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authorHitoshi Mitake <mitake@dcl.info.waseda.ac.jp>2012-02-07 11:45:33 +0900
committerLinus Torvalds <torvalds@linux-foundation.org>2012-02-21 16:47:28 -0800
commit797a796a13df6b84a4791e57306737059b5b2384 (patch)
tree400d13deef98fdf3fc893e9e55f208c5716b8ba9 /fs/select.c
parent27e74da9800289e69ba907777df1e2085231eff7 (diff)
asm-generic: architecture independent readq/writeq for 32bit environment
This provides unified readq()/writeq() helper functions for 32-bit drivers. For some cases, readq/writeq without atomicity is harmful, and order of io access has to be specified explicitly. So in this patch, new two header files which contain non-atomic readq/writeq are added. - <asm-generic/io-64-nonatomic-lo-hi.h> provides non-atomic readq/ writeq with the order of lower address -> higher address - <asm-generic/io-64-nonatomic-hi-lo.h> provides non-atomic readq/ writeq with reversed order This allows us to remove some readq()s that were added drivers when the default non-atomic ones were removed in commit dbee8a0affd5 ("x86: remove 32-bit versions of readq()/writeq()") The drivers which need readq/writeq but can do with the non-atomic ones must add the line: #include <asm-generic/io-64-nonatomic-lo-hi.h> /* or hi-lo.h */ But this will be nop in 64-bit environments, and no other #ifdefs are required. So I believe that this patch can solve the problem of 1. driver-specific readq/writeq 2. atomicity and order of io access This patch is tested with building allyesconfig and allmodconfig as ARCH=x86 and ARCH=i386 on top of tip/master. Cc: Kashyap Desai <Kashyap.Desai@lsi.com> Cc: Len Brown <lenb@kernel.org> Cc: Ravi Anand <ravi.anand@qlogic.com> Cc: Vikas Chaudhary <vikas.chaudhary@qlogic.com> Cc: Matthew Garrett <mjg@redhat.com> Cc: Jason Uhlenkott <juhlenko@akamai.com> Cc: James Bottomley <James.Bottomley@parallels.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Roland Dreier <roland@purestorage.com> Cc: James Bottomley <jbottomley@parallels.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Matthew Wilcox <matthew.r.wilcox@intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Hitoshi Mitake <h.mitake@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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