| 1 | /* |
| 2 | * SPDX-License-Identifier: MIT |
| 3 | * |
| 4 | * Copyright © 2016 Intel Corporation |
| 5 | */ |
| 6 | |
| 7 | #include <linux/dma-fence-array.h> |
| 8 | #include <linux/jiffies.h> |
| 9 | |
| 10 | #include "gt/intel_engine.h" |
| 11 | |
| 12 | #include "i915_gem_ioctls.h" |
| 13 | #include "i915_gem_object.h" |
| 14 | |
| 15 | static long |
| 16 | i915_gem_object_wait_fence(struct dma_fence *fence, |
| 17 | unsigned int flags, |
| 18 | long timeout) |
| 19 | { |
| 20 | BUILD_BUG_ON(I915_WAIT_INTERRUPTIBLE != 0x1); |
| 21 | |
| 22 | if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) |
| 23 | return timeout; |
| 24 | |
| 25 | if (dma_fence_is_i915(fence)) |
| 26 | return i915_request_wait(to_request(fence), flags, timeout); |
| 27 | |
| 28 | return dma_fence_wait_timeout(fence, |
| 29 | flags & I915_WAIT_INTERRUPTIBLE, |
| 30 | timeout); |
| 31 | } |
| 32 | |
| 33 | static long |
| 34 | i915_gem_object_wait_reservation(struct reservation_object *resv, |
| 35 | unsigned int flags, |
| 36 | long timeout) |
| 37 | { |
| 38 | struct dma_fence *excl; |
| 39 | bool prune_fences = false; |
| 40 | |
| 41 | if (flags & I915_WAIT_ALL) { |
| 42 | struct dma_fence **shared; |
| 43 | unsigned int count, i; |
| 44 | int ret; |
| 45 | |
| 46 | ret = reservation_object_get_fences_rcu(resv, |
| 47 | &excl, &count, &shared); |
| 48 | if (ret) |
| 49 | return ret; |
| 50 | |
| 51 | for (i = 0; i < count; i++) { |
| 52 | timeout = i915_gem_object_wait_fence(shared[i], |
| 53 | flags, timeout); |
| 54 | if (timeout < 0) |
| 55 | break; |
| 56 | |
| 57 | dma_fence_put(shared[i]); |
| 58 | } |
| 59 | |
| 60 | for (; i < count; i++) |
| 61 | dma_fence_put(shared[i]); |
| 62 | kfree(shared); |
| 63 | |
| 64 | /* |
| 65 | * If both shared fences and an exclusive fence exist, |
| 66 | * then by construction the shared fences must be later |
| 67 | * than the exclusive fence. If we successfully wait for |
| 68 | * all the shared fences, we know that the exclusive fence |
| 69 | * must all be signaled. If all the shared fences are |
| 70 | * signaled, we can prune the array and recover the |
| 71 | * floating references on the fences/requests. |
| 72 | */ |
| 73 | prune_fences = count && timeout >= 0; |
| 74 | } else { |
| 75 | excl = reservation_object_get_excl_rcu(resv); |
| 76 | } |
| 77 | |
| 78 | if (excl && timeout >= 0) |
| 79 | timeout = i915_gem_object_wait_fence(excl, flags, timeout); |
| 80 | |
| 81 | dma_fence_put(excl); |
| 82 | |
| 83 | /* |
| 84 | * Opportunistically prune the fences iff we know they have *all* been |
| 85 | * signaled. |
| 86 | */ |
| 87 | if (prune_fences && reservation_object_trylock(resv)) { |
| 88 | if (reservation_object_test_signaled_rcu(resv, true)) |
| 89 | reservation_object_add_excl_fence(resv, NULL); |
| 90 | reservation_object_unlock(resv); |
| 91 | } |
| 92 | |
| 93 | return timeout; |
| 94 | } |
| 95 | |
| 96 | static void __fence_set_priority(struct dma_fence *fence, |
| 97 | const struct i915_sched_attr *attr) |
