source: trunk/server/common/patches/openafs-afs_conn-overcounts.patch @ 2658

Last change on this file since 2658 was 2649, checked in by andersk, 9 years ago
openafs: Fix some afs_conn overcounts Patch from http://gerrit.openafs.org/11464 .
File size: 2.5 KB

  • src/afs/afs_bypasscache.c 

    From 368fff3b2fef5b559ed6da016e1e9f0413b55552 Mon Sep 17 00:00:00 2001
From: Andrew Deason <adeason@sinenomine.net>
Date: Sun, 14 Sep 2014 14:10:11 -0500
Subject: [PATCH] afs: Fix some afs_conn overcounts

The usual pattern of using afs_Conn looks like this:

  do {
      tc = afs_Conn(...);
      if (tc) {
          code = /* ... */
      } else {
          code = -1;
      }
  } while (afs_Analyze(...));

The afs_Analyze call, amongst other things, puts back the reference to
the connection obtained from afs_Conn. If anything inside the do/while
block exits that block without calling afs_Analyze or afs_PutConn, we
will leak a reference to the conn.

A few places currently do this, by jumping out of the loop with
'goto's. Specifically, in afs_dcache.c and afs_bypasscache.c. These
locations currently leak references to our connection object (and to
the underlying Rx connection object), which can cause problems over
time. Specifically, this can cause a panic when the refcount overflows
and becomes negative, causing a panic message that looks like:

  afs_PutConn: refcount imbalance 0xd34db33f -32768

To avoid this, make sure we afs_PutConn in these cases where we 'goto'
out of the afs_Conn/afs_Analyze loop. Perhaps ideally we should cause
afs_Analyze itself to be called in these situations, but for now just
fix the problem with the least amount of impact possible.

FIXES 131885

Change-Id: I3a52f8ccef24f01d04c02db0a4b711405360e323
---
 src/afs/afs_bypasscache.c | 1 +
 src/afs/afs_dcache.c      | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/src/afs/afs_bypasscache.c b/src/afs/afs_bypasscache.c
index 744feb2..8fc6009 100644
    a b afs_PrefetchNoCache(struct vcache *avc, 
    637637            } else {
    638638                afs_warn("BYPASS: StartRXAFS_FetchData failed: %d\n", code);
    639639                unlock_and_release_pages(auio);
     640                afs_PutConn(tc, rxconn, SHARED_LOCK);
    640641                goto done;
    641642            }
    642643            if (code == 0) {

  • src/afs/afs_dcache.c 

    diff --git a/src/afs/afs_dcache.c b/src/afs/afs_dcache.c
index dc1e039..a156e22 100644
    a b afs_GetDCache(struct vcache *avc, afs_size_t abyte, 
    23992399                        afs_PutDCache(tdc);
    24002400                        tdc = 0;
    24012401                        ReleaseReadLock(&avc->lock);
     2402
     2403                        if (tc) {
     2404                            /* If we have a connection, we must put it back,
     2405                             * since afs_Analyze will not be called here. */
     2406                            afs_PutConn(tc, rxconn, SHARED_LOCK);
     2407                        }
     2408
    24022409                        slowPass = 1;
    24032410                        goto RetryGetDCache;
    24042411                    }
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