From 290db09546b260a30137d03ce97a857e6f15b648 Mon Sep 17 00:00:00 2001
From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Wed, 6 Apr 2022 12:24:42 -0300
Subject: [PATCH] nptl: Handle spurious EINTR when thread cancellation is
 disabled (BZ#29029)

Some Linux interfaces never restart after being interrupted by a signal
handler, regardless of the use of SA_RESTART [1].  It means that for
pthread cancellation, if the target thread disables cancellation with
pthread_setcancelstate and calls such interfaces (like poll or select),
it should not see spurious EINTR failures due the internal SIGCANCEL.

However recent changes made pthread_cancel to always sent the internal
signal, regardless of the target thread cancellation status or type.
To fix it, the previous semantic is restored, where the cancel signal
is only sent if the target thread has cancelation enabled in
asynchronous mode.

The cancel state and cancel type is moved back to cancelhandling
and atomic operation are used to synchronize between threads.  The
patch essentially revert the following commits:

  8c1c0aae20 nptl: Move cancel type out of cancelhandling
  2b51742531 nptl: Move cancel state out of cancelhandling
  26cfbb7162 nptl: Remove CANCELING_BITMASK

However I changed the atomic operation to follow the internal C11
semantic and removed the MACRO usage, it simplifies a bit the
resulting code (and removes another usage of the old atomic macros).

Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
and powerpc64-linux-gnu.

[1] https://man7.org/linux/man-pages/man7/signal.7.html

Reviewed-by: Florian Weimer <fweimer@redhat.com>
Tested-by: Aurelien Jarno <aurelien@aurel32.net>

(cherry-picked from commit 404656009b459658138ed1bd18f3c6cf3863e6a6)
---
 NEWS                           |   2 +
 manual/process.texi            |   3 +-
 nptl/allocatestack.c           |   2 -
 nptl/cancellation.c            |  50 +++++++---
 nptl/cleanup_defer.c           |  42 +++++++--
 nptl/descr.h                   |  41 +++++---
 nptl/libc-cleanup.c            |  39 +++++++-
 nptl/pthread_cancel.c          | 110 ++++++++++++++++------
 nptl/pthread_join_common.c     |   7 +-
 nptl/pthread_setcancelstate.c  |  26 +++++-
 nptl/pthread_setcanceltype.c   |  31 +++++-
 nptl/pthread_testcancel.c      |   9 +-
 sysdeps/nptl/dl-tls_init_tp.c  |   3 -
 sysdeps/nptl/pthreadP.h        |   2 +-
 sysdeps/pthread/Makefile       |   1 +
 sysdeps/pthread/tst-cancel29.c | 207 +++++++++++++++++++++++++++++++++++++++++
 16 files changed, 484 insertions(+), 91 deletions(-)
 create mode 100644 sysdeps/pthread/tst-cancel29.c

diff --git a/NEWS b/NEWS
index 96e0589..55aea24 100644
--- a/NEWS
+++ b/NEWS
@@ -37,6 +37,8 @@ The following bugs are resolved with this release:
     recvmsg()
   [28865] linux: _SC_NPROCESSORS_CONF and _SC_NPROCESSORS_ONLN are inaccurate
     without /sys and /proc
+  [29029] nptl: poll() spuriously returns EINTR during thread
+    cancellation and with cancellation disabled
 
 
 Version 2.34
diff --git a/manual/process.texi b/manual/process.texi
index 28c9531..9307379 100644
--- a/manual/process.texi
+++ b/manual/process.texi
@@ -68,8 +68,7 @@ until the subprogram terminates before you can do anything else.
 @c   CLEANUP_HANDLER @ascuplugin @ascuheap @acsmem
 @c    libc_cleanup_region_start @ascuplugin @ascuheap @acsmem
 @c     pthread_cleanup_push_defer @ascuplugin @ascuheap @acsmem
-@c      __pthread_testcancel @ascuplugin @ascuheap @acsmem
-@c       CANCEL_ENABLED_AND_CANCELED ok
+@c      cancel_enabled_and_canceled @ascuplugin @ascuheap @acsmem
 @c       do_cancel @ascuplugin @ascuheap @acsmem
 @c    cancel_handler ok
 @c     kill syscall ok
diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
index 554a721..9610175 100644
--- a/nptl/allocatestack.c
+++ b/nptl/allocatestack.c
@@ -120,8 +120,6 @@ get_cached_stack (size_t *sizep, void **memp)
 