| 98 | { |
| 99 | struct i915_request *rq; |
| 100 | struct intel_engine_cs *engine; |
| 101 | |
| 102 | if (dma_fence_is_signaled(fence) || !dma_fence_is_i915(fence)) |
| 103 | return; |
| 104 | |
| 105 | rq = to_request(fence); |
| 106 | engine = rq->engine; |
| 107 | |
| 108 | local_bh_disable(); |
| 109 | rcu_read_lock(); /* RCU serialisation for set-wedged protection */ |
| 110 | if (engine->schedule) |
| 111 | engine->schedule(rq, attr); |
| 112 | rcu_read_unlock(); |
| 113 | local_bh_enable(); /* kick the tasklets if queues were reprioritised */ |
| 114 | } |
| 115 | |
| 116 | static void fence_set_priority(struct dma_fence *fence, |
| 117 | const struct i915_sched_attr *attr) |
| 118 | { |
| 119 | /* Recurse once into a fence-array */ |
| 120 | if (dma_fence_is_array(fence)) { |
| 121 | struct dma_fence_array *array = to_dma_fence_array(fence); |
| 122 | int i; |
| 123 | |
| 124 | for (i = 0; i < array->num_fences; i++) |
| 125 | __fence_set_priority(array->fences[i], attr); |
| 126 | } else { |
| 127 | __fence_set_priority(fence, attr); |
| 128 | } |
| 129 | } |
| 130 | |
| 131 | int |
| 132 | i915_gem_object_wait_priority(struct drm_i915_gem_object *obj, |
| 133 | unsigned int flags, |
| 134 | const struct i915_sched_attr *attr) |
| 135 | { |
| 136 | struct dma_fence *excl; |
| 137 | |
| 138 | if (flags & I915_WAIT_ALL) { |
| 139 | struct dma_fence **shared; |
| 140 | unsigned int count, i; |
| 141 | int ret; |
| 142 | |
| 143 | ret = reservation_object_get_fences_rcu(obj->base.resv, |
| 144 | &excl, &count, &shared); |
| 145 | if (ret) |
| 146 | return ret; |
| 147 | |
| 148 | for (i = 0; i < count; i++) { |
| 149 | fence_set_priority(shared[i], attr); |
| 150 | dma_fence_put(shared[i]); |
| 151 | } |
| 152 | |
| 153 | kfree(shared); |
| 154 | } else { |
| 155 | excl = reservation_object_get_excl_rcu(obj->base.resv); |
| 156 | } |
| 157 | |
| 158 | if (excl) { |
| 159 | fence_set_priority(excl, attr); |
| 160 | dma_fence_put(excl); |
| 161 | } |
| 162 | return 0; |
| 163 | } |
| 164 | |
| 165 | /** |
| 166 | * Waits for rendering to the object to be completed |
| 167 | * @obj: i915 gem object |
| 168 | * @flags: how to wait (under a lock, for all rendering or just for writes etc) |
| 169 | * @timeout: how long to wait |
| 170 | */ |
| 171 | int |
| 172 | i915_gem_object_wait(struct drm_i915_gem_object *obj, |
| 173 | unsigned int flags, |
| 174 | long timeout) |
| 175 | { |
| 176 | might_sleep(); |
| 177 | GEM_BUG_ON(timeout < 0); |
| 178 | |
| 179 | timeout = i915_gem_object_wait_reservation(obj->base.resv, |
| 180 | flags, timeout); |
| 181 | return timeout < 0 ? timeout : 0; |
| 182 | } |
| 183 | |
| 184 | static inline unsigned long nsecs_to_jiffies_timeout(const u64 n) |
| 185 | { |
| 186 | /* nsecs_to_jiffies64() does not guard against overflow */ |
| 187 | if (NSEC_PER_SEC % HZ && |
| 188 | div_u64(n, NSEC_PER_SEC) >= MAX_JIFFY_OFFSET / HZ) |
| 189 | return MAX_JIFFY_OFFSET; |
| 190 | |
| 191 | return min_t(u64, MAX_JIFFY_OFFSET, nsecs_to_jiffies64(n) + 1); |
