From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
This is an unusual way to use the xarray tags. If any other users
come up, we can add an xas_get_tags() / xas_set_tags() API, but until
then I don't want to encourage this kind of abuse.
Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
---
lib/dma-debug.c | 105 +++++++++++++++++++++++++-------------------------------
1 file changed, 46 insertions(+), 59 deletions(-)
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index fb4af570ce04..965b3837d060 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -22,7 +22,6 @@
#include <linux/dma-mapping.h>
#include <linux/sched/task.h>
#include <linux/stacktrace.h>
-#include <linux/radix-tree.h>
#include <linux/dma-debug.h>
#include <linux/spinlock.h>
#include <linux/vmalloc.h>
@@ -30,6 +29,7 @@
#include <linux/uaccess.h>
#include <linux/export.h>
#include <linux/device.h>
+#include <linux/xarray.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/ctype.h>
@@ -465,9 +465,8 @@ EXPORT_SYMBOL(debug_dma_dump_mappings);
* At any time debug_dma_assert_idle() can be called to trigger a
* warning if any cachelines in the given page are in the active set.
*/
-static RADIX_TREE(dma_active_cacheline, GFP_NOWAIT);
-static DEFINE_SPINLOCK(radix_lock);
-#define ACTIVE_CACHELINE_MAX_OVERLAP ((1 << RADIX_TREE_MAX_TAGS) - 1)
+static DEFINE_XARRAY_FLAGS(dma_active_cacheline, XA_FLAGS_LOCK_IRQ);
+#define ACTIVE_CACHELINE_MAX_OVERLAP ((1 << XA_MAX_TAGS) - 1)
#define CACHELINE_PER_PAGE_SHIFT (PAGE_SHIFT - L1_CACHE_SHIFT)
#define CACHELINES_PER_PAGE (1 << CACHELINE_PER_PAGE_SHIFT)
@@ -477,37 +476,40 @@ static phys_addr_t to_cacheline_number(struct dma_debug_entry *entry)
(entry->offset >> L1_CACHE_SHIFT);
}
-static int active_cacheline_read_overlap(phys_addr_t cln)
+static unsigned int active_cacheline_read_overlap(struct xa_state *xas)
{
- int overlap = 0, i;
+ unsigned int tags = 0;
+ xa_tag_t tag;
- for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--)
- if (radix_tree_tag_get(&dma_active_cacheline, cln, i))
- overlap |= 1 << i;
- return overlap;
+ for (tag = 0; tag < XA_MAX_TAGS; tag++)
+ if (xas_get_tag(xas, tag))
+ tags |= 1U << tag;
+
+ return tags;
}
-static int active_cacheline_set_overlap(phys_addr_t cln, int overlap)
+static int active_cacheline_set_overlap(struct xa_state *xas, int overlap)
{
- int i;
+ xa_tag_t tag;
if (overlap > ACTIVE_CACHELINE_MAX_OVERLAP || overlap < 0)
return overlap;
- for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--)
- if (overlap & 1 << i)
- radix_tree_tag_set(&dma_active_cacheline, cln, i);
+ for (tag = 0; tag < XA_MAX_TAGS; tag++) {
+ if (overlap & (1U << tag))
+ xas_set_tag(xas, tag);
else
- radix_tree_tag_clear(&dma_active_cacheline, cln, i);
+ xas_clear_tag(xas, tag);
+ }
return overlap;
}
-static void active_cacheline_inc_overlap(phys_addr_t cln)
+static void active_cacheline_inc_overlap(struct xa_state *xas)
{
- int overlap = active_cacheline_read_overlap(cln);
+ int overlap = active_cacheline_read_overlap(xas);
- overlap = active_cacheline_set_overlap(cln, ++overlap);
+ overlap = active_cacheline_set_overlap(xas, ++overlap);
/* If we overflowed the overlap counter then we're potentially
* leaking dma-mappings. Otherwise, if maps and unmaps are
@@ -517,21 +519,22 @@ static void active_cacheline_inc_overlap(phys_addr_t cln)
*/
WARN_ONCE(overlap > ACTIVE_CACHELINE_MAX_OVERLAP,
