GenWQE: Fix multithreading problems
When being used in a multithreaded application there were problems
with memory pages/cachelines accessed by multiple threads/cpus at the
same time, while doing DMA transfers to/from those. To avoid such
situations this fix is creating a copy of the first and the last page
if it is not fully used. The data is copied from user-space into those
pages and results are copied back when the DDCB-request is
successfully finished.
Signed-off-by: Frank Haverkamp <haver@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/misc/genwqe/card_utils.c b/drivers/misc/genwqe/card_utils.c
index 6b1a6ef..d049d27 100644
--- a/drivers/misc/genwqe/card_utils.c
+++ b/drivers/misc/genwqe/card_utils.c
@@ -275,67 +275,107 @@
return roundup(len, PAGE_SIZE);
}
-struct sg_entry *genwqe_alloc_sgl(struct genwqe_dev *cd, int num_pages,
- dma_addr_t *dma_addr, size_t *sgl_size)
+/**
+ * genwqe_alloc_sync_sgl() - Allocate memory for sgl and overlapping pages
+ *
+ * Allocates memory for sgl and overlapping pages. Pages which might
+ * overlap other user-space memory blocks are being cached for DMAs,
+ * such that we do not run into syncronization issues. Data is copied
+ * from user-space into the cached pages.
+ */
+int genwqe_alloc_sync_sgl(struct genwqe_dev *cd, struct genwqe_sgl *sgl,
+ void __user *user_addr, size_t user_size)
{
+ int rc;
struct pci_dev *pci_dev = cd->pci_dev;
- struct sg_entry *sgl;
- *sgl_size = genwqe_sgl_size(num_pages);
- if (get_order(*sgl_size) > MAX_ORDER) {
+ sgl->fpage_offs = offset_in_page((unsigned long)user_addr);
+ sgl->fpage_size = min_t(size_t, PAGE_SIZE-sgl->fpage_offs, user_size);
+ sgl->nr_pages = DIV_ROUND_UP(sgl->fpage_offs + user_size, PAGE_SIZE);
+ sgl->lpage_size = (user_size - sgl->fpage_size) % PAGE_SIZE;
+
+ dev_dbg(&pci_dev->dev, "[%s] uaddr=%p usize=%8ld nr_pages=%ld "
+ "fpage_offs=%lx fpage_size=%ld lpage_size=%ld\n",
+ __func__, user_addr, user_size, sgl->nr_pages,
+ sgl->fpage_offs, sgl->fpage_size, sgl->lpage_size);
+
+ sgl->user_addr = user_addr;
+ sgl->user_size = user_size;
+ sgl->sgl_size = genwqe_sgl_size(sgl->nr_pages);
+
+ if (get_order(sgl->sgl_size) > MAX_ORDER) {
dev_err(&pci_dev->dev,
"[%s] err: too much memory requested!\n", __func__);
- return NULL;
+ return -ENOMEM;
}
- sgl = __genwqe_alloc_consistent(cd, *sgl_size, dma_addr);
- if (sgl == NULL) {
+ sgl->sgl = __genwqe_alloc_consistent(cd, sgl->sgl_size,
+ &sgl->sgl_dma_addr);
+ if (sgl->sgl == NULL) {
dev_err(&pci_dev->dev,
"[%s] err: no memory available!\n", __func__);
- return NULL;
+ return -ENOMEM;
}
- return sgl;
+ /* Only use buffering on incomplete pages */
+ if ((sgl->fpage_size != 0) && (sgl->fpage_size != PAGE_SIZE)) {
+ sgl->fpage = __genwqe_alloc_consistent(cd, PAGE_SIZE,
+ &sgl->fpage_dma_addr);
+ if (sgl->fpage == NULL)
+ goto err_out;
+
+ /* Sync with user memory */
+ if (copy_from_user(sgl->fpage + sgl->fpage_offs,
+ user_addr, sgl->fpage_size)) {
+ rc = -EFAULT;
+ goto err_out;
+ }
+ }
+ if (sgl->lpage_size != 0) {
+ sgl->lpage = __genwqe_alloc_consistent(cd, PAGE_SIZE,
+ &sgl->lpage_dma_addr);
+ if (sgl->lpage == NULL)
+ goto err_out1;
+
+ /* Sync with user memory */
+ if (copy_from_user(sgl->lpage, user_addr + user_size -
+ sgl->lpage_size, sgl->lpage_size)) {
+ rc = -EFAULT;
+ goto err_out1;
+ }
+ }
+ return 0;
+
+ err_out1:
+ __genwqe_free_consistent(cd, PAGE_SIZE, sgl->fpage,
+ sgl->fpage_dma_addr);
+ err_out:
+ __genwqe_free_consistent(cd, sgl->sgl_size, sgl->sgl,
+ sgl->sgl_dma_addr);
+ return -ENOMEM;
}
-int genwqe_setup_sgl(struct genwqe_dev *cd,
- unsigned long offs,