| 192 | } |
| 193 | |
| 194 | static unsigned long to_wait_timeout(s64 timeout_ns) |
| 195 | { |
| 196 | if (timeout_ns < 0) |
| 197 | return MAX_SCHEDULE_TIMEOUT; |
| 198 | |
| 199 | if (timeout_ns == 0) |
| 200 | return 0; |
| 201 | |
| 202 | return nsecs_to_jiffies_timeout(timeout_ns); |
| 203 | } |
| 204 | |
| 205 | /** |
| 206 | * i915_gem_wait_ioctl - implements DRM_IOCTL_I915_GEM_WAIT |
| 207 | * @dev: drm device pointer |
| 208 | * @data: ioctl data blob |
| 209 | * @file: drm file pointer |
| 210 | * |
| 211 | * Returns 0 if successful, else an error is returned with the remaining time in |
| 212 | * the timeout parameter. |
| 213 | * -ETIME: object is still busy after timeout |
| 214 | * -ERESTARTSYS: signal interrupted the wait |
| 215 | * -ENONENT: object doesn't exist |
| 216 | * Also possible, but rare: |
| 217 | * -EAGAIN: incomplete, restart syscall |
| 218 | * -ENOMEM: damn |
| 219 | * -ENODEV: Internal IRQ fail |
| 220 | * -E?: The add request failed |
| 221 | * |
| 222 | * The wait ioctl with a timeout of 0 reimplements the busy ioctl. With any |
| 223 | * non-zero timeout parameter the wait ioctl will wait for the given number of |
| 224 | * nanoseconds on an object becoming unbusy. Since the wait itself does so |
| 225 | * without holding struct_mutex the object may become re-busied before this |
| 226 | * function completes. A similar but shorter * race condition exists in the busy |
| 227 | * ioctl |
| 228 | */ |
| 229 | int |
| 230 | i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file) |
| 231 | { |
| 232 | struct drm_i915_gem_wait *args = data; |
| 233 | struct drm_i915_gem_object *obj; |
| 234 | ktime_t start; |
| 235 | long ret; |
| 236 | |
| 237 | if (args->flags != 0) |
| 238 | return -EINVAL; |
| 239 | |
| 240 | obj = i915_gem_object_lookup(file, args->bo_handle); |
| 241 | if (!obj) |
| 242 | return -ENOENT; |
| 243 | |
| 244 | start = ktime_get(); |
| 245 | |
| 246 | ret = i915_gem_object_wait(obj, |
| 247 | I915_WAIT_INTERRUPTIBLE | |
| 248 | I915_WAIT_PRIORITY | |
| 249 | I915_WAIT_ALL, |
| 250 | to_wait_timeout(args->timeout_ns)); |
| 251 | |
| 252 | if (args->timeout_ns > 0) { |
| 253 | args->timeout_ns -= ktime_to_ns(ktime_sub(ktime_get(), start)); |
| 254 | if (args->timeout_ns < 0) |
| 255 | args->timeout_ns = 0; |
| 256 | |
| 257 | /* |
| 258 | * Apparently ktime isn't accurate enough and occasionally has a |
| 259 | * bit of mismatch in the jiffies<->nsecs<->ktime loop. So patch |
| 260 | * things up to make the test happy. We allow up to 1 jiffy. |
| 261 | * |
| 262 | * This is a regression from the timespec->ktime conversion. |
| 263 | */ |
| 264 | if (ret == -ETIME && !nsecs_to_jiffies(args->timeout_ns)) |
| 265 | args->timeout_ns = 0; |
| 266 | |
| 267 | /* Asked to wait beyond the jiffie/scheduler precision? */ |
| 268 | if (ret == -ETIME && args->timeout_ns) |
| 269 | ret = -EAGAIN; |
| 270 | } |
| 271 | |
| 272 | i915_gem_object_put(obj); |
| 273 | return ret; |
| 274 | } |