Hi Chris, Quoting Chris Wilson <ch...@chris-wilson.co.uk>:
On Thu, May 11, 2017 at 03:00:02PM -0500, Gustavo A. R. Silva wrote:Hello everybody, While looking into Coverity ID 1402035 I ran into the following piece of code at kernel/locking/test-ww_mutex.c:197: 197static int test_abba(bool resolve) 198{ 199 struct test_abba abba; 200 struct ww_acquire_ctx ctx; 201 int err, ret; 202 203 ww_mutex_init(&abba.a_mutex, &ww_class); 204 ww_mutex_init(&abba.b_mutex, &ww_class); 205 INIT_WORK_ONSTACK(&abba.work, test_abba_work); 206 init_completion(&abba.a_ready); 207 init_completion(&abba.b_ready); 208 abba.resolve = resolve; 209 210 schedule_work(&abba.work); 211 212 ww_acquire_init(&ctx, &ww_class); 213 ww_mutex_lock(&abba.a_mutex, &ctx); 214 215 complete(&abba.a_ready); 216 wait_for_completion(&abba.b_ready); 217 218 err = ww_mutex_lock(&abba.b_mutex, &ctx); 219 if (resolve && err == -EDEADLK) { 220 ww_mutex_unlock(&abba.a_mutex); 221 ww_mutex_lock_slow(&abba.b_mutex, &ctx); 222 err = ww_mutex_lock(&abba.a_mutex, &ctx); 223 } 224 225 if (!err) 226 ww_mutex_unlock(&abba.b_mutex); 227 ww_mutex_unlock(&abba.a_mutex); 228 ww_acquire_fini(&ctx); 229 230 flush_work(&abba.work); 231 destroy_work_on_stack(&abba.work); 232 233 ret = 0; 234 if (resolve) { 235 if (err || abba.result) { 236 pr_err("%s: failed to resolve ABBA deadlock, A err=%d, B err=%d\n", 237 __func__, err, abba.result); 238 ret = -EINVAL; 239 } 240 } else { 241 if (err != -EDEADLK && abba.result != -EDEADLK) { 242 pr_err("%s: missed ABBA deadlock, A err=%d, B err=%d\n", 243 __func__, err, abba.result); 244 ret = -EINVAL; 245 } 246 } 247 return ret; 248} The issue here is that apparently abba.result is being used at lines 235, 237 and 241 without previous initialization. It seems to me that this is an issue, but I may be overlooking something. Can someone help me to spot where exactly abba.result is being initialized, if at all?You are only looking at half the code. Though the schedule/flush it is indirectly executing test_abba_work(). -Chris
I get it. Thanks for clarifying! -- Gustavo A. R. Silva
