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-rw-r--r--debian/patches/0008-libports-lock-less-reference-counting-for-port_info-.patch345
1 files changed, 345 insertions, 0 deletions
diff --git a/debian/patches/0008-libports-lock-less-reference-counting-for-port_info-.patch b/debian/patches/0008-libports-lock-less-reference-counting-for-port_info-.patch
new file mode 100644
index 00000000..c4b63d69
--- /dev/null
+++ b/debian/patches/0008-libports-lock-less-reference-counting-for-port_info-.patch
@@ -0,0 +1,345 @@
+From 033ef517de7f127bb5c592d4eb70e6e91093df6a Mon Sep 17 00:00:00 2001
+From: Justus Winter <4winter@informatik.uni-hamburg.de>
+Date: Sat, 3 May 2014 01:02:35 +0200
+Subject: [PATCH 08/14] libports: lock-less reference counting for port_info
+ objects
+
+* libports/ports.h (struct port_info): Use the new type.
+* libports/lookup-port.c: No need to lock _ports_lock anymore.
+* libports/bucket-iterate.c: Likewise.
+* libports/complete-deallocate.c: Check if someone reacquired a
+reference through a hash table lookup.
+* libports/create-internal.c: Use the new reference counting primitives.
+* libports/get-right.c: Likewise.
+* libports/import-port.c: Likewise.
+* libports/port-deref-weak.c: Likewise.
+* libports/port-deref.c: Likewise.
+* libports/port-ref-weak.c: Likewise.
+* libports/port-ref.c: Likewise.
+* libports/reallocate-from-external.c: Likewise.
+* libports/transfer-right.c: Likewise.
+* utils/rpctrace.c: Likewise.
+---
+ libports/bucket-iterate.c | 4 +---
+ libports/complete-deallocate.c | 14 ++++++++++++++
+ libports/create-internal.c | 3 +--
+ libports/get-right.c | 2 +-
+ libports/import-port.c | 3 +--
+ libports/lookup-port.c | 6 ++----
+ libports/port-deref-weak.c | 10 +++-------
+ libports/port-deref.c | 34 ++++++++++++++++------------------
+ libports/port-ref-weak.c | 8 +++-----
+ libports/port-ref.c | 8 +++-----
+ libports/ports.h | 4 ++--
+ libports/reallocate-from-external.c | 2 +-
+ libports/transfer-right.c | 2 +-
+ utils/rpctrace.c | 10 ++++++++--
+ 14 files changed, 57 insertions(+), 53 deletions(-)
+
+diff --git a/libports/bucket-iterate.c b/libports/bucket-iterate.c
+index 06d8f7d..8a28827 100644
+--- a/libports/bucket-iterate.c
++++ b/libports/bucket-iterate.c
+@@ -35,7 +35,6 @@ _ports_bucket_class_iterate (struct hurd_ihash *ht,
+ size_t i, n, nr_items;
+ error_t err;
+
+- pthread_mutex_lock (&_ports_lock);
+ pthread_mutex_lock (&_ports_htable_lock);
+
+ if (ht->nr_items == 0)
+@@ -59,13 +58,12 @@ _ports_bucket_class_iterate (struct hurd_ihash *ht,
+
+ if (class == 0 || pi->class == class)
+ {
+- pi->refcnt++;
++ refcounts_ref (&pi->refcounts, NULL);
+ p[n] = pi;
+ n++;
+ }
+ }
+ pthread_mutex_unlock (&_ports_htable_lock);
+- pthread_mutex_unlock (&_ports_lock);
+
+ if (n == 0)
+ {
+diff --git a/libports/complete-deallocate.c b/libports/complete-deallocate.c
+index 50548ec..a239957 100644
+--- a/libports/complete-deallocate.c
++++ b/libports/complete-deallocate.c
+@@ -29,15 +29,29 @@ _ports_complete_deallocate (struct port_info *pi)
+
+ if (pi->port_right)
+ {
++ struct references result;
++
+ pthread_mutex_lock (&_ports_htable_lock);
++ refcounts_references (&pi->refcounts, &result);
++ if (result.hard > 0 || result.weak > 0)
++ {
++ /* A reference was reacquired through a hash table lookup.
