diff options
author | 2020-06-04 16:47:42 -0700 | |
---|---|---|
committer | 2020-06-04 19:06:22 -0700 | |
commit | 78b6d91ec7bbfc5bcc2dd05bb2cf13c9de1dc7cd (patch) | |
tree | 63a7267f0fd2bac5dabc6cfd189cbc9cbd820f6c /include/linux/highmem.h | |
parent | {x86,powerpc,microblaze}/kmap: move preempt disable (diff) | |
download | linux-78b6d91ec7bbfc5bcc2dd05bb2cf13c9de1dc7cd.tar.gz linux-78b6d91ec7bbfc5bcc2dd05bb2cf13c9de1dc7cd.tar.bz2 linux-78b6d91ec7bbfc5bcc2dd05bb2cf13c9de1dc7cd.zip |
arch/kmap_atomic: consolidate duplicate code
Every arch has the same code to ensure atomic operations and a check for
!HIGHMEM page.
Remove the duplicate code by defining a core kmap_atomic() which only
calls the arch specific kmap_atomic_high() when the page is high memory.
[akpm@linux-foundation.org: coding style fixes]
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian König <christian.koenig@amd.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200507150004.1423069-7-ira.weiny@intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/highmem.h')
-rw-r--r-- | include/linux/highmem.h | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 216a647ed7db..d2209ae8be99 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -32,6 +32,7 @@ static inline void invalidate_kernel_vmap_range(void *vaddr, int size) #include <asm/kmap_types.h> #ifdef CONFIG_HIGHMEM +extern void *kmap_atomic_high(struct page *page); #include <asm/highmem.h> #ifndef ARCH_HAS_KMAP_FLUSH_TLB @@ -62,6 +63,28 @@ static inline void kunmap(struct page *page) kunmap_high(page); } +/* + * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because + * no global lock is needed and because the kmap code must perform a global TLB + * invalidation when the kmap pool wraps. + * + * However when holding an atomic kmap is is not legal to sleep, so atomic + * kmaps are appropriate for short, tight code paths only. + * + * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap + * gives a more generic (and caching) interface. But kmap_atomic can + * be used in IRQ contexts, so in some (very limited) cases we need + * it. + */ +static inline void *kmap_atomic(struct page *page) +{ + preempt_disable(); + pagefault_disable(); + if (!PageHighMem(page)) + return page_address(page); + return kmap_atomic_high(page); +} + /* declarations for linux/mm/highmem.c */ unsigned int nr_free_highpages(void); extern atomic_long_t _totalhigh_pages; |