^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) // SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) #include <linux/export.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) #include <linux/lockref.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) #if USE_CMPXCHG_LOCKREF
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) * Note that the "cmpxchg()" reloads the "old" value for the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) * failure case.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) #define CMPXCHG_LOOP(CODE, SUCCESS) do { \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) int retry = 100; \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) struct lockref old; \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) BUILD_BUG_ON(sizeof(old) != 8); \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) old.lock_count = READ_ONCE(lockref->lock_count); \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) while (likely(arch_spin_value_unlocked(old.lock.rlock.raw_lock))) { \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) struct lockref new = old, prev = old; \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) CODE \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) old.lock_count = cmpxchg64_relaxed(&lockref->lock_count, \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) old.lock_count, \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) new.lock_count); \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) if (likely(old.lock_count == prev.lock_count)) { \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) SUCCESS; \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) } \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) if (!--retry) \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) break; \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) cpu_relax(); \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) } \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) } while (0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) #else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) #define CMPXCHG_LOOP(CODE, SUCCESS) do { } while (0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) #endif
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) * lockref_get - Increments reference count unconditionally
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) * @lockref: pointer to lockref structure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) * This operation is only valid if you already hold a reference
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) * to the object, so you know the count cannot be zero.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) void lockref_get(struct lockref *lockref)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) CMPXCHG_LOOP(
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) new.count++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) ,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) );
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) spin_lock(&lockref->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) lockref->count++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) spin_unlock(&lockref->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) EXPORT_SYMBOL(lockref_get);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) * lockref_get_not_zero - Increments count unless the count is 0 or dead
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) * @lockref: pointer to lockref structure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) * Return: 1 if count updated successfully or 0 if count was zero
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) int lockref_get_not_zero(struct lockref *lockref)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) int retval;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) CMPXCHG_LOOP(
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) new.count++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) if (old.count <= 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) ,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) return 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) );
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) spin_lock(&lockref->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) retval = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) if (lockref->count > 0) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) lockref->count++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) retval = 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) spin_unlock(&lockref->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) return retval;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) EXPORT_SYMBOL(lockref_get_not_zero);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) * lockref_put_not_zero - Decrements count unless count <= 1 before decrement
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) * @lockref: pointer to lockref structure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89) * Return: 1 if count updated successfully or 0 if count would become zero
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) int lockref_put_not_zero(struct lockref *lockref)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) int retval;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) CMPXCHG_LOOP(
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) new.count--;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) if (old.count <= 1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) ,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) return 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) );
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) spin_lock(&lockref->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) retval = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) if (lockref->count > 1) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) lockref->count--;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) retval = 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) spin_unlock(&lockref->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) return retval;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) EXPORT_SYMBOL(lockref_put_not_zero);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) * lockref_get_or_lock - Increments count unless the count is 0 or dead
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) * @lockref: pointer to lockref structure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) * Return: 1 if count updated successfully or 0 if count was zero
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) * and we got the lock instead.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) int lockref_get_or_lock(struct lockref *lockref)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) CMPXCHG_LOOP(
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) new.count++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) if (old.count <= 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) ,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) return 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) );
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) spin_lock(&lockref->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) if (lockref->count <= 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) lockref->count++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) spin_unlock(&lockref->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) return 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) EXPORT_SYMBOL(lockref_get_or_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) * lockref_put_return - Decrement reference count if possible
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) * @lockref: pointer to lockref structure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) * Decrement the reference count and return the new value.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) * If the lockref was dead or locked, return an error.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) int lockref_put_return(struct lockref *lockref)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) CMPXCHG_LOOP(
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) new.count--;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) if (old.count <= 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) return -1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) ,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) return new.count;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) );
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) return -1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) EXPORT_SYMBOL(lockref_put_return);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) * lockref_put_or_lock - decrements count unless count <= 1 before decrement
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) * @lockref: pointer to lockref structure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) * Return: 1 if count updated successfully or 0 if count <= 1 and lock taken
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) int lockref_put_or_lock(struct lockref *lockref)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) CMPXCHG_LOOP(
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) new.count--;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) if (old.count <= 1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) ,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) return 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) );
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) spin_lock(&lockref->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) if (lockref->count <= 1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) lockref->count--;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) spin_unlock(&lockref->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) return 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) EXPORT_SYMBOL(lockref_put_or_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) * lockref_mark_dead - mark lockref dead
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) * @lockref: pointer to lockref structure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) void lockref_mark_dead(struct lockref *lockref)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) assert_spin_locked(&lockref->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) lockref->count = -128;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) EXPORT_SYMBOL(lockref_mark_dead);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) * lockref_get_not_dead - Increments count unless the ref is dead
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) * @lockref: pointer to lockref structure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) * Return: 1 if count updated successfully or 0 if lockref was dead
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) int lockref_get_not_dead(struct lockref *lockref)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) int retval;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) CMPXCHG_LOOP(
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) new.count++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) if (old.count < 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) ,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) return 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) );
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) spin_lock(&lockref->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) retval = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213) if (lockref->count >= 0) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) lockref->count++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) retval = 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217) spin_unlock(&lockref->lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) return retval;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) EXPORT_SYMBOL(lockref_get_not_dead);
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
3 Commits
0 Branches
0 Tags
| Donate