diff mbox series

[4/5] arch/kmap_atomic: Consolidate duplicate code

Message ID 20200426055406.134198-5-ira.weiny@intel.com
State New
Headers show
Series Remove duplicated kmap code | expand

Commit Message

Ira Weiny April 26, 2020, 5:54 a.m. UTC 
From: Ira Weiny <ira.weiny@intel.com>

Every arch has the same check for a not HIGHMEM page.  Define
kmap_atomic_fast() to quickly return already mapped pages and reduce the
code duplication by lifting this check to the core.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
 arch/arc/mm/highmem.c        | 7 +++----
 arch/arm/mm/highmem.c        | 8 +++-----
 arch/csky/mm/highmem.c       | 7 +++----
 arch/microblaze/mm/highmem.c | 8 +++-----
 arch/mips/mm/highmem.c       | 7 +++----
 arch/nds32/mm/highmem.c      | 7 +++----
 arch/powerpc/mm/highmem.c    | 7 +++----
 arch/sparc/mm/highmem.c      | 7 +++----
 arch/x86/mm/highmem_32.c     | 8 +++-----
 arch/xtensa/mm/highmem.c     | 7 +++----
 include/linux/highmem.h      | 9 +++++++++
 11 files changed, 39 insertions(+), 43 deletions(-)

Comments

Christoph Hellwig April 26, 2020, 7:26 a.m. UTC | #1 
> diff --git a/arch/arc/mm/highmem.c b/arch/arc/mm/highmem.c
> index 4db13a6b9f3b..1cae4b911a33 100644
> --- a/arch/arc/mm/highmem.c
> +++ b/arch/arc/mm/highmem.c
> @@ -53,11 +53,10 @@ void *kmap_atomic(struct page *page)
>  {
>  	int idx, cpu_idx;
>  	unsigned long vaddr;
> +	void *addr = kmap_atomic_fast(page);
>  
> -	preempt_disable();
> -	pagefault_disable();
> -	if (!PageHighMem(page))
> -		return page_address(page);
> +	if (addr)
> +		return addr;

Wouldn't it make sense to just move kmap_atomic itelf to common code,
and call out to a kmap_atomic_high for the highmem case, following the
scheme in kmap?  Same for the unmap side.  That might require to support
kmap_atomic_prot everywhere first, which sounds like a really good
idea anyway, and would avoid the need for strange workaround in drm.
Ira Weiny April 27, 2020, 1:16 a.m. UTC | #2 
On Sun, Apr 26, 2020 at 12:26:42AM -0700, Christoph Hellwig wrote:
> > diff --git a/arch/arc/mm/highmem.c b/arch/arc/mm/highmem.c
> > index 4db13a6b9f3b..1cae4b911a33 100644
> > --- a/arch/arc/mm/highmem.c
> > +++ b/arch/arc/mm/highmem.c
> > @@ -53,11 +53,10 @@ void *kmap_atomic(struct page *page)
> >  {
> >  	int idx, cpu_idx;
> >  	unsigned long vaddr;
> > +	void *addr = kmap_atomic_fast(page);
> >  
> > -	preempt_disable();
> > -	pagefault_disable();
> > -	if (!PageHighMem(page))
> > -		return page_address(page);
> > +	if (addr)
> > +		return addr;
> 
> Wouldn't it make sense to just move kmap_atomic itelf to common code,
> and call out to a kmap_atomic_high for the highmem case, following the
> scheme in kmap?
>

Sure I do like that symmetry between the calls.

>
> Same for the unmap side.

FWIW that would simply be renaming  __kunmap_atomic() to kunmap_atomic_high()

>
> That might require to support
> kmap_atomic_prot everywhere first, which sounds like a really good
> idea anyway, and would avoid the need for strange workaround in drm.

Having a kmap_atomic_prot() seems like a good idea.  But I'm not exactly sure
why CONFIG_x86 is being called out specifically in the DRM code?

