From cb99519f776c33703e571aa2976250b203f15f06 Mon Sep 17 00:00:00 2001
From: Derrick Brashear <shadow@dementia.org>
Date: Tue, 13 Nov 2001 17:24:05 +0000
Subject: [PATCH] hold-afs-xcell-lock-during-setserverprefs-20011113

afs_RemoveCellEntry holds afs_xcell; setserverprefs modified the same
structure but did not which was problematic if something changed out from under
it
---
 src/afs/afs.h        |  1 +
 src/afs/afs_cell.c   | 26 ++++++++++++++++++++++----
 src/afs/afs_pioctl.c | 36 +++++++++++++++++++-----------------
 3 files changed, 42 insertions(+), 21 deletions(-)

diff --git a/src/afs/afs.h b/src/afs/afs.h
index 86a999688a..4656f9db53 100644
--- a/src/afs/afs.h
+++ b/src/afs/afs.h
@@ -968,6 +968,7 @@ extern struct brequest afs_brs[NBRS];		/* request structures */
 #define	FVHash(acell,avol)  (((avol)+(acell)) & (NFENTRIES-1))
 
 extern struct cell	    *afs_GetCell();
+extern struct cell	    *afs_GetCellNoLock();
 extern struct cell	    *afs_GetCellByName();
 extern struct cell	    *afs_GetCellByName2();
 extern struct cell	    *afs_GetCellByIndex();
diff --git a/src/afs/afs_cell.c b/src/afs/afs_cell.c
index 7416249d9f..1061d3d6a6 100644
--- a/src/afs/afs_cell.c
+++ b/src/afs/afs_cell.c
@@ -347,28 +347,46 @@ struct cell *afs_GetCellByName(acellName, locktype)
 
 } /*afs_GetCellByName*/
 
-
 struct cell *afs_GetCell(acell, locktype)
     register afs_int32 acell;
     afs_int32 locktype;
+{
+    return afs_GetCellInternal(acell, locktype, 1);
+}
+
+/* This is only to be called if the caller is already holding afs_xcell */
+struct cell *afs_GetCellNoLock(acell, locktype)
+    register afs_int32 acell;
+    afs_int32 locktype;
+{
+    return afs_GetCellInternal(acell, locktype, 0);
+}
+
+static struct cell *afs_GetCellInternal(acell, locktype, holdxcell)
+    register afs_int32 acell;
+    afs_int32 locktype;
+    int holdxcell;
 {
     register struct cell *tc;
     register struct afs_q *cq, *tq;
 
     AFS_STATCNT(afs_GetCell);
     if (acell == 1 && afs_rootcell) return afs_rootcell;
-    ObtainWriteLock(&afs_xcell,101);
+    if (holdxcell)
+	ObtainWriteLock(&afs_xcell,101);
     for (cq = CellLRU.next; cq != &CellLRU; cq = tq) {
 	tc = QTOC(cq); tq = QNext(cq);
 	if (tc->cell == acell) {
 	    QRemove(&tc->lruq);
 	    QAdd(&CellLRU, &tc->lruq);
-	    ReleaseWriteLock(&afs_xcell);
+	    if (holdxcell)
+		ReleaseWriteLock(&afs_xcell);
 	    afs_RefreshCell(tc);
 	    return tc;
 	}
     }
-    ReleaseWriteLock(&afs_xcell);
+    if (holdxcell)
+	ReleaseWriteLock(&afs_xcell);
     return (struct cell *) 0;
 
 } /*afs_GetCell*/
diff --git a/src/afs/afs_pioctl.c b/src/afs/afs_pioctl.c
index ae55c75b86..ab2fe28938 100644
--- a/src/afs/afs_pioctl.c
+++ b/src/afs/afs_pioctl.c
@@ -2941,27 +2941,29 @@ static void ReSortCells(s,l, vlonly)
   register int  k;
 
   if (vlonly) {
-     struct cell *tcell;
-     for(k=0;k<s;k++) {
-        tcell = afs_GetCell(l[k], WRITE_LOCK);
-	if (!tcell) continue;
-	afs_SortServers(tcell->cellHosts, MAXCELLHOSTS);
-	afs_PutCell(tcell, WRITE_LOCK);
-     }
-     return;
+      struct cell *tcell;
+      ObtainWriteLock(&afs_xcell,300);
+      for(k=0;k<s;k++) {
+	  tcell = afs_GetCellNoLock(l[k], WRITE_LOCK);
+	  if (!tcell) continue;
+	  afs_SortServers(tcell->cellHosts, MAXCELLHOSTS);
+	  afs_PutCell(tcell, WRITE_LOCK);
+      }
+      ReleaseWriteLock(&afs_xcell);
+      return;
   }
 
   ObtainReadLock(&afs_xvolume);
   for (i= 0; i< NVOLS; i++) {
-     for (j=afs_volumes[i];j;j=j->next) {
-        for (k=0;k<s;k++)
-	   if (j->cell == l[k]) {
-	      ObtainWriteLock(&j->lock,233);
-	      afs_SortServers(j->serverHost, MAXHOSTS);
-	      ReleaseWriteLock(&j->lock);
-	      break; 
-	   }
-     }
+      for (j=afs_volumes[i];j;j=j->next) {
+	  for (k=0;k<s;k++)
+	      if (j->cell == l[k]) {
+		  ObtainWriteLock(&j->lock,233);
+		  afs_SortServers(j->serverHost, MAXHOSTS);
+		  ReleaseWriteLock(&j->lock);
+		  break; 
+	      }
+      }
   }
   ReleaseReadLock(&afs_xvolume);
 }