From: Andrew Deason <adeason@sinenomine.net>
Date: Mon, 22 Feb 2010 17:56:07 +0000 (-0600)
Subject: Prevent deadlock if fs_stateSave panics
X-Git-Tag: openafs-devel-1_5_73~149
X-Git-Url: https://git.michaelhowe.org/gitweb/?a=commitdiff_plain;h=1e744d5e56106093924869924fffde3a9093d140;p=packages%2Fo%2Fopenafs.git

Prevent deadlock if fs_stateSave panics

fs_stateSave can call ShutDownAndCore(PANIC) if it detects host list
corruption. Right now this will deadlock the shutdown thread, since
we're still holding a read lock on the FS state when we do so, and
ShutDownAndCore will attempt to acquire a write lock. Do two things to
make this a bit better:

 -- Unlock the FS state before calling fs_stateSave, sine we're no
 longer looking at the FS state (the 'state' in fs_stateSave refers to
 the host list and callback lists, not the state locked by
 FS_STATE_*LOCK)

 -- If ShutDownAndCore detects that it was called inside of
 ShutDownAndCore, skip shutting down the volume and host packages, since
 they have already been shut down

Change-Id: I24a994ff85a6d866a5800b777c0cf5ab2ba466e4
Reviewed-on: http://gerrit.openafs.org/1362
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
---

diff --git a/src/viced/viced.c b/src/viced/viced.c
index 4874a6fa5..1cb55848f 100644
--- a/src/viced/viced.c
+++ b/src/viced/viced.c
@@ -802,6 +802,15 @@ ShutDownAndCore(int dopanic)
 
 #ifdef AFS_DEMAND_ATTACH_FS
     FS_STATE_WRLOCK;
+    if (fs_state.mode == FS_MODE_SHUTDOWN) {
+	/* it is possible for at least fs_stateSave() (called below) to call
+	 * ShutDownAndCore if there's host list corruption; prevent
+	 * deinitializing some stuff twice */
+	ViceLog(0, ("ShutDownAndCore called during shutdown? Skipping volume "
+	            "and host package shutdown\n"));
+	FS_STATE_UNLOCK;
+	goto done_vol_host;
+    }
     fs_state.mode = FS_MODE_SHUTDOWN;
     FS_STATE_UNLOCK;
 #endif
@@ -847,11 +856,14 @@ ShutDownAndCore(int dopanic)
 		FS_UNLOCK;
 		FS_STATE_RDLOCK;
 	    }
+	    FS_STATE_UNLOCK;
 
 	    /* ok. it should now be fairly safe. let's do the state dump */
 	    fs_stateSave();
 	}
     }
+ done_vol_host:
+
 #endif /* AFS_DEMAND_ATTACH_FS */
 
     if (debugFile) {