Ira
Christoph Hellwig April 27, 2020, 6:25 a.m. UTC | #3 
On Sun, Apr 26, 2020 at 06:16:30PM -0700, Ira Weiny wrote:
> > That might require to support
> > kmap_atomic_prot everywhere first, which sounds like a really good
> > idea anyway, and would avoid the need for strange workaround in drm.
> 
> Having a kmap_atomic_prot() seems like a good idea.  But I'm not exactly sure
> why CONFIG_x86 is being called out specifically in the DRM code?

Probably because it only existed on x86 back then.  And drm has a
tendency of working around core problems with hacks instead of doing
the fairly easy fixups.
diff mbox series

Patch

diff --git a/arch/arc/mm/highmem.c b/arch/arc/mm/highmem.c
index 4db13a6b9f3b..1cae4b911a33 100644
--- a/arch/arc/mm/highmem.c
+++ b/arch/arc/mm/highmem.c
@@ -53,11 +53,10 @@  void *kmap_atomic(struct page *page)
 {
 	int idx, cpu_idx;
 	unsigned long vaddr;
+	void *addr = kmap_atomic_fast(page);
 
-	preempt_disable();
-	pagefault_disable();
-	if (!PageHighMem(page))
-		return page_address(page);
+	if (addr)
+		return addr;
 
 	cpu_idx = kmap_atomic_idx_push();
 	idx = cpu_idx + KM_TYPE_NR * smp_processor_id();
diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
index c700b32350ee..4a629f616a6a 100644
--- a/arch/arm/mm/highmem.c
+++ b/arch/arm/mm/highmem.c
@@ -35,13 +35,11 @@  void *kmap_atomic(struct page *page)
 {
 	unsigned int idx;
 	unsigned long vaddr;
-	void *kmap;
+	void *kmap = kmap_atomic_fast(page);
 	int type;
 
-	preempt_disable();
-	pagefault_disable();
-	if (!PageHighMem(page))
-		return page_address(page);
+	if (kmap)
+		return kmap;
 
 #ifdef CONFIG_DEBUG_HIGHMEM
 	/*
diff --git a/arch/csky/mm/highmem.c b/arch/csky/mm/highmem.c
index 69b1931986ae..1191f57f53ae 100644
--- a/arch/csky/mm/highmem.c
+++ b/arch/csky/mm/highmem.c
@@ -25,12 +25,11 @@  EXPORT_SYMBOL(kmap);
 void *kmap_atomic(struct page *page)
 {
 	unsigned long vaddr;
+	void *addr = kmap_atomic_fast(page);
 	int idx, type;
 
-	preempt_disable();
-	pagefault_disable();
-	if (!PageHighMem(page))
-		return page_address(page);
+	if (addr)
+		return addr;
 
 	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR*smp_processor_id();
diff --git a/arch/microblaze/mm/highmem.c b/arch/microblaze/mm/highmem.c
index d7569f77fa15..99fdf826edc2 100644
--- a/arch/microblaze/mm/highmem.c
+++ b/arch/microblaze/mm/highmem.c
@@ -36,13 +36,11 @@  void *kmap_atomic_prot(struct page *page, pgprot_t prot)
 {
 
 	unsigned long vaddr;
+	void *addr = kmap_atomic_fast(page);
 	int idx, type;
 
-	preempt_disable();
-	pagefault_disable();
-	if (!PageHighMem(page))
-		return page_address(page);
-
+	if (addr)
+		return addr;
 
 	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR*smp_processor_id();
diff --git a/arch/mips/mm/highmem.c b/arch/mips/mm/highmem.c
index c3c9fe962f0f..ba03ca75d4a1 100644
--- a/arch/mips/mm/highmem.c
+++ b/arch/mips/mm/highmem.c
@@ -33,12 +33,11 @@  EXPORT_SYMBOL(kmap);
 void *kmap_atomic(struct page *page)
 {
 	unsigned long vaddr;
+	void *addr = kmap_atomic_fast(page);
 	int idx, type;
 
-	preempt_disable();
-	pagefault_disable();
-	if (!PageHighMem(page))
-		return page_address(page);
+	if (addr)
+		return addr;
 
