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Subject[PATCH v1 04/15] mm: explicitly disable/enable preemption in kmap_atomic_*
Date
The existing code relies on pagefault_disable() implicitly disabling
preemption, so that no schedule will happen between kmap_atomic() and
kunmap_atomic().

Let's make this explicit, to prepare for pagefault_disable() not
touching preemption anymore.

Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
---
arch/arm/mm/highmem.c | 3 +++
arch/frv/mm/highmem.c | 2 ++
arch/metag/mm/highmem.c | 4 +++-
arch/microblaze/mm/highmem.c | 4 +++-
arch/mips/mm/highmem.c | 5 ++++-
arch/mn10300/include/asm/highmem.h | 3 +++
arch/parisc/include/asm/cacheflush.h | 2 ++
arch/powerpc/mm/highmem.c | 4 +++-
arch/sparc/mm/highmem.c | 4 +++-
arch/tile/mm/highmem.c | 3 ++-
arch/x86/mm/highmem_32.c | 3 ++-
arch/x86/mm/iomap_32.c | 2 ++
arch/xtensa/mm/highmem.c | 2 ++
include/linux/highmem.h | 2 ++
include/linux/io-mapping.h | 2 ++
15 files changed, 38 insertions(+), 7 deletions(-)

diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
index b98895d..ee8dfa7 100644
--- a/arch/arm/mm/highmem.c
+++ b/arch/arm/mm/highmem.c
@@ -59,6 +59,7 @@ void *kmap_atomic(struct page *page)
void *kmap;
int type;

+ preempt_disable();
pagefault_disable();
if (!PageHighMem(page))
return page_address(page);
@@ -121,6 +122,7 @@ void __kunmap_atomic(void *kvaddr)
kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
}
pagefault_enable();
+ preempt_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);

@@ -130,6 +132,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
int idx, type;
struct page *page = pfn_to_page(pfn);

+ preempt_disable();
pagefault_disable();
if (!PageHighMem(page))
return page_address(page);
diff --git a/arch/frv/mm/highmem.c b/arch/frv/mm/highmem.c
index bed9a9b..785344b 100644
--- a/arch/frv/mm/highmem.c
+++ b/arch/frv/mm/highmem.c
@@ -42,6 +42,7 @@ void *kmap_atomic(struct page *page)
unsigned long paddr;
int type;

+ preempt_disable();
pagefault_disable();
type = kmap_atomic_idx_push();
paddr = page_to_phys(page);
@@ -85,5 +86,6 @@ void __kunmap_atomic(void *kvaddr)
}
kmap_atomic_idx_pop();
pagefault_enable();
+ preempt_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);
diff --git a/arch/metag/mm/highmem.c b/arch/metag/mm/highmem.c
index d71f621..807f1b1 100644
--- a/arch/metag/mm/highmem.c
+++ b/arch/metag/mm/highmem.c
@@ -43,7 +43,7 @@ void *kmap_atomic(struct page *page)
unsigned long vaddr;
int type;

- /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
+ preempt_disable();
pagefault_disable();
if (!PageHighMem(page))
return page_address(page);
@@ -82,6 +82,7 @@ void __kunmap_atomic(void *kvaddr)
}

pagefault_enable();
+ preempt_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);

@@ -95,6 +96,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
unsigned long vaddr;
int type;

+ preempt_disable();
pagefault_disable();

type = kmap_atomic_idx_push();
diff --git a/arch/microblaze/mm/highmem.c b/arch/microblaze/mm/highmem.c
index 5a92576..2fcc5a5 100644
--- a/arch/microblaze/mm/highmem.c
+++ b/arch/microblaze/mm/highmem.c
@@ -37,7 +37,7 @@ void *kmap_atomic_prot(struct page *page, pgprot_t prot)
unsigned long vaddr;
int idx, type;

- /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
+ preempt_disable();
pagefault_disable();
if (!PageHighMem(page))
return page_address(page);
@@ -63,6 +63,7 @@ void __kunmap_atomic(void *kvaddr)

if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
pagefault_enable();
+ preempt_enable();
return;
}