"DMA-API: exceeded %d overlapping mappings of cacheline %pa\n",
- ACTIVE_CACHELINE_MAX_OVERLAP, &cln);
+ ACTIVE_CACHELINE_MAX_OVERLAP, &xas->xa_index);
}
-static int active_cacheline_dec_overlap(phys_addr_t cln)
+static int active_cacheline_dec_overlap(struct xa_state *xas)
{
- int overlap = active_cacheline_read_overlap(cln);
+ int overlap = active_cacheline_read_overlap(xas);
- return active_cacheline_set_overlap(cln, --overlap);
+ return active_cacheline_set_overlap(xas, --overlap);
}
static int active_cacheline_insert(struct dma_debug_entry *entry)
{
phys_addr_t cln = to_cacheline_number(entry);
+ XA_STATE(xas, &dma_active_cacheline, cln);
unsigned long flags;
- int rc;
+ struct dma_debug_entry *exists;
/* If the device is not writing memory then we don't have any
* concerns about the cpu consuming stale data. This mitigates
@@ -540,32 +543,32 @@ static int active_cacheline_insert(struct dma_debug_entry *entry)
if (entry->direction == DMA_TO_DEVICE)
return 0;
- spin_lock_irqsave(&radix_lock, flags);
- rc = radix_tree_insert(&dma_active_cacheline, cln, entry);
- if (rc == -EEXIST)
- active_cacheline_inc_overlap(cln);
- spin_unlock_irqrestore(&radix_lock, flags);
+ xas_lock_irqsave(&xas, flags);
+ exists = xas_create(&xas);
+ if (exists)
+ active_cacheline_inc_overlap(&xas);
+ else
+ xas_store(&xas, entry);
+ xas_unlock_irqrestore(&xas, flags);
- return rc;
+ return xas_error(&xas);
}
static void active_cacheline_remove(struct dma_debug_entry *entry)
{
phys_addr_t cln = to_cacheline_number(entry);
+ XA_STATE(xas, &dma_active_cacheline, cln);
unsigned long flags;
/* ...mirror the insert case */
if (entry->direction == DMA_TO_DEVICE)
return;
- spin_lock_irqsave(&radix_lock, flags);
- /* since we are counting overlaps the final put of the
- * cacheline will occur when the overlap count is 0.
- * active_cacheline_dec_overlap() returns -1 in that case
- */
- if (active_cacheline_dec_overlap(cln) < 0)
- radix_tree_delete(&dma_active_cacheline, cln);
- spin_unlock_irqrestore(&radix_lock, flags);
+ xas_lock_irqsave(&xas, flags);
+ xas_load(&xas);
+ if (active_cacheline_dec_overlap(&xas) < 0)
+ xas_store(&xas, NULL);
+ xas_unlock_irqrestore(&xas, flags);
}
/**
@@ -578,12 +581,8 @@ static void active_cacheline_remove(struct dma_debug_entry *entry)
*/
void debug_dma_assert_idle(struct page *page)
{
- static struct dma_debug_entry *ents[CACHELINES_PER_PAGE];
- struct dma_debug_entry *entry = NULL;
- void **results = (void **) &ents;
- unsigned int nents, i;
- unsigned long flags;
- phys_addr_t cln;
+ struct dma_debug_entry *entry;
+ unsigned long cln;
if (dma_debug_disabled())
return;
@@ -591,21 +590,9 @@ void debug_dma_assert_idle(struct page *page)
if (!page)
return;
- cln = (phys_addr_t) page_to_pfn(page) << CACHELINE_PER_PAGE_SHIFT;
- spin_lock_irqsave(&radix_lock, flags);
- nents = radix_tree_gang_lookup(&dma_active_cacheline, results, cln,
- CACHELINES_PER_PAGE);
- for (i = 0; i < nents; i++) {
- phys_addr_t ent_cln = to_cacheline_number(ents[i]);
-
- if (ent_cln == cln) {
- entry = ents[i];
- break;
- } else if (ent_cln >= cln + CACHELINES_PER_PAGE)
- break;
- }
- spin_unlock_irqrestore(&radix_lock, flags);
-
+ cln = page_to_pfn(page) << CACHELINE_PER_PAGE_SHIFT;
+ entry = xa_find(&dma_active_cacheline, &cln,
+ cln + CACHELINES_PER_PAGE - 1, XA_PRESENT);
if (!entry)
return;
--
2.15.1
--
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