Introduce gsync-based locks to glibc.

From: Agustina Arzille <avarzille@riseup.net>

* hurd/Makefile: Add hurdlock.
* hurd/Versions: Added new entry to export the above interface.
* hurd/hurdlock.c: New file.
* hurd/hurdlock.h: New file.
* hurd/hurdpid.c: Include <lowlevellock.h>
  (_S_msg_proc_newids): Use lll_wait to synchronize.
* hurd/hurdsig.c: (reauth_proc): Use __mutex_lock and __mutex_unlock.
* hurd/setauth.c: Include <hurdlock.h>, use integer for synchronization.
* hurd/sysvshm.c: Include <hurdlock.h>, use integer for synchronization.
* mach/Makefile: Remove unneeded file
* mach/lock-intern.h: Use lll to implement spinlocks.
* mach/lowlevellock.h: New file
* mach/mutex-init.c: Rewrite mutex initialization.
* sysdeps/mach/Makefile: Add libmachuser as dependencies for some libs.
* sysdeps/mach/bits/libc-lock.h: Reimplemented libc internal locks
  with lll, cleanup routines now use gcc's cleanup attribute
* sysdeps/mach/hurd/bits/errno.h: New errno values.
* sysdeps/mach/hurd/bits/libc-lock.h: Removed file.
* sysdeps/mach/hurd/malloc-machine.h: Reimplemented malloc locks.
* sysdeps/mach/hurd/setpgid.c: (setpgid): Use gsync for synchronization.
* sysdeps/mach/hurd/setsid.c: (setsid): Likewise.