 	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR*smp_processor_id();
diff --git a/arch/nds32/mm/highmem.c b/arch/nds32/mm/highmem.c
index f9348bec0ecb..4aabde586489 100644
--- a/arch/nds32/mm/highmem.c
+++ b/arch/nds32/mm/highmem.c
@@ -14,13 +14,12 @@  void *kmap_atomic(struct page *page)
 {
 	unsigned int idx;
 	unsigned long vaddr, pte;
+	void *addr = kmap_atomic_fast(page);
 	int type;
 	pte_t *ptep;
 
-	preempt_disable();
-	pagefault_disable();
-	if (!PageHighMem(page))
-		return page_address(page);
+	if (addr)
+		return addr;
 
 	type = kmap_atomic_idx_push();
 
diff --git a/arch/powerpc/mm/highmem.c b/arch/powerpc/mm/highmem.c
index 320c1672b2ae..cdf5b716801a 100644
--- a/arch/powerpc/mm/highmem.c
+++ b/arch/powerpc/mm/highmem.c
@@ -33,12 +33,11 @@ 
 void *kmap_atomic_prot(struct page *page, pgprot_t prot)
 {
 	unsigned long vaddr;
+	void *addr = kmap_atomic_fast(page);
 	int idx, type;
 
-	preempt_disable();
-	pagefault_disable();
-	if (!PageHighMem(page))
-		return page_address(page);
+	if (addr)
+		return addr;
 
 	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR*smp_processor_id();
diff --git a/arch/sparc/mm/highmem.c b/arch/sparc/mm/highmem.c
index d4a80adea7e5..178641805567 100644
--- a/arch/sparc/mm/highmem.c
+++ b/arch/sparc/mm/highmem.c
@@ -56,12 +56,11 @@  void __init kmap_init(void)
 void *kmap_atomic(struct page *page)
 {
 	unsigned long vaddr;
+	void *addr = kmap_atomic_fast(page);
 	long idx, type;
 
-	preempt_disable();
-	pagefault_disable();
-	if (!PageHighMem(page))
-		return page_address(page);
+	if (addr)
+		return addr;
 
 	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR*smp_processor_id();
diff --git a/arch/x86/mm/highmem_32.c b/arch/x86/mm/highmem_32.c
index c4ebfd0ae401..34770499b0ff 100644
--- a/arch/x86/mm/highmem_32.c
+++ b/arch/x86/mm/highmem_32.c
@@ -15,13 +15,11 @@ 
 void *kmap_atomic_prot(struct page *page, pgprot_t prot)
 {
 	unsigned long vaddr;
+	void *addr = kmap_atomic_fast(page);
 	int idx, type;
 
-	preempt_disable();
-	pagefault_disable();
-
-	if (!PageHighMem(page))
-		return page_address(page);
+	if (addr)
+		return addr;
 
 	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR*smp_processor_id();
diff --git a/arch/xtensa/mm/highmem.c b/arch/xtensa/mm/highmem.c
index 184ceadccc1a..38c14e0b578c 100644
--- a/arch/xtensa/mm/highmem.c
+++ b/arch/xtensa/mm/highmem.c
@@ -41,11 +41,10 @@  void *kmap_atomic(struct page *page)
 {
 	enum fixed_addresses idx;
 	unsigned long vaddr;
+	void *addr = kmap_atomic_fast(page);
 
-	preempt_disable();
-	pagefault_disable();
-	if (!PageHighMem(page))
-		return page_address(page);
+	if (addr)
+		return addr;
 
 	idx = kmap_idx(kmap_atomic_idx_push(),
 		       DCACHE_ALIAS(page_to_phys(page)));
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 1a3b7690c78c..eee53e151900 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -60,6 +60,15 @@  static inline void kunmap(struct page *page)
 	kunmap_high(page);
 }
 
+static inline void *kmap_atomic_fast(struct page *page)
+{
+	preempt_disable();
+	pagefault_disable();
+	if (!PageHighMem(page))
+		return page_address(page);
+	return NULL;
+}
+
 /* declarations for linux/mm/highmem.c */
 unsigned int nr_free_highpages(void);
 extern atomic_long_t _totalhigh_pages;