There are still some leftovers of commit f59ca058
[locking, lib/atomic64: Annotate atomic64_lock::lock as raw]

[ tglx: Seems I picked the wrong version of that patch :( ]

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shan Hai <haishan.bai@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: http://lkml.kernel.org/r/20110914074924.GA16096@zhy


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

The spinlock protected atomic64 operations must be irq safe as they
are used in hard interrupt context and cannot be preempted on -rt:

 NIP [c068b218] rt_spin_lock_slowlock+0x78/0x3a8
  LR [c068b1e0] rt_spin_lock_slowlock+0x40/0x3a8
 Call Trace:
  [eb459b90] [c068b1e0] rt_spin_lock_slowlock+0x40/0x3a8 (unreliable)
  [eb459c20] [c068bdb0] rt_spin_lock+0x40/0x98
  [eb459c40] [c03d2a14] atomic64_read+0x48/0x84
  [eb459c60] [c001aaf4] perf_event_interrupt+0xec/0x28c
  [eb459d10] [c0010138] performance_monitor_exception+0x7c/0x150
  [eb459d30] [c0014170] ret_from_except_full+0x0/0x4c

So annotate it.

In mainline this change documents the low level nature of
the lock - otherwise there's no functional difference. Lockdep
and Sparse checking will work as usual.

Signed-off-by: Shan Hai <haishan.bai@gmail.com>
Reviewed-by: Yong Zhang <yong.zhang0@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

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>

atomic64_add_unless must return 1 if it perfomed the add and 0 otherwise.
The generic implementation did the opposite thing.

Reported-by: H. Peter Anvin <hpa@zytor.com>
Confirmed-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Luca Barbieri <luca@luca-barbieri.com>
LKML-Reference: <1267469749-11878-4-git-send-email-luca@luca-barbieri.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

The generic atomic64_t implementation in lib/ did not export the functions
it defined, which means that modules that use atomic64_t would not link on
platforms (such as 32-bit powerpc).  For example, trying to build a kernel
with CONFIG_NET_RDS on such a platform would fail with:

    ERROR: "atomic64_read" [net/rds/rds.ko] undefined!
    ERROR: "atomic64_set" [net/rds/rds.ko] undefined!

Fix this by exporting the atomic64_t functions to modules.  (I export the
entire API even if it's not all currently used by in-tree modules to avoid
having to continue fixing this in dribs and drabs)

Signed-off-by: Roland Dreier <rolandd@cisco.com>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Many processor architectures have no 64-bit atomic instructions, but
we need atomic64_t in order to support the perf_counter subsystem.

This adds an implementation of 64-bit atomic operations using hashed
spinlocks to provide atomicity.  For each atomic operation, the address
of the atomic64_t variable is hashed to an index into an array of 16
spinlocks.  That spinlock is taken (with interrupts disabled) around the
operation, which can then be coded non-atomically within the lock.

On UP, all the spinlock manipulation goes away and we simply disable
interrupts around each operation.  In fact gcc eliminates the whole
atomic64_lock variable as well.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>