@@ -84,5 +85,6 @@ void __kunmap_atomic(void *kvaddr)
#endif
kmap_atomic_idx_pop();
pagefault_enable();
+ preempt_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);
diff --git a/arch/mips/mm/highmem.c b/arch/mips/mm/highmem.c
index da815d2..11661cb 100644
--- a/arch/mips/mm/highmem.c
+++ b/arch/mips/mm/highmem.c
@@ -47,7 +47,7 @@ void *kmap_atomic(struct page *page)
unsigned long vaddr;
int idx, type;

- /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
+ preempt_disable();
pagefault_disable();
if (!PageHighMem(page))
return page_address(page);
@@ -72,6 +72,7 @@ void __kunmap_atomic(void *kvaddr)

if (vaddr < FIXADDR_START) { // FIXME
pagefault_enable();
+ preempt_enable();
return;
}

@@ -92,6 +93,7 @@ void __kunmap_atomic(void *kvaddr)
#endif
kmap_atomic_idx_pop();
pagefault_enable();
+ preempt_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);

@@ -104,6 +106,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
unsigned long vaddr;
int idx, type;

+ preempt_disable();
pagefault_disable();

type = kmap_atomic_idx_push();
diff --git a/arch/mn10300/include/asm/highmem.h b/arch/mn10300/include/asm/highmem.h
index 2fbbe4d..1ddea5a 100644
--- a/arch/mn10300/include/asm/highmem.h
+++ b/arch/mn10300/include/asm/highmem.h
@@ -75,6 +75,7 @@ static inline void *kmap_atomic(struct page *page)
unsigned long vaddr;
int idx, type;

+ preempt_disable();
pagefault_disable();
if (page < highmem_start_page)
return page_address(page);
@@ -98,6 +99,7 @@ static inline void __kunmap_atomic(unsigned long vaddr)

if (vaddr < FIXADDR_START) { /* FIXME */
pagefault_enable();
+ preempt_enable();
return;
}

@@ -122,6 +124,7 @@ static inline void __kunmap_atomic(unsigned long vaddr)

kmap_atomic_idx_pop();
pagefault_enable();
+ preempt_enable();
}
#endif /* __KERNEL__ */

diff --git a/arch/parisc/include/asm/cacheflush.h b/arch/parisc/include/asm/cacheflush.h
index de65f66..ec2df4b 100644
--- a/arch/parisc/include/asm/cacheflush.h
+++ b/arch/parisc/include/asm/cacheflush.h
@@ -142,6 +142,7 @@ static inline void kunmap(struct page *page)

static inline void *kmap_atomic(struct page *page)
{
+ preempt_disable();
pagefault_disable();
return page_address(page);
}
@@ -150,6 +151,7 @@ static inline void __kunmap_atomic(void *addr)
{
flush_kernel_dcache_page_addr(addr);
pagefault_enable();
+ preempt_enable();
}

#define kmap_atomic_prot(page, prot) kmap_atomic(page)
diff --git a/arch/powerpc/mm/highmem.c b/arch/powerpc/mm/highmem.c
index e7450bd..e292c8a 100644
--- a/arch/powerpc/mm/highmem.c
+++ b/arch/powerpc/mm/highmem.c
@@ -34,7 +34,7 @@ void *kmap_atomic_prot(struct page *page, pgprot_t prot)
unsigned long vaddr;
int idx, type;

- /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
+ preempt_disable();
pagefault_disable();
if (!PageHighMem(page))
return page_address(page);
@@ -59,6 +59,7 @@ void __kunmap_atomic(void *kvaddr)

if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
pagefault_enable();
+ preempt_enable();
return;
}

@@ -82,5 +83,6 @@ void __kunmap_atomic(void *kvaddr)

kmap_atomic_idx_pop();
pagefault_enable();
+ preempt_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);
diff --git a/arch/sparc/mm/highmem.c b/arch/sparc/mm/highmem.c
index 449f864..a454ec5 100644
--- a/arch/sparc/mm/highmem.c
+++ b/arch/sparc/mm/highmem.c
@@ -53,7 +53,7 @@ void *kmap_atomic(struct page *page)
unsigned long vaddr;
long idx, type;

