intel_th: msu: Split sgt array and pointer in multiwindow mode

To allow the use of externally allocated SG tables further down the line,
change the code to reference the table via a pointer and make it point to
the locally allocated table by default.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20190627125152.54905-4-alexander.shishkin@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwtracing/intel_th/msu.c b/drivers/hwtracing/intel_th/msu.c
index c9c29f5..aedfd86 100644 (file)
--- a/drivers/hwtracing/intel_th/msu.c
+++ b/drivers/hwtracing/intel_th/msu.c
@@ -34,6 +34,7 @@
  * @pgoff:     page offset into the buffer that this window starts at
  * @nr_blocks: number of blocks (pages) in this window
  * @nr_segs:   number of segments in this window (<= @nr_blocks)
+ * @_sgt:      array of block descriptors
  * @sgt:       array of block descriptors
  */
 struct msc_window {
@@ -42,7 +43,8 @@ struct msc_window {
        unsigned int            nr_blocks;
        unsigned int            nr_segs;
        struct msc              *msc;
-       struct sg_table         sgt;
+       struct sg_table         _sgt;
+       struct sg_table         *sgt;
 };
 
 /**
@@ -140,19 +142,19 @@ static inline bool msc_block_is_empty(struct msc_block_desc *bdesc)
 static inline struct msc_block_desc *
 msc_win_block(struct msc_window *win, unsigned int block)
 {
-       return sg_virt(&win->sgt.sgl[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;
+       return win->sgt->sgl[block].length;
 }
 
 static inline dma_addr_t
 msc_win_baddr(struct msc_window *win, unsigned int block)
 {
-       return sg_dma_address(&win->sgt.sgl[block]);
+       return sg_dma_address(&win->sgt->sgl[block]);
 }
 
 static inline unsigned long
@@ -748,11 +750,11 @@ static int __msc_buffer_win_alloc(struct msc_window *win,
        void *block;
        int i, ret;
 
-       ret = sg_alloc_table(&win->sgt, nr_segs, GFP_KERNEL);
+       ret = sg_alloc_table(win->sgt, nr_segs, GFP_KERNEL);
        if (ret)
                return -ENOMEM;
 
-       for_each_sg(win->sgt.sgl, sg_ptr, nr_segs, i) {
+       for_each_sg(win->sgt->sgl, sg_ptr, nr_segs, i) {
                block = dma_alloc_coherent(msc_dev(win->msc)->parent->parent,
                                          PAGE_SIZE, &sg_dma_address(sg_ptr),
                                          GFP_KERNEL);
@@ -770,7 +772,7 @@ err_nomem:
                                  msc_win_block(win, i),
                                  msc_win_baddr(win, i));
 
-       sg_free_table(&win->sgt);
+       sg_free_table(win->sgt);
 
        return -ENOMEM;
 }
@@ -829,6 +831,7 @@ static int msc_buffer_win_alloc(struct msc *msc, unsigned int nr_blocks)
                return -ENOMEM;
 
        win->msc = msc;
+       win->sgt = &win->_sgt;
 
        if (!list_empty(&msc->win_list)) {
                struct msc_window *prev = list_last_entry(&msc->win_list,
@@ -869,13 +872,13 @@ static void __msc_buffer_win_free(struct msc *msc, struct msc_window *win)
        int i;
 
        for (i = 0; i < win->nr_segs; i++) {
-               struct page *page = sg_page(&win->sgt.sgl[i]);
+               struct page *page = sg_page(&win->sgt->sgl[i]);
 
                page->mapping = NULL;
                dma_free_coherent(msc_dev(win->msc)->parent->parent, PAGE_SIZE,
                                  msc_win_block(win, i), msc_win_baddr(win, i));
        }
-       sg_free_table(&win->sgt);
+       sg_free_table(win->sgt);
 }
 
 /**
@@ -1124,7 +1127,7 @@ found:
        pgoff -= win->pgoff;
 
        for (blk = 0; blk < win->nr_segs; blk++) {
-               struct page *page = sg_page(&win->sgt.sgl[blk]);
+               struct page *page = sg_page(&win->sgt->sgl[blk]);
                size_t pgsz = PFN_DOWN(msc_win_actual_bsz(win, blk));
 
                if (pgoff < pgsz)