- unsigned long size,
- struct sg_entry *sgl,
- dma_addr_t dma_addr, size_t sgl_size,
- dma_addr_t *dma_list, int page_offs, int num_pages)
+int genwqe_setup_sgl(struct genwqe_dev *cd, struct genwqe_sgl *sgl,
+ dma_addr_t *dma_list)
{
int i = 0, j = 0, p;
unsigned long dma_offs, map_offs;
- struct pci_dev *pci_dev = cd->pci_dev;
dma_addr_t prev_daddr = 0;
struct sg_entry *s, *last_s = NULL;
-
- /* sanity checks */
- if (offs > PAGE_SIZE) {
- dev_err(&pci_dev->dev,
- "[%s] too large start offs %08lx\n", __func__, offs);
- return -EFAULT;
- }
- if (sgl_size < genwqe_sgl_size(num_pages)) {
- dev_err(&pci_dev->dev,
- "[%s] sgl_size too small %08lx for %d pages\n",
- __func__, sgl_size, num_pages);
- return -EFAULT;
- }
+ size_t size = sgl->user_size;
dma_offs = 128; /* next block if needed/dma_offset */
- map_offs = offs; /* offset in first page */
+ map_offs = sgl->fpage_offs; /* offset in first page */
- s = &sgl[0]; /* first set of 8 entries */
+ s = &sgl->sgl[0]; /* first set of 8 entries */
p = 0; /* page */
- while (p < num_pages) {
+ while (p < sgl->nr_pages) {
dma_addr_t daddr;
unsigned int size_to_map;
/* always write the chaining entry, cleanup is done later */
j = 0;
- s[j].target_addr = cpu_to_be64(dma_addr + dma_offs);
+ s[j].target_addr = cpu_to_be64(sgl->sgl_dma_addr + dma_offs);
s[j].len = cpu_to_be32(128);
s[j].flags = cpu_to_be32(SG_CHAINED);
j++;
@@ -343,7 +383,17 @@
while (j < 8) {
/* DMA mapping for requested page, offs, size */
size_to_map = min(size, PAGE_SIZE - map_offs);
- daddr = dma_list[page_offs + p] + map_offs;
+
+ if ((p == 0) && (sgl->fpage != NULL)) {
+ daddr = sgl->fpage_dma_addr + map_offs;
+
+ } else if ((p == sgl->nr_pages - 1) &&
+ (sgl->lpage != NULL)) {
+ daddr = sgl->lpage_dma_addr;
+ } else {
+ daddr = dma_list[p] + map_offs;
+ }
+
size -= size_to_map;
map_offs = 0;
@@ -358,7 +408,7 @@
size_to_map);
p++; /* process next page */
- if (p == num_pages)
+ if (p == sgl->nr_pages)
goto fixup; /* nothing to do */
prev_daddr = daddr + size_to_map;
@@ -374,7 +424,7 @@
j++;
p++; /* process next page */
- if (p == num_pages)
+ if (p == sgl->nr_pages)
goto fixup; /* nothing to do */
}
dma_offs += 128;
@@ -395,10 +445,50 @@
return 0;
}
-void genwqe_free_sgl(struct genwqe_dev *cd, struct sg_entry *sg_list,
- dma_addr_t dma_addr, size_t size)
+/**
+ * genwqe_free_sync_sgl() - Free memory for sgl and overlapping pages
+ *
+ * After the DMA transfer has been completed we free the memory for
+ * the sgl and the cached pages. Data is being transfered from cached
+ * pages into user-space buffers.
+ */
+int genwqe_free_sync_sgl(struct genwqe_dev *cd, struct genwqe_sgl *sgl)
{
- __genwqe_free_consistent(cd, size, sg_list, dma_addr);
+ int rc;
+ struct pci_dev *pci_dev = cd->pci_dev;
+
+ if (sgl->fpage) {
+ if (copy_to_user(sgl->user_addr, sgl->fpage + sgl->fpage_offs,
+ sgl->fpage_size)) {
+ dev_err(&pci_dev->dev, "[%s] err: copying fpage!\n",
+ __func__);
+ rc = -EFAULT;
+ }
+ __genwqe_free_consistent(cd, PAGE_SIZE, sgl->fpage,
+ sgl->fpage_dma_addr);
+ sgl->fpage = NULL;
+ sgl->fpage_dma_addr = 0;
+ }
+ if (sgl->lpage) {
+ if (copy_to_user(sgl->user_addr + sgl->user_size -
+ sgl->lpage_size, sgl->lpage,
+ sgl->lpage_size)) {
+ dev_err(&pci_dev->dev, "[%s] err: copying lpage!\n",
+ __func__);
+ rc = -EFAULT;
+ }
+ __genwqe_free_consistent(cd, PAGE_SIZE, sgl->lpage,
+ sgl->lpage_dma_addr);
+ sgl->lpage = NULL;
+ sgl->lpage_dma_addr = 0;
+ }
+ __genwqe_free_consistent(cd, sgl->sgl_size, sgl->sgl,
+ sgl->sgl_dma_addr);
+
+ sgl->sgl = NULL;
+ sgl->sgl_dma_addr = 0x0;
+ sgl->sgl_size = 0;
+ return rc;
}
/**