mm: stack based kmap_atomic()
Keep the current interface but ignore the KM_type and use a stack based
approach.
The advantage is that we get rid of crappy code like:
#define __KM_PTE \
(in_nmi() ? KM_NMI_PTE : \
in_irq() ? KM_IRQ_PTE : \
KM_PTE0)
and in general can stop worrying about what context we're in and what kmap
slots might be appropriate for that.
The downside is that FRV kmap_atomic() gets more expensive.
For now we use a CPP trick suggested by Andrew:
#define kmap_atomic(page, args...) __kmap_atomic(page)
to avoid having to touch all kmap_atomic() users in a single patch.
[ not compiled on:
- mn10300: the arch doesn't actually build with highmem to begin with ]
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix up drivers/gpu/drm/i915/intel_overlay.c]
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Miller <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Airlie <airlied@linux.ie>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 283cd47..8a85ec1 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -28,18 +28,6 @@
#include <asm/kmap_types.h>
-#ifdef CONFIG_DEBUG_HIGHMEM
-
-void debug_kmap_atomic(enum km_type type);
-
-#else
-
-static inline void debug_kmap_atomic(enum km_type type)
-{
-}
-
-#endif
-
#ifdef CONFIG_HIGHMEM
#include <asm/highmem.h>
@@ -49,6 +37,27 @@
void kmap_flush_unused(void);
+DECLARE_PER_CPU(int, __kmap_atomic_idx);
+
+static inline int kmap_atomic_idx_push(void)
+{
+ int idx = __get_cpu_var(__kmap_atomic_idx)++;
+#ifdef CONFIG_DEBUG_HIGHMEM
+ WARN_ON_ONCE(in_irq() && !irqs_disabled());
+ BUG_ON(idx > KM_TYPE_NR);
+#endif
+ return idx;
+}
+
+static inline int kmap_atomic_idx_pop(void)
+{
+ int idx = --__get_cpu_var(__kmap_atomic_idx);
+#ifdef CONFIG_DEBUG_HIGHMEM
+ BUG_ON(idx < 0);
+#endif
+ return idx;
+}
+
#else /* CONFIG_HIGHMEM */
static inline unsigned int nr_free_highpages(void) { return 0; }
@@ -66,19 +75,19 @@
{
}
-static inline void *kmap_atomic(struct page *page, enum km_type idx)
+static inline void *__kmap_atomic(struct page *page)
{
pagefault_disable();
return page_address(page);
}
-#define kmap_atomic_prot(page, idx, prot) kmap_atomic(page, idx)
+#define kmap_atomic_prot(page, prot) __kmap_atomic(page)
-static inline void kunmap_atomic_notypecheck(void *addr, enum km_type idx)
+static inline void __kunmap_atomic(void *addr)
{
pagefault_enable();
}
-#define kmap_atomic_pfn(pfn, idx) kmap_atomic(pfn_to_page(pfn), (idx))
+#define kmap_atomic_pfn(pfn) kmap_atomic(pfn_to_page(pfn))
#define kmap_atomic_to_page(ptr) virt_to_page(ptr)
#define kmap_flush_unused() do {} while(0)
@@ -86,12 +95,20 @@
#endif /* CONFIG_HIGHMEM */
-/* Prevent people trying to call kunmap_atomic() as if it were kunmap() */
-/* kunmap_atomic() should get the return value of kmap_atomic, not the page. */
-#define kunmap_atomic(addr, idx) do { \
- BUILD_BUG_ON(__same_type((addr), struct page *)); \
- kunmap_atomic_notypecheck((addr), (idx)); \
- } while (0)
+/*
+ * Make both: kmap_atomic(page, idx) and kmap_atomic(page) work.
+ */
+#define kmap_atomic(page, args...) __kmap_atomic(page)
+
+/*
+ * Prevent people trying to call kunmap_atomic() as if it were kunmap()
+ * kunmap_atomic() should get the return value of kmap_atomic, not the page.
+ */
+#define kunmap_atomic(addr, args...) \
+do { \
+ BUILD_BUG_ON(__same_type((addr), struct page *)); \
+ __kunmap_atomic(addr); \
+} while (0)
/* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */
#ifndef clear_user_highpage