1 files changed, 247 insertions, 0 deletions

diff --git a/hurd/hurdlock.c b/hurd/hurdlock.c
new file mode 100644
index 0000000000..d6e47316ea
--- /dev/null
+++ b/hurd/hurdlock.c
@@ -0,0 +1,247 @@
+/* Copyright (C) 1999-2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include "hurdlock.h"
+#include <hurd.h>
+#include <time.h>
+#include <errno.h>
+
+int lll_xwait (void *ptr, int lo, int hi, int flags)
+{
+  return (__gsync_wait (__mach_task_self (),
+    (vm_offset_t)ptr, lo, hi, 0, flags | GSYNC_QUAD));
+}
+
+int lll_timed_wait (void *ptr, int val, int mlsec, int flags)
+{
+  return (__gsync_wait (__mach_task_self (),
+    (vm_offset_t)ptr, val, 0, mlsec, flags | GSYNC_TIMED));
+}
+
+int lll_timed_xwait (void *ptr, int lo,
+  int hi, int mlsec, int flags)
+{
+  return (__gsync_wait (__mach_task_self (), (vm_offset_t)ptr,
+    lo, hi, mlsec, flags | GSYNC_TIMED | GSYNC_QUAD));
+}
+
+/* Convert an absolute timeout in nanoseconds to a relative
+ * timeout in milliseconds. */
+static inline int __attribute__ ((gnu_inline))
+compute_reltime (const struct timespec *abstime, clockid_t clk)
+{
+  struct timespec ts;
+  __clock_gettime (clk, &ts);
+
+  ts.tv_sec = abstime->tv_sec - ts.tv_sec;
+  ts.tv_nsec = abstime->tv_nsec - ts.tv_nsec;
+
+  if (ts.tv_nsec < 0)
+    {
+      --ts.tv_sec;
+      ts.tv_nsec += 1000000000;
+    }
+
+  return (ts.tv_sec < 0 ? -1 :
+    (int)(ts.tv_sec * 1000 + ts.tv_nsec / 1000000));
+}
+
+int __lll_abstimed_wait (void *ptr, int val,
+  const struct timespec *tsp, int flags, int clk)
+{
+  int mlsec = compute_reltime (tsp, clk);
+  return (mlsec < 0 ? KERN_TIMEDOUT :
+    lll_timed_wait (ptr, val, mlsec, flags));
+}
+
+int __lll_abstimed_xwait (void *ptr, int lo, int hi,
+  const struct timespec *tsp, int flags, int clk)
+{
+  int mlsec = compute_reltime (tsp, clk);
+  return (mlsec < 0 ? KERN_TIMEDOUT :
+    lll_timed_xwait (ptr, lo, hi, mlsec, flags));
+}
+
+int __lll_abstimed_lock (void *ptr,
+  const struct timespec *tsp, int flags, int clk)
+{
+  if (lll_trylock (ptr) == 0)
+    return (0);
+
+  while (1)
+    {
+      if (atomic_exchange_acq ((int *)ptr, 2) == 0)
+        return (0);
+      else if (tsp->tv_nsec < 0 || tsp->tv_nsec >= 1000000000)
+        return (EINVAL);
+
+      int mlsec = compute_reltime (tsp, clk);
+      if (mlsec < 0 || lll_timed_wait (ptr,
+          2, mlsec, flags) == KERN_TIMEDOUT)
+        return (ETIMEDOUT);
+    }
+}
+
+void lll_set_wake (void *ptr, int val, int flags)
+{
+  __gsync_wake (__mach_task_self (),
+    (vm_offset_t)ptr, val, flags | GSYNC_MUTATE);
+}
+
+void lll_requeue (void *src, void *dst, int wake_one, int flags)
+{
+  __gsync_requeue (__mach_task_self (), (vm_offset_t)src,
+    (vm_offset_t)dst, (boolean_t)wake_one, flags);
+}
+
+/* Robust locks. */
+
+extern int __getpid (void) __attribute__ ((const));
+extern task_t __pid2task (int);
+
+/* Test if a given process id is still valid. */
+static inline int valid_pid (int pid)
+{
+  task_t task = __pid2task (pid);
+  if (task == MACH_PORT_NULL)
+    return (0);
+
+  __mach_port_deallocate (__mach_task_self (), task);
+  return (1);
+}
+
+/* Robust locks have currently no support from the kernel; they
+ * are simply implemented with periodic polling. When sleeping, the
+ * maximum blocking time is determined by this constant. */
+#define MAX_WAIT_TIME   1500
+
+int lll_robust_lock (void *ptr, int flags)
+{
+  int *iptr = (int *)ptr;
+  int id = __getpid ();
+  int wait_time = 25;
+  unsigned int val;
+
+  /* Try to set the lock word to our PID if it's clear. Otherwise,
+   * mark it as having waiters. */
+  while (1)
+    {
+      val = *iptr;
+      if (!val && atomic_compare_and_exchange_bool_acq (iptr, id, 0) == 0)
+        return (0);
+      else if (atomic_compare_and_exchange_bool_acq (iptr,
+          val | LLL_WAITERS, val) == 0)
+        break;
+    }
+
+  for (id |= LLL_WAITERS ; ; )
+    {
+      val = *iptr;
+      if (!val && atomic_compare_and_exchange_bool_acq (iptr, id, 0) == 0)
+        return (0);
+      else if (val && !valid_pid (val & LLL_OWNER_MASK))
+        {
+          if (atomic_compare_and_exchange_bool_acq (iptr, id, val) == 0)
+            return (EOWNERDEAD);
+        }
+      else
+        {
+          lll_timed_wait (iptr, val, wait_time, flags);
+          if (wait_time < MAX_WAIT_TIME)
+            wait_time <<= 1;
+        }
+    }
+}
+
+int __lll_robust_abstimed_lock (void *ptr,
+  const struct timespec *tsp, int flags, int clk)
+{
+  int *iptr = (int *)ptr;
+  int id = __getpid ();
+  int wait_time = 25;
+  unsigned int val;
+
+  while (1)
+    {
+      val = *iptr;
+      if (!val && atomic_compare_and_exchange_bool_acq (iptr, id, 0) == 0)
+        return (0);
+      else if (atomic_compare_and_exchange_bool_acq (iptr,
+          val | LLL_WAITERS, val) == 0)
+        break;
+    }
+
+  for (id |= LLL_WAITERS ; ; )
+    {
+      val = *iptr;
+      if (!val && atomic_compare_and_exchange_bool_acq (iptr, id, 0) == 0)
+        return (0);
+      else if (val && !valid_pid (val & LLL_OWNER_MASK))
+        {
+          if (atomic_compare_and_exchange_bool_acq (iptr, id, val) == 0)
+            return (EOWNERDEAD);
+        }
+      else
+        {
+          int mlsec = compute_reltime (tsp, clk);
+          if (mlsec < 0)
+            return (ETIMEDOUT);
+          else if (mlsec > wait_time)
+            mlsec = wait_time;
+
+          int res = lll_timed_wait (iptr, val, mlsec, flags);
+          if (res == KERN_TIMEDOUT)
+            return (ETIMEDOUT);
+          else if (wait_time < MAX_WAIT_TIME)
+            wait_time <<= 1;
+        }
+    }
+}
+
+int lll_robust_trylock (void *ptr)
+{
+  int *iptr = (int *)ptr;
+  int id = __getpid ();
+  unsigned int val = *iptr;
+
+  if (!val)
+    {
+      if (atomic_compare_and_exchange_bool_acq (iptr, id, 0) == 0)
+        return (0);
+    }
+  else if (!valid_pid (val & LLL_OWNER_MASK) &&
+      atomic_compare_and_exchange_bool_acq (iptr, id, val) == 0)
+    return (EOWNERDEAD);
+
+  return (EBUSY);
+}
+
+void lll_robust_unlock (void *ptr, int flags)
+{
+  while (1)
+    {
+      unsigned int val = *(unsigned int *)ptr;
+      if (val & LLL_WAITERS)
+        {
+          lll_set_wake (ptr, 0, flags);
+          break;
+        }
+      else if (atomic_compare_and_exchange_bool_rel ((int *)ptr, 0, val) == 0)
+        break;
+    }
+}
+