[PATCH v3 0/9] Remove spin_unlock_wait()

From: Paul E. McKenney
Date: Fri Jul 07 2017 - 15:27:15 EST


Hello!

There is no agreed-upon definition of spin_unlock_wait()'s semantics,
and it appears that all callers could do just as well with a lock/unlock
pair. This series therefore removes spin_unlock_wait() and changes
its users to instead use a lock/unlock pair. The commits are as follows,
in three groups:

1-7. Change uses of spin_unlock_wait() and raw_spin_unlock_wait()
to instead use a spin_lock/spin_unlock pair. These may be
applied in any order, but must be applied before any later
commits in this series. The commit logs state why I believe
that these commits won't noticeably degrade performance.

8. Remove core-kernel definitions for spin_unlock_wait() and
raw_spin_unlock_wait().

9. Remove arch-specific definitions of arch_spin_unlock_wait().

Changes since v2:

o Add comment-only update from Manfred.

Changes since v1:

o Disable interrupts where needed, thus avoiding embarrassing
interrupt-based self-deadlocks.

o Substitute Manfred's patch for contrack_lock (#1 above).

o Substitute Oleg's patch for task_work (#2 above).

o Use more efficient barrier based on Arnd Bergmann feedback.

o Merge the arch commits.

Thanx, Paul

------------------------------------------------------------------------

arch/alpha/include/asm/spinlock.h | 5 -
arch/arc/include/asm/spinlock.h | 5 -
arch/arm/include/asm/spinlock.h | 16 ----
arch/arm64/include/asm/spinlock.h | 58 +----------------
arch/blackfin/include/asm/spinlock.h | 5 -
arch/hexagon/include/asm/spinlock.h | 5 -
arch/ia64/include/asm/spinlock.h | 21 ------
arch/m32r/include/asm/spinlock.h | 5 -
arch/metag/include/asm/spinlock.h | 5 -
arch/mips/include/asm/spinlock.h | 16 ----
arch/mn10300/include/asm/spinlock.h | 5 -
arch/parisc/include/asm/spinlock.h | 7 --
arch/powerpc/include/asm/spinlock.h | 33 ---------
arch/s390/include/asm/spinlock.h | 7 --
arch/sh/include/asm/spinlock-cas.h | 5 -
arch/sh/include/asm/spinlock-llsc.h | 5 -
arch/sparc/include/asm/spinlock_32.h | 5 -
arch/sparc/include/asm/spinlock_64.h | 5 -
arch/tile/include/asm/spinlock_32.h | 2
arch/tile/include/asm/spinlock_64.h | 2
arch/tile/lib/spinlock_32.c | 23 ------
arch/tile/lib/spinlock_64.c | 22 ------
arch/xtensa/include/asm/spinlock.h | 5 -
drivers/ata/libata-eh.c | 8 --
include/asm-generic/qspinlock.h | 14 ----
include/linux/spinlock.h | 31 ---------
include/linux/spinlock_up.h | 6 -
ipc/sem.c | 3
kernel/exit.c | 3
kernel/locking/qspinlock.c | 117 -----------------------------------
kernel/sched/completion.c | 9 --
kernel/sched/core.c | 5 -
kernel/task_work.c | 8 --
net/netfilter/nf_conntrack_core.c | 52 ++++++++-------
34 files changed, 48 insertions(+), 475 deletions(-)