- /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
+ preempt_disable();
pagefault_disable();
if (!PageHighMem(page))
return page_address(page);
@@ -91,6 +91,7 @@ void __kunmap_atomic(void *kvaddr)

if (vaddr < FIXADDR_START) { // FIXME
pagefault_enable();
+ preempt_enable();
return;
}

@@ -126,5 +127,6 @@ void __kunmap_atomic(void *kvaddr)

kmap_atomic_idx_pop();
pagefault_enable();
+ preempt_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);
diff --git a/arch/tile/mm/highmem.c b/arch/tile/mm/highmem.c
index 6aa2f26..fcd5450 100644
--- a/arch/tile/mm/highmem.c
+++ b/arch/tile/mm/highmem.c
@@ -201,7 +201,7 @@ void *kmap_atomic_prot(struct page *page, pgprot_t prot)
int idx, type;
pte_t *pte;

- /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
+ preempt_disable();
pagefault_disable();

/* Avoid icache flushes by disallowing atomic executable mappings. */
@@ -259,6 +259,7 @@ void __kunmap_atomic(void *kvaddr)
}

pagefault_enable();
+ preempt_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);

diff --git a/arch/x86/mm/highmem_32.c b/arch/x86/mm/highmem_32.c
index 4500142..eecb207a 100644
--- a/arch/x86/mm/highmem_32.c
+++ b/arch/x86/mm/highmem_32.c
@@ -35,7 +35,7 @@ void *kmap_atomic_prot(struct page *page, pgprot_t prot)
unsigned long vaddr;
int idx, type;

- /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
+ preempt_disable();
pagefault_disable();

if (!PageHighMem(page))
@@ -100,6 +100,7 @@ void __kunmap_atomic(void *kvaddr)
#endif

pagefault_enable();
+ preempt_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);

diff --git a/arch/x86/mm/iomap_32.c b/arch/x86/mm/iomap_32.c
index 9ca35fc..2b7ece0 100644
--- a/arch/x86/mm/iomap_32.c
+++ b/arch/x86/mm/iomap_32.c
@@ -59,6 +59,7 @@ void *kmap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
unsigned long vaddr;
int idx, type;

+ preempt_disable();
pagefault_disable();

type = kmap_atomic_idx_push();
@@ -117,5 +118,6 @@ iounmap_atomic(void __iomem *kvaddr)
}

pagefault_enable();
+ preempt_enable();
}
EXPORT_SYMBOL_GPL(iounmap_atomic);
diff --git a/arch/xtensa/mm/highmem.c b/arch/xtensa/mm/highmem.c
index 8cfb71e..184cead 100644
--- a/arch/xtensa/mm/highmem.c
+++ b/arch/xtensa/mm/highmem.c
@@ -42,6 +42,7 @@ void *kmap_atomic(struct page *page)
enum fixed_addresses idx;
unsigned long vaddr;

+ preempt_disable();
pagefault_disable();
if (!PageHighMem(page))
return page_address(page);
@@ -79,6 +80,7 @@ void __kunmap_atomic(void *kvaddr)
}

pagefault_enable();
+ preempt_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 9286a46..6aefcd0 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -65,6 +65,7 @@ static inline void kunmap(struct page *page)

static inline void *kmap_atomic(struct page *page)
{
+ preempt_disable();
pagefault_disable();
return page_address(page);
}
@@ -73,6 +74,7 @@ static inline void *kmap_atomic(struct page *page)
static inline void __kunmap_atomic(void *addr)
{
pagefault_enable();
+ preempt_enable();
}

#define kmap_atomic_pfn(pfn) kmap_atomic(pfn_to_page(pfn))
diff --git a/include/linux/io-mapping.h b/include/linux/io-mapping.h
index 657fab4..c27dde7 100644
--- a/include/linux/io-mapping.h
+++ b/include/linux/io-mapping.h
@@ -141,6 +141,7 @@ static inline void __iomem *
io_mapping_map_atomic_wc(struct io_mapping *mapping,
unsigned long offset)
{
+ preempt_disable();
pagefault_disable();
return ((char __force __iomem *) mapping) + offset;
}
@@ -149,6 +150,7 @@ static inline void
io_mapping_unmap_atomic(void __iomem *vaddr)
{
pagefault_enable();
+ preempt_enable();
}

/* Non-atomic map/unmap */
--
2.1.4


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