multiblock mode window descriptor * @entry: window list linkage (msc::win_list) * @pgoff: page offset into the buffer that this window starts at - * @nr_blocks: number of blocks (pages) in this window + * @nr_blocks: number of blocks in this window (<= @nr_pages) + * @nr_pages: number of pages in this window * @sgt: array of block descriptors */ struct msc_window { struct list_head entry; unsigned long pgoff; unsigned int nr_blocks; + unsigned int nr_pages; struct msc *msc; struct sg_table sgt; }; @@ -139,6 +141,12 @@ msc_win_block(struct msc_window *win, unsigned int block) return sg_virt(&win->sgt.sgl[block]); } +static inline size_t +msc_win_actual_bsz(struct msc_window *win, unsigned int block) +{ + return win->sgt.sgl[block].length; +} + static inline dma_addr_t msc_win_baddr(struct msc_window *win, unsigned int block) { @@ -779,26 +787,26 @@ static int __msc_buffer_win_alloc(struct msc_window *win, /** * msc_buffer_win_alloc() - alloc a window for a multiblock mode * @msc: MSC device - * @nr_blocks: number of pages in this window + * @nr_pages: number of pages in this window * * This modifies msc::win_list and msc::base, which requires msc::buf_mutex * to serialize, so the caller is expected to hold it. * * Return: 0 on success, -errno otherwise. */ -static int msc_buffer_win_alloc(struct msc *msc, unsigned int nr_blocks) +static int msc_buffer_win_alloc(struct msc *msc, unsigned int nr_pages) { struct msc_window *win; int ret = -ENOMEM, i; - if (!nr_blocks) + if (!nr_pages) return 0; /* * This limitation hold as long as we need random access to the * block. When that changes, this can go away. */ - if (nr_blocks > SG_MAX_SINGLE_ALLOC) + if (nr_pages > SG_MAX_SINGLE_ALLOC) return -EINVAL; win = kzalloc(sizeof(*win), GFP_KERNEL); @@ -812,11 +820,10 @@ static int msc_buffer_win_alloc(struct msc *msc, unsigned int nr_blocks) struct msc_window, entry); - /* This works as long as blocks are page-sized */ - win->pgoff = prev->pgoff + prev->nr_blocks; + win->pgoff = prev->pgoff + prev->nr_pages; } - ret = __msc_buffer_win_alloc(win, nr_blocks); + ret = __msc_buffer_win_alloc(win, nr_pages); if (ret < 0) goto err_nomem; @@ -827,6 +834,7 @@ static int msc_buffer_win_alloc(struct msc *msc, unsigned int nr_blocks) #endif win->nr_blocks = ret; + win->nr_pages = nr_pages; if (list_empty(&msc->win_list)) { msc->base = msc_win_block(win, 0); @@ -834,7 +842,7 @@ static int msc_buffer_win_alloc(struct msc *msc, unsigned int nr_blocks) } list_add_tail(&win->entry, &msc->win_list); - msc->nr_pages += nr_blocks; + msc->nr_pages += nr_pages; return 0; @@ -870,7 +878,7 @@ static void msc_buffer_win_free(struct msc *msc, struct msc_window *win) { int i; - msc->nr_pages -= win->nr_blocks; + msc->nr_pages -= win->nr_pages; list_del(&win->entry); if (list_empty(&msc->win_list)) { @@ -936,7 +944,7 @@ static void msc_buffer_relink(struct msc *msc) } bdesc->sw_tag = sw_tag; - bdesc->block_sz = PAGE_SIZE / 64; + bdesc->block_sz = msc_win_actual_bsz(win, blk) / 64; } } @@ -1095,19 +1103,31 @@ static int msc_buffer_free_unless_used(struct msc *msc) static struct page *msc_buffer_get_page(struct msc *msc, unsigned long pgoff) { struct msc_window *win; + unsigned int blk; if (msc->mode == MSC_MODE_SINGLE) return msc_buffer_contig_get_page(msc, pgoff); list_for_each_entry(win, &msc->win_list, entry) - if (pgoff >= win->pgoff && pgoff < win->pgoff + win->nr_blocks) + if (pgoff >= win->pgoff && pgoff < win->pgoff + win->nr_pages) goto found; return NULL; found: pgoff -= win->pgoff; - return sg_page(&win->sgt.sgl[pgoff]); + + for (blk = 0; blk < win->nr_blocks; blk++) { + struct page *page = sg_page(&win->sgt.sgl[blk]); + size_t pgsz = win->sgt.sgl[blk].length >> PAGE_SHIFT; + + if (pgoff < pgsz) + return page + pgoff; + + pgoff -= pgsz; + } + + return NULL; } /** @@ -1481,7 +1501,7 @@ nr_pages_show(struct device *dev, struct device_attribute *attr, char *buf) else if (msc->mode == MSC_MODE_MULTI) { list_for_each_entry(win, &msc->win_list, entry) { count += scnprintf(buf + count, PAGE_SIZE - count, - "%d%c", win->nr_blocks, + "%d%c", win->nr_pages, msc_is_last_win(win) ? '\n' : ','); } } else { -- 2.20.1