++ It's fine, we didn't touch anything yet. */
++ pthread_mutex_unlock (&_ports_htable_lock);
++ return;
++ }
++
+ hurd_ihash_locp_remove (&_ports_htable, pi->ports_htable_entry);
+ hurd_ihash_locp_remove (&pi->bucket->htable, pi->hentry);
+ pthread_mutex_unlock (&_ports_htable_lock);
++
+ mach_port_mod_refs (mach_task_self (), pi->port_right,
+ MACH_PORT_RIGHT_RECEIVE, -1);
+ pi->port_right = MACH_PORT_NULL;
+ }
+
++ pthread_mutex_lock (&_ports_lock);
++
+ pi->bucket->count--;
+ pi->class->count--;
+
+diff --git a/libports/create-internal.c b/libports/create-internal.c
+index 2981e74..4f1e512 100644
+--- a/libports/create-internal.c
++++ b/libports/create-internal.c
+@@ -54,8 +54,7 @@ _ports_create_port_internal (struct port_class *class,
+ }
+
+ pi->class = class;
+- pi->refcnt = 1;
+- pi->weakrefcnt = 0;
++ refcounts_init (&pi->refcounts, 1, 0);
+ pi->cancel_threshold = 0;
+ pi->mscount = 0;
+ pi->flags = 0;
+diff --git a/libports/get-right.c b/libports/get-right.c
+index 89050c6..8681f46 100644
+--- a/libports/get-right.c
++++ b/libports/get-right.c
+@@ -41,7 +41,7 @@ ports_get_right (void *port)
+ if ((pi->flags & PORT_HAS_SENDRIGHTS) == 0)
+ {
+ pi->flags |= PORT_HAS_SENDRIGHTS;
+- pi->refcnt++;
++ refcounts_ref (&pi->refcounts, NULL);
+ err = mach_port_request_notification (mach_task_self (),
+ pi->port_right,
+ MACH_NOTIFY_NO_SENDERS,
+diff --git a/libports/import-port.c b/libports/import-port.c
+index 91afaa7..8601d0e 100644
+--- a/libports/import-port.c
++++ b/libports/import-port.c
+@@ -48,8 +48,7 @@ ports_import_port (struct port_class *class, struct port_bucket *bucket,
+ return ENOMEM;
+
+ pi->class = class;
+- pi->refcnt = 1 + !!stat.mps_srights;
+- pi->weakrefcnt = 0;
++ refcounts_init (&pi->refcounts, 1 + !!stat.mps_srights, 0);
+ pi->cancel_threshold = 0;
+ pi->mscount = stat.mps_mscount;
+ pi->flags = stat.mps_srights ? PORT_HAS_SENDRIGHTS : 0;
+diff --git a/libports/lookup-port.c b/libports/lookup-port.c
+index fbb13ef..1bf012f 100644
+--- a/libports/lookup-port.c
++++ b/libports/lookup-port.c
+@@ -28,7 +28,6 @@ ports_lookup_port (struct port_bucket *bucket,
+ {
+ struct port_info *pi;
+
+- pthread_mutex_lock (&_ports_lock);
+ pthread_mutex_lock (&_ports_htable_lock);
+
+ pi = hurd_ihash_find (&_ports_htable, port);
+@@ -38,10 +37,9 @@ ports_lookup_port (struct port_bucket *bucket,
+ pi = 0;
+
+ if (pi)
+- pi->refcnt++;
++ ports_port_ref (pi);
+
+ pthread_mutex_unlock (&_ports_htable_lock);
+- pthread_mutex_unlock (&_ports_lock);
+-
++
+ return pi;
+ }
+diff --git a/libports/port-deref-weak.c b/libports/port-deref-weak.c
+index beb4842..8432660 100644
+--- a/libports/port-deref-weak.c
++++ b/libports/port-deref-weak.c
+@@ -25,12 +25,8 @@ void
+ ports_port_deref_weak (void *portstruct)
+ {
+ struct port_info *pi = portstruct;
+-
+- pthread_mutex_lock (&_ports_lock);
+- assert (pi->weakrefcnt);
+- pi->weakrefcnt--;
+- if (pi->refcnt == 0 && pi->weakrefcnt == 0)
++ struct references result;
++ refcounts_deref_weak (&pi->refcounts, &result);
++ if (result.hard == 0 && result.weak == 0)
+ _ports_complete_deallocate (pi);
+- else
+- pthread_mutex_unlock (&_ports_lock);
+ }
+diff --git a/libports/port-deref.c b/libports/port-deref.c
+index cf9b238..b97dd13 100644
+--- a/libports/port-deref.c
++++ b/libports/port-deref.c
+@@ -25,26 +25,24 @@ void
+ ports_port_deref (void *portstruct)
+ {
+ struct port_info *pi = portstruct;
+- int trieddroppingweakrefs = 0;
+-
+- retry:
+-
+- pthread_mutex_lock (&_ports_lock);
+-
+- if (pi->refcnt == 1 && pi->weakrefcnt
+- && pi->class->dropweak_routine && !trieddroppingweakrefs)
++ struct references result;
++
++ if (pi->class->dropweak_routine)
+ {
+- pthread_mutex_unlock (&_ports_lock);
+- (*pi->class->dropweak_routine) (pi);
+- trieddroppingweakrefs = 1;
+- goto retry;
++ /* If we need to call the dropweak routine, we need to hold one
++ reference while doing so. We use a weak reference for this
++ purpose, which we acquire by demoting our hard reference to a
++ weak one. */
++ refcounts_demote (&pi->refcounts, &result);
++
++ if (result.hard == 0 && result.weak > 1)
