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2014-10-03locking,arch: Use ACCESS_ONCE() instead of cast to volatile in atomic_read()Pranith Kumar
Use the much more reader friendly ACCESS_ONCE() instead of the cast to volatile. This is purely a stylistic change. Signed-off-by: Pranith Kumar <bobby.prani@gmail.com> Acked-by: Jesper Nilsson <jesper.nilsson@axis.com> Acked-by: Hans-Christian Egtvedt <egtvedt@samfundet.no> Acked-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: linux-arch@vger.kernel.org Link: http://lkml.kernel.org/r/1411482607-20948-1-git-send-email-bobby.prani@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-12-04x86, bitops: Correct the assembly constraints to testing bitopsH. Peter Anvin
In checkin: 0c44c2d0f459 x86: Use asm goto to implement better modify_and_test() functions the various functions which do modify and test were unified and optimized using "asm goto". However, this change missed the detail that the bitops require an "Ir" constraint rather than an "er" constraint ("I" = integer constant from 0-31, "e" = signed 32-bit integer constant). This would cause code to miscompile if these functions were used on constant bit positions 32-255 and the build to fail if used on constant bit positions above 255. Add the constraints as a parameter to the GEN_BINARY_RMWcc() macro to avoid this problem. Reported-by: Jesse Brandeburg <jesse.brandeburg@intel.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/529E8719.4070202@zytor.com
2013-09-25x86: Use asm goto to implement better modify_and_test() functionsPeter Zijlstra
Linus suggested using asm goto to get rid of the typical SETcc + TEST instruction pair -- which also clobbers an extra register -- for our typical modify_and_test() functions. Because asm goto doesn't allow output fields it has to include an unconditinal memory clobber when it changes a memory variable to force a reload. Luckily all atomic ops already imply a compiler barrier to go along with their memory barrier semantics. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-0mtn9siwbeo1d33bap1422se@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2011-08-29x86: Use xadd helper more widelyJeremy Fitzhardinge
This covers the trivial cases from open-coded xadd to the xadd macros. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Link: http://lkml.kernel.org/r/4E5BCC40.3030501@goop.org Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2011-07-26atomic: move atomic_add_unless to generic codeArun Sharma
This is in preparation for more generic atomic primitives based on __atomic_add_unless. Signed-off-by: Arun Sharma <asharma@fb.com> Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com> Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net> Acked-by: Mike Frysinger <vapier@gentoo.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-05-18Merge branch 'x86-atomic-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'x86-atomic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86: Fix LOCK_PREFIX_HERE for uniprocessor build x86, atomic64: In selftest, distinguish x86-64 from 586+ x86-32: Fix atomic64_inc_not_zero return value convention lib: Fix atomic64_inc_not_zero test lib: Fix atomic64_add_unless return value convention x86-32: Fix atomic64_add_unless return value convention lib: Fix atomic64_add_unless test x86: Implement atomic[64]_dec_if_positive() lib: Only test atomic64_dec_if_positive on archs having it x86-32: Rewrite 32-bit atomic64 functions in assembly lib: Add self-test for atomic64_t x86-32: Allow UP/SMP lock replacement in cmpxchg64 x86: Add support for lock prefix in alternatives
2010-05-17atomic_t: Cast to volatile when accessing atomic variablesAnton Blanchard
In preparation for removing volatile from the atomic_t definition, this patch adds a volatile cast to all the atomic read functions. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-01x86: Implement atomic[64]_dec_if_positive()Luca Barbieri
Add support for atomic_dec_if_positive(), and atomic64_dec_if_positive() for x86-64. atomic64_dec_if_positive() for x86-32 was already implemented in a previous patch. Signed-off-by: Luca Barbieri <luca@luca-barbieri.com> LKML-Reference: <1267183361-20775-2-git-send-email-luca@luca-barbieri.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2010-01-07x86: Split atomic64_t functions into seperate headersBrian Gerst
Split atomic64_t functions out into separate headers, since they will not be practical to merge between 32 and 64 bits. Signed-off-by: Brian Gerst <brgerst@gmail.com> LKML-Reference: <1262883215-4034-2-git-send-email-brgerst@gmail.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>