Eric Lee / smarc-ti-linux-kernel

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Commit b4718c02f49ab5e1452353f0fae78beabe81467c

Authored by Dmitry Torokhov
Committed by Rafael J. Wysocki
1 parent 0fe30da2cb
Exists in ti-lsk-linux-4.1.y and in 10 other branches dlt-processor-sdk-linux-03.00.00.04, processor-sdk-linux-02.00.01, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04

PM / OPP: take RCU lock in dev_pm_opp_get_opp_count 

A lot of callers are missing the fact that dev_pm_opp_get_opp_count
needs to be called under RCU lock. Given that RCU locks can safely be
nested, instead of providing *_locked() API, let's take RCU lock inside
dev_pm_opp_get_opp_count() and leave callers as is.

Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Showing 1 changed file with 8 additions and 7 deletions Side-by-side Diff

drivers/base/power/opp.c
Diff comments   View file @ b4718c0
... ... @@ -216,9 +216,7 @@
216 216 * This function returns the number of available opps if there are any,
217 217 * else returns 0 if none or the corresponding error value.
218 218 *
219   - * Locking: This function must be called under rcu_read_lock(). This function
220   - * internally references two RCU protected structures: device_opp and opp which
221   - * are safe as long as we are under a common RCU locked section.
  219 + * Locking: This function takes rcu_read_lock().
222 220 */
223 221 int dev_pm_opp_get_opp_count(struct device *dev)
224 222 {
225 223  
... ... @@ -226,13 +224,14 @@
226 224 struct dev_pm_opp *temp_opp;
227 225 int count = 0;
228 226  
229   - opp_rcu_lockdep_assert();
  227 + rcu_read_lock();
230 228  
231 229 dev_opp = find_device_opp(dev);
232 230 if (IS_ERR(dev_opp)) {
233   - int r = PTR_ERR(dev_opp);
234   - dev_err(dev, "%s: device OPP not found (%d)\n", __func__, r);
235   - return r;
  231 + count = PTR_ERR(dev_opp);
  232 + dev_err(dev, "%s: device OPP not found (%d)\n",
  233 + __func__, count);
  234 + goto out_unlock;
236 235 }
237 236  
238 237 list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
... ... @@ -240,6 +239,8 @@
240 239 count++;
241 240 }
242 241  
  242 +out_unlock:
  243 + rcu_read_unlock();
243 244 return count;
244 245 }
245 246 EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_count);