Hi Jason, [auto build test ERROR on v4.6-rc3] [also build test ERROR on next-20160412] [cannot apply to tip/core/locking] [if your patch is applied to the wrong git tree, please drop us a note to help improving the system]
url: https://github.com/0day-ci/linux/commits/Jason-Low/MCS-spinlock-Use-smp_cond_load_acquire/20160413-053726 config: i386-randconfig-s0-201615 (attached as .config) reproduce: # save the attached .config to linux build tree make ARCH=i386 All error/warnings (new ones prefixed by >>): In file included from kernel/locking/qspinlock.c:70:0: kernel/locking/mcs_spinlock.h: In function 'mcs_spin_lock': >> kernel/locking/mcs_spinlock.h:31:2: error: implicit declaration of function >> 'smp_cond_load_acquire' [-Werror=implicit-function-declaration] smp_cond_load_acquire(&l, VAL); \ ^ >> kernel/locking/mcs_spinlock.h:91:2: note: in expansion of macro >> 'arch_mcs_spin_lock_contended' arch_mcs_spin_lock_contended(&node->locked); ^ >> kernel/locking/mcs_spinlock.h:31:24: error: lvalue required as unary '&' >> operand smp_cond_load_acquire(&l, VAL); \ ^ >> kernel/locking/mcs_spinlock.h:91:2: note: in expansion of macro >> 'arch_mcs_spin_lock_contended' arch_mcs_spin_lock_contended(&node->locked); ^ >> kernel/locking/mcs_spinlock.h:31:28: error: 'VAL' undeclared (first use in >> this function) smp_cond_load_acquire(&l, VAL); \ ^ >> kernel/locking/mcs_spinlock.h:91:2: note: in expansion of macro >> 'arch_mcs_spin_lock_contended' arch_mcs_spin_lock_contended(&node->locked); ^ kernel/locking/mcs_spinlock.h:31:28: note: each undeclared identifier is reported only once for each function it appears in smp_cond_load_acquire(&l, VAL); \ ^ >> kernel/locking/mcs_spinlock.h:91:2: note: in expansion of macro >> 'arch_mcs_spin_lock_contended' arch_mcs_spin_lock_contended(&node->locked); ^ kernel/locking/qspinlock.c: In function 'native_queued_spin_lock_slowpath': >> kernel/locking/mcs_spinlock.h:31:24: error: lvalue required as unary '&' >> operand smp_cond_load_acquire(&l, VAL); \ ^ >> kernel/locking/qspinlock.c:411:3: note: in expansion of macro >> 'arch_mcs_spin_lock_contended' arch_mcs_spin_lock_contended(&node->locked); ^ >> kernel/locking/mcs_spinlock.h:31:28: error: 'VAL' undeclared (first use in >> this function) smp_cond_load_acquire(&l, VAL); \ ^ >> kernel/locking/qspinlock.c:411:3: note: in expansion of macro >> 'arch_mcs_spin_lock_contended' arch_mcs_spin_lock_contended(&node->locked); ^ kernel/locking/qspinlock.c: In function '__pv_queued_spin_lock_slowpath': >> kernel/locking/mcs_spinlock.h:31:24: error: lvalue required as unary '&' >> operand smp_cond_load_acquire(&l, VAL); \ ^ >> kernel/locking/qspinlock.c:411:3: note: in expansion of macro >> 'arch_mcs_spin_lock_contended' arch_mcs_spin_lock_contended(&node->locked); ^ >> kernel/locking/mcs_spinlock.h:31:28: error: 'VAL' undeclared (first use in >> this function) smp_cond_load_acquire(&l, VAL); \ ^ >> kernel/locking/qspinlock.c:411:3: note: in expansion of macro >> 'arch_mcs_spin_lock_contended' arch_mcs_spin_lock_contended(&node->locked); ^ cc1: some warnings being treated as errors vim +/smp_cond_load_acquire +31 kernel/locking/mcs_spinlock.h 25 * Using smp_cond_load_acquire() provides the acquire semantics 26 * required so that subsequent operations happen after the 27 * lock is acquired. 28 */ 29 #define arch_mcs_spin_lock_contended(l) \ 30 do { \ > 31 smp_cond_load_acquire(&l, VAL); \ 32 } while (0) 33 #endif 34 35 #ifndef arch_mcs_spin_unlock_contended 36 /* 37 * smp_store_release() provides a memory barrier to ensure all 38 * operations in the critical section has been completed before 39 * unlocking. 40 */ 41 #define arch_mcs_spin_unlock_contended(l) \ 42 smp_store_release((l), 1) 43 #endif 44 45 /* 46 * Note: the smp_load_acquire/smp_store_release pair is not 47 * sufficient to form a full memory barrier across 48 * cpus for many architectures (except x86) for mcs_unlock and mcs_lock. 49 * For applications that need a full barrier across multiple cpus 50 * with mcs_unlock and mcs_lock pair, smp_mb__after_unlock_lock() should be 51 * used after mcs_lock. 52 */ 53 54 /* 55 * In order to acquire the lock, the caller should declare a local node and 56 * pass a reference of the node to this function in addition to the lock. 57 * If the lock has already been acquired, then this will proceed to spin 58 * on this node->locked until the previous lock holder sets the node->locked 59 * in mcs_spin_unlock(). 60 */ 61 static inline 62 void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node) 63 { 64 struct mcs_spinlock *prev; 65 66 /* Init node */ 67 node->locked = 0; 68 node->next = NULL; 69 70 /* 71 * We rely on the full barrier with global transitivity implied by the 72 * below xchg() to order the initialization stores above against any 73 * observation of @node. And to provide the ACQUIRE ordering associated 74 * with a LOCK primitive. 75 */ 76 prev = xchg(lock, node); 77 if (likely(prev == NULL)) { 78 /* 79 * Lock acquired, don't need to set node->locked to 1. Threads 80 * only spin on its own node->locked value for lock acquisition. 81 * However, since this thread can immediately acquire the lock 82 * and does not proceed to spin on its own node->locked, this 83 * value won't be used. If a debug mode is needed to 84 * audit lock status, then set node->locked value here. 85 */ 86 return; 87 } 88 WRITE_ONCE(prev->next, node); 89 90 /* Wait until the lock holder passes the lock down. */ > 91 arch_mcs_spin_lock_contended(&node->locked); 92 } 93 94 /* --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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