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/mm/highmem.c b/mm/highmem.c
index 7a0aa1b..781e754 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -42,6 +42,10 @@
unsigned long totalhigh_pages __read_mostly;
EXPORT_SYMBOL(totalhigh_pages);
+
+DEFINE_PER_CPU(int, __kmap_atomic_idx);
+EXPORT_PER_CPU_SYMBOL(__kmap_atomic_idx);
+
unsigned int nr_free_highpages (void)
{
pg_data_t *pgdat;
@@ -422,61 +426,3 @@
}
#endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */
-
-#ifdef CONFIG_DEBUG_HIGHMEM
-
-void debug_kmap_atomic(enum km_type type)
-{
- static int warn_count = 10;
-
- if (unlikely(warn_count < 0))
- return;
-
- if (unlikely(in_interrupt())) {
- if (in_nmi()) {
- if (type != KM_NMI && type != KM_NMI_PTE) {
- WARN_ON(1);
- warn_count--;
- }
- } else if (in_irq()) {
- if (type != KM_IRQ0 && type != KM_IRQ1 &&
- type != KM_BIO_SRC_IRQ && type != KM_BIO_DST_IRQ &&
- type != KM_BOUNCE_READ && type != KM_IRQ_PTE) {
- WARN_ON(1);
- warn_count--;
- }
- } else if (!irqs_disabled()) { /* softirq */
- if (type != KM_IRQ0 && type != KM_IRQ1 &&
- type != KM_SOFTIRQ0 && type != KM_SOFTIRQ1 &&
- type != KM_SKB_SUNRPC_DATA &&
- type != KM_SKB_DATA_SOFTIRQ &&
- type != KM_BOUNCE_READ) {
- WARN_ON(1);
- warn_count--;
- }
- }
- }
-
- if (type == KM_IRQ0 || type == KM_IRQ1 || type == KM_BOUNCE_READ ||
- type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ ||
- type == KM_IRQ_PTE || type == KM_NMI ||
- type == KM_NMI_PTE ) {
- if (!irqs_disabled()) {
- WARN_ON(1);
- warn_count--;
- }
- } else if (type == KM_SOFTIRQ0 || type == KM_SOFTIRQ1) {
- if (irq_count() == 0 && !irqs_disabled()) {
- WARN_ON(1);
- warn_count--;
- }
- }
-#ifdef CONFIG_KGDB_KDB
- if (unlikely(type == KM_KDB && atomic_read(&kgdb_active) == -1)) {
- WARN_ON(1);
- warn_count--;
- }
-#endif /* CONFIG_KGDB_KDB */
-}
-
-#endif