++ (*pi->class->dropweak_routine) (pi);
++
++ refcounts_deref_weak (&pi->refcounts, &result);
+ }
+-
+- assert (pi->refcnt);
++ else
++ refcounts_deref (&pi->refcounts, &result);
+
+- pi->refcnt--;
+- if (pi->refcnt == 0 && pi->weakrefcnt == 0)
++ if (result.hard == 0 && result.weak == 0)
+ _ports_complete_deallocate (pi);
+- else
+- pthread_mutex_unlock (&_ports_lock);
+ }
+diff --git a/libports/port-ref-weak.c b/libports/port-ref-weak.c
+index c7d3c69..e4b7fc8 100644
+--- a/libports/port-ref-weak.c
++++ b/libports/port-ref-weak.c
+@@ -25,9 +25,7 @@ void
+ ports_port_ref_weak (void *portstruct)
+ {
+ struct port_info *pi = portstruct;
+-
+- pthread_mutex_lock (&_ports_lock);
+- assert (pi->refcnt || pi->weakrefcnt);
+- pi->weakrefcnt++;
+- pthread_mutex_unlock (&_ports_lock);
++ struct references result;
++ refcounts_ref_weak (&pi->refcounts, &result);
++ assert (result.hard > 0 || result.weak > 1);
+ }
+diff --git a/libports/port-ref.c b/libports/port-ref.c
+index 92b7118..761c50f 100644
+--- a/libports/port-ref.c
++++ b/libports/port-ref.c
+@@ -25,9 +25,7 @@ void
+ ports_port_ref (void *portstruct)
+ {
+ struct port_info *pi = portstruct;
+-
+- pthread_mutex_lock (&_ports_lock);
+- assert (pi->refcnt || pi->weakrefcnt);
+- pi->refcnt++;
+- pthread_mutex_unlock (&_ports_lock);
++ struct references result;
++ refcounts_ref (&pi->refcounts, &result);
++ assert (result.hard > 1 || result.weak > 0);
+ }
+diff --git a/libports/ports.h b/libports/ports.h
+index c29d78a..3439443 100644
+--- a/libports/ports.h
++++ b/libports/ports.h
+@@ -27,6 +27,7 @@
+ #include <hurd/ihash.h>
+ #include <mach/notify.h>
+ #include <pthread.h>
++#include <refcount.h>
+
+ /* These are global values for common flags used in the various structures.
+ Not all of these are meaningful in all flag fields. */
+@@ -39,8 +40,7 @@
+ struct port_info
+ {
+ struct port_class *class;
+- int refcnt;
+- int weakrefcnt;
++ refcounts_t refcounts;
+ mach_port_mscount_t mscount;
+ mach_msg_seqno_t cancel_threshold;
+ int flags;
+diff --git a/libports/reallocate-from-external.c b/libports/reallocate-from-external.c
+index 678b5d9..a912725 100644
+--- a/libports/reallocate-from-external.c
++++ b/libports/reallocate-from-external.c
+@@ -56,7 +56,7 @@ ports_reallocate_from_external (void *portstruct, mach_port_t receive)
+ else if (((pi->flags & PORT_HAS_SENDRIGHTS) == 0) && stat.mps_srights)
+ {
+ pi->flags |= PORT_HAS_SENDRIGHTS;
+- pi->refcnt++;
++ refcounts_ref (&pi->refcounts, NULL);
+ }
+
+ pi->port_right = receive;
+diff --git a/libports/transfer-right.c b/libports/transfer-right.c
+index 3f23d93..0e898ba 100644
+--- a/libports/transfer-right.c
++++ b/libports/transfer-right.c
+@@ -72,7 +72,7 @@ ports_transfer_right (void *tostruct,
+ else if (((topi->flags & PORT_HAS_SENDRIGHTS) == 0) && hassendrights)
+ {
+ topi->flags |= PORT_HAS_SENDRIGHTS;
+- topi->refcnt++;
++ refcounts_ref (&topi->refcounts, NULL);
+ }
+ }
+
+diff --git a/utils/rpctrace.c b/utils/rpctrace.c
+index fc913e3..b11fea4 100644
+--- a/utils/rpctrace.c
++++ b/utils/rpctrace.c
+@@ -431,7 +431,9 @@ destroy_receiver_info (struct receiver_info *info)
+ while (send_wrapper)
+ {
+ struct sender_info *next = send_wrapper->next;
+- assert (TRACED_INFO (send_wrapper)->pi.refcnt == 1);
++ assert (
++ refcounts_hard_references (&TRACED_INFO (send_wrapper)->pi.refcounts)
++ == 1);
+ /* Reset the receive_right of the send wrapper in advance to avoid
+ * destroy_receiver_info is called when the port info is destroyed. */
+ send_wrapper->receive_right = NULL;
+@@ -848,7 +850,11 @@ rewrite_right (mach_port_t *right, mach_msg_type_name_t *type,
+ hurd_ihash_locp_remove (&traced_names, receiver_info->locp);
+
+ send_wrapper2 = get_send_wrapper (receiver_info, dest, &rr);
+- assert (TRACED_INFO (send_wrapper2)->pi.refcnt == 1);
++ assert (
++ refcounts_hard_references (
++ &TRACED_INFO (send_wrapper2)->pi.refcounts)
++ == 1);
++
+ name = TRACED_INFO (send_wrapper2)->name;
+ TRACED_INFO (send_wrapper2)->name = NULL;
+ /* send_wrapper2 isn't destroyed normally, so we need to unlink
+--
+2.0.0.rc2
+