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* atomic: implement generic atomic_dec_if_positive()Shaohua Li2012-10-091-0/+25
| | | | | | | | | | | | | | | | | | | | | The x86 implementation of atomic_dec_if_positive is quite generic, so make it available to all architectures. This is needed for "swap: add a simple detector for inappropriate swapin readahead". [akpm@linux-foundation.org: do the "#define foo foo" trick in the conventional manner] Signed-off-by: Shaohua Li <shli@fusionio.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: Rik van Riel <riel@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michal Simek <monstr@monstr.eu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* atomic: Allow atomic_inc_not_zero to be overriddenAnton Blanchard2012-03-071-0/+2
| | | | | | | | | We want to implement a ppc64 specific version of atomic_inc_not_zero so wrap it in an ifdef to allow it to be overridden. Signed-off-by: Anton Blanchard <anton@samba.org> Acked-by: Mike Frysinger <vapier@gentoo.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* atomic: Update comments in atomic.hArun Sharma2011-07-261-0/+1
| | | | | | | | | | | | | | This clarifies the differences between <linux/atomic.h> and <asm-generic/atomic.h> Signed-off-by: Arun Sharma <asharma@fb.com> Suggested-by: Mike Frysinger <vapier.adi@gmail.com> Cc: 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>
* atomic: cleanup asm-generic atomic*.h inclusionArun Sharma2011-07-261-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | After changing all consumers of atomics to include <linux/atomic.h>, we ran into some compile time errors due to this dependency chain: linux/atomic.h -> asm/atomic.h -> asm-generic/atomic-long.h where atomic-long.h could use funcs defined later in linux/atomic.h without a prototype. This patches moves the code that includes asm-generic/atomic*.h to linux/atomic.h. Archs that need <asm-generic/atomic64.h> need to select CONFIG_GENERIC_ATOMIC64 from now on (some of them used to include it unconditionally). Compile tested on i386 and x86_64 with allnoconfig. Signed-off-by: Arun Sharma <asharma@fb.com> Cc: 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>
* atomic: move atomic_add_unless to generic codeArun Sharma2011-07-261-0/+14
| | | | | | | | | | | | | | 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>
* atomic: use <linux/atomic.h>Arun Sharma2011-07-261-0/+9
| | | | | | | | | | | | | | This allows us to move duplicated code in <asm/atomic.h> (atomic_inc_not_zero() for now) to <linux/atomic.h> Signed-off-by: Arun Sharma <asharma@fb.com> Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> 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>
* lockless get_write_access/deny_write_accessAl Viro2011-07-201-0/+26
| | | | | | new helpers: atomic_inc_unless_negative()/atomic_dec_unless_positive() Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* atomic: Add atomic_or()Paul E. McKenney2011-05-281-0/+13
| | | | | | | | | An atomic_or() function is needed by TREE_RCU to avoid deadlock, so add a generic version. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* atomic: add atomic_inc_not_zero_hint()Eric Dumazet2010-11-121-0/+37
Followup of perf tools session in Netfilter WorkShop 2010 In the network stack we make high usage of atomic_inc_not_zero() in contexts we know the probable value of atomic before increment (2 for udp sockets for example) Using a special version of atomic_inc_not_zero() giving this hint can help processor to use less bus transactions. On x86 (MESI protocol) for example, this avoids entering Shared state, because "lock cmpxchg" issues an RFO (Read For Ownership) akpm: Adds a new include/linux/atomic.h. This means that new code should henceforth include linux/atomic.h and not asm/atomic.h. The presence of include/linux/atomic.h will in fact cause checkpatch.pl to warn about use of asm/atomic.h. The new include/linux/atomic.h becomes the place where arch-neutral atomic_t code should be placed. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Andi Kleen <andi@firstfloor.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: David Miller <davem@davemloft.net> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Nick Piggin <npiggin@kernel.dk> Reviewed-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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