[hurd] 01/02: Fix a spurious hashtable removal

[Samuel Thibault]

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sthibault pushed a commit to branch master
in repository hurd.

commit 4082a842d743fba88291568cd4a846647b5c871f
Author: Samuel Thibault <address@hidden>
Date:   Sat Jan 6 00:16:43 2018 +0000

    Fix a spurious hashtable removal
---
 debian/changelog                         |  1 +
 debian/patches/get-identity_weakref.diff | 36 ++++++++++++++++++++++++++++++++
 debian/patches/series                    |  1 +
 3 files changed, 38 insertions(+)

diff --git a/debian/changelog b/debian/changelog
index 276a432..98de37b 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -2,6 +2,7 @@ hurd (1:0.9.git20171119-4) UNRELEASED; urgency=medium
 
   * patches/get-identity_hash.diff: Fix inode hashing for FS with inode
     numbers bigger than 4 billion.
+  * patches/get-identity_weakref.diff: Fix a spurious hashtable removal.
 
  -- Samuel Thibault <address@hidden>  Fri, 05 Jan 2018 23:55:59 +0000
 
diff --git a/debian/patches/get-identity_weakref.diff 
b/debian/patches/get-identity_weakref.diff
new file mode 100644
index 0000000..4752e72
--- /dev/null
+++ b/debian/patches/get-identity_weakref.diff
@@ -0,0 +1,36 @@
+commit a7c7e4c642aa284cb57a855ea94bab90cc2dae3e
+Author: Samuel Thibault <address@hidden>
+Date:   Sat Jan 6 01:13:02 2018 +0100
+
+    libfshelp/get-identity.c: Avoid spurious ihash removal
+    
+    Reported by Brent W. Baccala.
+    
+    While some thread has converted a hardref to a weakref and tries to release
+    the hash weakref, another thread might reacquire a hardref, and then 
convert
+    it to a weakref and try to release it. We thus have to make sure that we
+    really have the last weakref before removing from the hash.
+    
+    * libfshelp/get-identity.c (id_clean): Also check that there are only
+    two weak refs left.
+
+diff --git a/libfshelp/get-identity.c b/libfshelp/get-identity.c
+index f88e0f82..96de55a8 100644
+--- a/libfshelp/get-identity.c
++++ b/libfshelp/get-identity.c
+@@ -69,10 +69,13 @@ static void
+ id_clean (void *cookie)
+ {
+   struct idspec *i = cookie;
++  struct references result;
+   pthread_mutex_lock (&idlock);
+-  if (refcounts_hard_references(&i->pi.refcounts) == 0)
++  refcounts_references (&i->pi.refcounts, &result);
++  if (result.hard == 0 && result.weak == 2)
+     {
+-      /* Nobody got a send right in between, we can remove from the hash.  */
++      /* Nobody got a send right in between and we have the last weak 
reference
++         in addition to our caller's, so we can remove from the hash. */
+       hurd_ihash_locp_remove (&idhash, i->id_hashloc);
+       ports_port_deref_weak (&i->pi);
+     }
diff --git a/debian/patches/series b/debian/patches/series
index a130fb5..12b415d 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -32,3 +32,4 @@ exec_set_exe.patch
 pie-core
 hash-weakref
 get-identity_hash.diff
+get-identity_weakref.diff

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