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* [Ocfs2-devel] About Mark's advice on bug 48
@ 2004-03-25  3:26 Sonic Zhang
  2004-03-25 13:10 ` Mark Fasheh
  0 siblings, 1 reply; 6+ messages in thread
From: Sonic Zhang @ 2004-03-25  3:26 UTC (permalink / raw)
  To: ocfs2-devel

Hi Mark,

    I change a little to your patch. I remove the signal prcess code, 
because kernel thread doesn't receive signals by default. This patch 
fixes the halt problem in thread ocfs_submit_thread(). But, there is 
another dead lock on osb->publish_lock in thread  ocfs_volume_thread() 
and routine ocfs_journal_set_unmounted(). I am tracking this problem now.

Following is the revised patch for journal.c
--------------------------------------------------------------
--- journal.c.old    2004-03-25 10:44:20.000000000 +0800
+++ journal.c    2004-03-25 10:57:53.000000000 +0800
@@ -1765,7 +1765,10 @@
                 LOG_TRACE_STR("FLUSH_EVENT: timed out");
                 break;
             case -EINTR:
-                finish = 1;
+                /* journal shutdown has asked me to do
+                 * one last commit cache and then exit */
+                if (journal->state == OCFS_JOURNAL_IN_SHUTDOWN)
+                    finish = 1;
                 LOG_TRACE_STR("FLUSH_EVENT: interrupted");
                 break;
             case 0:
@@ -1778,7 +1781,7 @@
 
         if ((OcfsGlobalCtxt.flags & OCFS_FLAG_SHUTDOWN_VOL_THREAD) ||
             (osb->osb_flags & OCFS_OSB_FLAGS_BEING_DISMOUNTED))
-            break;
+            finish = 1;
 
         //if (!osb->needs_flush && status != 0)
         //    continue;
@@ -1788,18 +1791,13 @@
 
         if (down_trylock(&osb->trans_lock) != 0) {
             LOG_TRACE_ARGS("commit thread: trylock failed, miss=%d\n", 
misses);
-            if (++misses < OCFS_COMMIT_MISS_MAX)
+            if (++misses < OCFS_COMMIT_MISS_MAX && finish == 0)
                 continue;
             LOG_TRACE_ARGS("commit thread: about to down\n");
             down(&osb->trans_lock);
             misses = 0;
         }
 
-        /* journal shutdown has asked me to do one last commit cache */
-        /* this commit cache will leave trans lock held! */
-        if (journal->state == OCFS_JOURNAL_IN_SHUTDOWN)
-            finish = 1;
-
         status = ocfs_commit_cache (osb, false);
         if (status < 0)
             LOG_ERROR_STATUS(status);

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [Ocfs2-devel] About Mark's advice on bug 48
@ 2004-03-26  1:26 Sonic Zhang
  2004-03-26  2:27 ` Sonic Zhang
  2004-03-29 14:28 ` Mark Fasheh
  0 siblings, 2 replies; 6+ messages in thread
From: Sonic Zhang @ 2004-03-26  1:26 UTC (permalink / raw)
  To: ocfs2-devel

Hi Mark,

Finally, I found the second halt is caused by starvation when routine 
ocfs_joutnal_set_unmounted() acquiring the lock osb->publish_lock. In 
thread ocfs_volume_thread(), the delta jiffies to sleep between up() and 
down() in schedule_timeout() is too short. Routine 
ocfs_joutnal_set_unmounted() has no chance to check if lock 
osb->publish_lock is released  between it is releases and reacquired by 
thread ocfs_volume_thread. So routine ocfs_journal_set_unmounted() 
always waits in loop. After I change the delta jiffies from 50 to 500, 
kernel 2.6 won't halt when it reboots after  a OCFS volume is mounted.

I also add a line to release the lock in a branch to  symbol "finally". 
 This may remove latent dead lock. In addition, I clear the reference 
point OcfsIpcCtxt.task before thread ocfs_recv_thread() exits. This 
prevents invalid access to the task structure in routine 
ocfs_dismount_volume() when rebooting.

Here is my patch to file nm.c.
-------------------------------------------------------------------
--- ocfs2.old/src/nm.c.old    2004-03-26 15:21:32.000000000 +0800
+++ ocfs2/src/nm.c    2004-03-26 15:21:06.000000000 +0800
@@ -119,6 +119,8 @@
         OcfsIpcCtxt.recv_sock = NULL;
     }
 
+    OcfsIpcCtxt.task = NULL;
+   
     /* signal main thread of ipcdlm's exit */
     complete (&(OcfsIpcCtxt.complete));
 
@@ -227,6 +229,12 @@
 //#define OCFS_BH_SEM_PRUNE_LIMIT   60   // prune everything each 30 
seconds
 #define OCFS_BH_SEM_PRUNE_LIMIT   60000  // 8 hours :)
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
+#define OCFS_SCHEDULE_TIMEOUT_JIFFIES    500
+#else
+#define OCFS_SCHEDULE_TIMEOUT_JIFFIES    50
+#endif
+
 /*
  * ocfs_volume_thread()
  *
@@ -409,6 +417,7 @@
                 OCFS_BH_PUT_DATA(bh);
                 status = ocfs_write_bh(osb, bh, 0, NULL);
                 if (status < 0) {
+                    up(&(osb->publish_lock));
                     LOG_ERROR_STATUS (status);
                     goto finally;
                 }
@@ -425,7 +434,7 @@
                 goto finally;
             }
         }
-        osb->hbt = 50 + jiffies;
+        osb->hbt = OCFS_SCHEDULE_TIMEOUT_JIFFIES + jiffies;
 
 finally:
         status = 0;
@@ -435,7 +444,7 @@
             break;
         j = jiffies;
         if (time_after (j, (unsigned long) (osb->hbt))) {
-            osb->hbt = 50 + j;
+            osb->hbt = OCFS_SCHEDULE_TIMEOUT_JIFFIES + j;
         }
         set_current_state (TASK_INTERRUPTIBLE);
         schedule_timeout (osb->hbt - j);

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2004-03-29 14:28 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2004-03-25  3:26 [Ocfs2-devel] About Mark's advice on bug 48 Sonic Zhang
2004-03-25 13:10 ` Mark Fasheh
  -- strict thread matches above, loose matches on Subject: below --
2004-03-26  1:26 Sonic Zhang
2004-03-26  2:27 ` Sonic Zhang
2004-03-29 14:13   ` Mark Fasheh
2004-03-29 14:28 ` Mark Fasheh

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