Changeset 28405 for trunk/psLib/src/imageops

Timestamp:

Jun 18, 2010, 2:25:38 PM (16 years ago)

Author:

Paul Price

Message:

Discovered a race condition in the threading process. The thread process was: psThreadJobAlloc, populate job with arguments, psThreadJobAddPending, psFree the job. This is not thread-safe, because we're decrementing the job's reference counter while the reference count is also being fiddled within the thread system (psThread.c; by pulling the job off the 'pending' queue and putting it on the 'done' queue). The reference count fiddling within the thread system was protected by a mutex, but the external free was not. Therefore, I'm pulling the free into the thread system so it can be protected (without the user having to worry about locks to do the simple case). This means that the user should no longer touch the job once he hands it over to the thread system (unless it's protected by calls to psThreadLock/psThreadUnlock, or it's on the other side of psThreadPoolWait from all the adds so that the threads aren't doing anything).

Location:

trunk/psLib/src/imageops

Files:

• psImageConvolve.c (modified) (7 diffs)
• psImageCovariance.c (modified) (2 diffs)

trunk/psLib/src/imageops/psImageConvolve.c

@@ -864 +864 @@
             PS_ARRAY_ADD_SCALAR(job->args, stop, PS_TYPE_S32);
             if (!psThreadJobAddPending(job)) {
-                psFree(job);
                 psFree(gaussNorm);
                 psFree(out);
                 return NULL;
             }
-            psFree(job);
         }
         if (!psThreadPoolWait(true)) {
@@ -1213 +1211 @@
                   if (!psThreadJobAddPending(job)) {
                       psError(PS_ERR_UNKNOWN, false, "Unable to smooth image");
-                      psFree(job);
                       psFree(calculation);
                       psFree(calcMask);
@@ -1219 +1216 @@
                       return false;
                   }
-                  psFree(job);
               }
               // wait here for the threaded jobs to finish (NOP if threading is not active)
@@ -1261 +1257 @@
                   if (!psThreadJobAddPending(job)) {
                       psError(PS_ERR_UNKNOWN, false, "Unable to smooth image");
-                      psFree(job);
                       psFree(calculation);
                       psFree(calcMask);
@@ -1267 +1262 @@
                       return false;
                   }
-                  psFree(job);
               }
 
@@ -1580 +1574 @@
             PS_ARRAY_ADD_SCALAR(job->args, 0x00, PS_TYPE_U8); // specify rows
             if (!psThreadJobAddPending(job)) {
-                psFree(job);
                 psFree(conv);
                 psFree(out);
                 return NULL;
             }
-            psFree(job);
         }
         if (!psThreadPoolWait(true)) {
@@ -1617 +1609 @@
             PS_ARRAY_ADD_SCALAR(job->args, 0xff, PS_TYPE_U8); // specify cols
             if (!psThreadJobAddPending(job)) {
-                psFree(job);
                 psFree(conv);
                 psFree(out);
                 return NULL;
             }
-            psFree(job);
         }
         if (!psThreadPoolWait(true)) {

trunk/psLib/src/imageops/psImageCovariance.c

@@ -169 +169 @@
                     return NULL;
                 }
-                psFree(job);
             } else {
                 out->kernel[y][x] = imageCovarianceCalculate(covar, kernel, x, y);
@@ -334 +333 @@
                     return NULL;
                 }
-                psFree(job);
             } else {
                 out->kernel[y][x] = imageCovarianceBin(covar, bin, binVal, x, y);