Doug / smarc-fsl-linux-kernel

Download as
Browse Code ยป

Commit f96e9232e04856c781d4f71923a46dd3f7b429fa

Authored by Paul E. McKenney
Committed by Ingo Molnar
1 parent 7284ce6c9f

rcu: Adjust force_quiescent_state() locking, step 1 

This causes rnp->lock to be held on entry to
force_quiescent_state()'s switch statement.  This is a first
step towards prohibiting starting grace periods while
force_quiescent_state() is executing, which will reduce the
number and complexity of races that force_quiescent_state() is
involved in.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <12626465501455-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Showing 1 changed file with 18 additions and 9 deletions Side-by-side Diff

... ... @@ -1204,7 +1204,7 @@
1204 1204 }
1205 1205 if (relaxed &&
1206 1206 (long)(rsp->jiffies_force_qs - jiffies) >= 0)
1207   - goto unlock_ret; /* no emergency and done recently. */
  1207 + goto unlock_fqs_ret; /* no emergency and done recently. */
1208 1208 rsp->n_force_qs++;
1209 1209 spin_lock(&rnp->lock);
1210 1210 lastcomp = rsp->gpnum - 1;
1211 1211  
1212 1212  
1213 1213  
1214 1214  
1215 1215  
... ... @@ -1213,31 +1213,32 @@
1213 1213 if(!rcu_gp_in_progress(rsp)) {
1214 1214 rsp->n_force_qs_ngp++;
1215 1215 spin_unlock(&rnp->lock);
1216   - goto unlock_ret; /* no GP in progress, time updated. */
  1216 + goto unlock_fqs_ret; /* no GP in progress, time updated. */
1217 1217 }
1218   - spin_unlock(&rnp->lock);
1219 1218 switch (signaled) {
1220 1219 case RCU_GP_IDLE:
1221 1220 case RCU_GP_INIT:
1222 1221  
  1222 + spin_unlock(&rnp->lock);
1223 1223 break; /* grace period idle or initializing, ignore. */
1224 1224  
1225 1225 case RCU_SAVE_DYNTICK:
1226 1226  
  1227 + spin_unlock(&rnp->lock);
1227 1228 if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK)
1228 1229 break; /* So gcc recognizes the dead code. */
1229 1230  
1230 1231 /* Record dyntick-idle state. */
1231 1232 if (rcu_process_dyntick(rsp, lastcomp,
1232 1233 dyntick_save_progress_counter))
1233   - goto unlock_ret;
  1234 + goto unlock_fqs_ret;
  1235 + spin_lock(&rnp->lock);
1234 1236 /* fall into next case. */
1235 1237  
1236 1238 case RCU_SAVE_COMPLETED:
1237 1239  
1238 1240 /* Update state, record completion counter. */
1239 1241 forcenow = 0;
1240   - spin_lock(&rnp->lock);
1241 1242 if (lastcomp + 1 == rsp->gpnum &&
1242 1243 lastcomp == rsp->completed &&
1243 1244 rsp->signaled == signaled) {
1244 1245  
1245 1246  
1246 1247  
1247 1248  
1248 1249  
... ... @@ -1245,23 +1246,31 @@
1245 1246 rsp->completed_fqs = lastcomp;
1246 1247 forcenow = signaled == RCU_SAVE_COMPLETED;
1247 1248 }
1248   - spin_unlock(&rnp->lock);
1249   - if (!forcenow)
  1249 + if (!forcenow) {
  1250 + spin_unlock(&rnp->lock);
1250 1251 break;
  1252 + }
1251 1253 /* fall into next case. */
1252 1254  
1253 1255 case RCU_FORCE_QS:
1254 1256  
1255 1257 /* Check dyntick-idle state, send IPI to laggarts. */
  1258 + spin_unlock(&rnp->lock);
1256 1259 if (rcu_process_dyntick(rsp, rsp->completed_fqs,
1257 1260 rcu_implicit_dynticks_qs))
1258   - goto unlock_ret;
  1261 + goto unlock_fqs_ret;
1259 1262  
1260 1263 /* Leave state in case more forcing is required. */
1261 1264  
1262 1265 break;
  1266 +
  1267 + default:
  1268 +
  1269 + spin_unlock(&rnp->lock);
  1270 + WARN_ON_ONCE(1);
  1271 + break;
1263 1272 }
1264   -unlock_ret:
  1273 +unlock_fqs_ret:
1265 1274 spin_unlock_irqrestore(&rsp->fqslock, flags);
1266 1275 }
1267 1276