add patch series

2 files changed, 81 insertions, 0 deletions

diff --git a/debian/patches/0001-libports-avoid-acquiring-global-lock-in-message-disp.patch b/debian/patches/0001-libports-avoid-acquiring-global-lock-in-message-disp.patch
new file mode 100644
index 00000000..e2586f40
--- /dev/null
+++ b/debian/patches/0001-libports-avoid-acquiring-global-lock-in-message-disp.patch
@@ -0,0 +1,80 @@
+From 9e94fffba8ffbc9af4a6ceb75a78d2dab2da5682 Mon Sep 17 00:00:00 2001
+From: Justus Winter <4winter@informatik.uni-hamburg.de>
+Date: Mon, 15 Dec 2014 11:53:26 +0100
+Subject: [PATCH hurd] libports: avoid acquiring global lock in message
+ dispatch
+
+* libports/interrupt-operation.c (ports_S_interrupt_operation): Update
+`cancel_threshold' using atomic operations.
+* libports/manage-multithread.c (internal_demuxer): Avoid taking the lock.
+* libports/ports.h (struct port_info): Mention that one needs atomic
+operations to access `cancel_threshold'.
+---
+ libports/interrupt-operation.c | 14 ++++++++++----
+ libports/manage-multithread.c  |  8 +++++---
+ libports/ports.h               |  2 +-
+ 3 files changed, 16 insertions(+), 8 deletions(-)
+
+diff --git a/libports/interrupt-operation.c b/libports/interrupt-operation.c
+index 943bd4f..5d4b0b7 100644
+--- a/libports/interrupt-operation.c
++++ b/libports/interrupt-operation.c
+@@ -27,12 +27,18 @@ kern_return_t
+ ports_S_interrupt_operation (struct port_info *pi,
+ 			     mach_port_seqno_t seqno)
+ {
++  mach_port_seqno_t old;
++
+   if (!pi)
+     return EOPNOTSUPP;
+-  pthread_mutex_lock (&_ports_lock);
+-  if (pi->cancel_threshold < seqno)
+-    pi->cancel_threshold = seqno;
+-  pthread_mutex_unlock (&_ports_lock);
++
++ retry:
++  old = __atomic_load_n (&pi->cancel_threshold, __ATOMIC_SEQ_CST);
++  if (old < seqno
++      && ! __atomic_compare_exchange_n (&pi->cancel_threshold, &old, seqno,
++					0, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST))
++	goto retry;
++
+   ports_interrupt_rpcs (pi);
+   return 0;
+ }
+diff --git a/libports/manage-multithread.c b/libports/manage-multithread.c
+index 2067cba..7d2e126 100644
+--- a/libports/manage-multithread.c
++++ b/libports/manage-multithread.c
+@@ -173,10 +173,12 @@ ports_manage_port_operations_multithread (struct port_bucket *bucket,
+ 	    }
+ 	  else
+ 	    {
+-	      pthread_mutex_lock (&_ports_lock);
+-	      if (inp->msgh_seqno < pi->cancel_threshold)
++	      mach_port_seqno_t cancel_threshold =
++		__atomic_load_n (&pi->cancel_threshold, __ATOMIC_SEQ_CST);
++
++	      if (inp->msgh_seqno < cancel_threshold)
+ 		hurd_thread_cancel (link.thread);
+-	      pthread_mutex_unlock (&_ports_lock);
++
+ 	      status = demuxer (inp, outheadp);
+ 	      ports_end_rpc (pi, &link);
+ 	    }
+diff --git a/libports/ports.h b/libports/ports.h
+index a625b47..f02edb4 100644
+--- a/libports/ports.h
++++ b/libports/ports.h
+@@ -48,7 +48,7 @@ struct port_info
+   struct port_class *class;
+   refcounts_t refcounts;
+   mach_port_mscount_t mscount;
+-  mach_msg_seqno_t cancel_threshold;
++  mach_msg_seqno_t cancel_threshold;	/* needs atomic operations */
+   int flags;
+   mach_port_t port_right;
+   struct rpc_info *current_rpcs;
+-- 
+2.1.3
+
diff --git a/debian/patches/series b/debian/patches/series
index ef03f009..ca8c522b 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -45,3 +45,4 @@ startup-avoid-broken-puts.patch
 pfinet_dhcp.patch
 libports-payloads.patch
 proc-task-notify-0005-proc-fix-build.patch
+0001-libports-avoid-acquiring-global-lock-in-message-disp.patch