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McKenney" To: linux-kernel@vger.kernel.org Subject: [PATCH RFC 12/26] arm64: Remove spin_unlock_wait() arch-specific definitions Date: Thu, 29 Jun 2017 17:01:20 -0700 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20170629235918.GA6445@linux.vnet.ibm.com> References: <20170629235918.GA6445@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17063000-2213-0000-0000-000001ECC88A X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007295; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000214; SDB=6.00880606; UDB=6.00439011; IPR=6.00660759; BA=6.00005447; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00016015; XFM=3.00000015; UTC=2017-06-30 00:01:41 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17063000-2214-0000-0000-000056B3147E Message-Id: <1498780894-8253-12-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-06-29_17:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=3 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1706290384 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170629_170205_856503_7FB7C7E3 X-CRM114-Status: GOOD ( 17.66 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, parri.andrea@gmail.com, dave@stgolabs.net, manfred@colorfullife.com, arnd@arndb.de, peterz@infradead.org, netdev@vger.kernel.org, will.deacon@arm.com, oleg@redhat.com, mingo@redhat.com, netfilter-devel@vger.kernel.org, Catalin Marinas , tj@kernel.org, stern@rowland.harvard.edu, akpm@linux-foundation.org, "Paul E. McKenney" , torvalds@linux-foundation.org, linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP 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 commit therefore removes the underlying arch-specific arch_spin_unlock_wait(). Signed-off-by: Paul E. McKenney Cc: Catalin Marinas Cc: Will Deacon Cc: Cc: Peter Zijlstra Cc: Alan Stern Cc: Andrea Parri Cc: Linus Torvalds Acked-by: Will Deacon --- arch/arm64/include/asm/spinlock.h | 58 ++++----------------------------------- 1 file changed, 5 insertions(+), 53 deletions(-) diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h index cae331d553f8..f445bd7f2b9f 100644 --- a/arch/arm64/include/asm/spinlock.h +++ b/arch/arm64/include/asm/spinlock.h @@ -26,58 +26,6 @@ * The memory barriers are implicit with the load-acquire and store-release * instructions. */ -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - unsigned int tmp; - arch_spinlock_t lockval; - u32 owner; - - /* - * Ensure prior spin_lock operations to other locks have completed - * on this CPU before we test whether "lock" is locked. - */ - smp_mb(); - owner = READ_ONCE(lock->owner) << 16; - - asm volatile( -" sevl\n" -"1: wfe\n" -"2: ldaxr %w0, %2\n" - /* Is the lock free? */ -" eor %w1, %w0, %w0, ror #16\n" -" cbz %w1, 3f\n" - /* Lock taken -- has there been a subsequent unlock->lock transition? */ -" eor %w1, %w3, %w0, lsl #16\n" -" cbz %w1, 1b\n" - /* - * The owner has been updated, so there was an unlock->lock - * transition that we missed. That means we can rely on the - * store-release of the unlock operation paired with the - * load-acquire of the lock operation to publish any of our - * previous stores to the new lock owner and therefore don't - * need to bother with the writeback below. - */ -" b 4f\n" -"3:\n" - /* - * Serialise against any concurrent lockers by writing back the - * unlocked lock value - */ - ARM64_LSE_ATOMIC_INSN( - /* LL/SC */ -" stxr %w1, %w0, %2\n" - __nops(2), - /* LSE atomics */ -" mov %w1, %w0\n" -" cas %w0, %w0, %2\n" -" eor %w1, %w1, %w0\n") - /* Somebody else wrote to the lock, GOTO 10 and reload the value */ -" cbnz %w1, 2b\n" -"4:" - : "=&r" (lockval), "=&r" (tmp), "+Q" (*lock) - : "r" (owner) - : "memory"); -} #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) @@ -176,7 +124,11 @@ static inline int arch_spin_value_unlocked(arch_spinlock_t lock) static inline int arch_spin_is_locked(arch_spinlock_t *lock) { - smp_mb(); /* See arch_spin_unlock_wait */ + /* + * Ensure prior spin_lock operations to other locks have completed + * on this CPU before we test whether "lock" is locked. + */ + smp_mb(); /* ^^^ */ return !arch_spin_value_unlocked(READ_ONCE(*lock)); }