   /* Cancellation handling is back to the default.  */
   result->cancelhandling = 0;
-  result->cancelstate = PTHREAD_CANCEL_ENABLE;
-  result->canceltype = PTHREAD_CANCEL_DEFERRED;
   result->cleanup = NULL;
   result->setup_failed = 0;
 
diff --git a/nptl/cancellation.c b/nptl/cancellation.c
index 0596278..e97d56f 100644
--- a/nptl/cancellation.c
+++ b/nptl/cancellation.c
@@ -31,19 +31,26 @@ int
 __pthread_enable_asynccancel (void)
 {
   struct pthread *self = THREAD_SELF;
+  int oldval = atomic_load_relaxed (&self->cancelhandling);
 
-  int oldval = THREAD_GETMEM (self, canceltype);
-  THREAD_SETMEM (self, canceltype, PTHREAD_CANCEL_ASYNCHRONOUS);
+  while (1)
+    {
+      int newval = oldval | CANCELTYPE_BITMASK;
 
-  int ch = THREAD_GETMEM (self, cancelhandling);
+      if (newval == oldval)
+	break;
 
-  if (self->cancelstate == PTHREAD_CANCEL_ENABLE
-      && (ch & CANCELED_BITMASK)
-      && !(ch & EXITING_BITMASK)
-      && !(ch & TERMINATED_BITMASK))
-    {
-      THREAD_SETMEM (self, result, PTHREAD_CANCELED);
-      __do_cancel ();
+      if (atomic_compare_exchange_weak_acquire (&self->cancelhandling,
+						&oldval, newval))
+	{
+	  if (cancel_enabled_and_canceled_and_async (newval))
+	    {
+	      self->result = PTHREAD_CANCELED;
+	      __do_cancel ();
+	    }
+
+	  break;
+	}
     }
 
   return oldval;
@@ -57,10 +64,29 @@ __pthread_disable_asynccancel (int oldtype)
 {
   /* If asynchronous cancellation was enabled before we do not have
      anything to do.  */
-  if (oldtype == PTHREAD_CANCEL_ASYNCHRONOUS)
+  if (oldtype & CANCELTYPE_BITMASK)
     return;
 
   struct pthread *self = THREAD_SELF;
-  self->canceltype = PTHREAD_CANCEL_DEFERRED;
+  int newval;
+  int oldval = atomic_load_relaxed (&self->cancelhandling);
+  do
+    {
+      newval = oldval & ~CANCELTYPE_BITMASK;
+    }
+  while (!atomic_compare_exchange_weak_acquire (&self->cancelhandling,
+						&oldval, newval));
+
+  /* We cannot return when we are being canceled.  Upon return the
+     thread might be things which would have to be undone.  The
+     following loop should loop until the cancellation signal is
+     delivered.  */
+  while (__glibc_unlikely ((newval & (CANCELING_BITMASK | CANCELED_BITMASK))
+			   == CANCELING_BITMASK))
+    {
+      futex_wait_simple ((unsigned int *) &self->cancelhandling, newval,
+			 FUTEX_PRIVATE);
+      newval = atomic_load_relaxed (&self->cancelhandling);
+    }
 }
 libc_hidden_def (__pthread_disable_asynccancel)
diff --git a/nptl/cleanup_defer.c b/nptl/cleanup_defer.c
index 7e858d0..35ba40f 100644
--- a/nptl/cleanup_defer.c
+++ b/nptl/cleanup_defer.c
@@ -31,9 +31,22 @@ ___pthread_register_cancel_defer (__pthread_unwind_buf_t *buf)
   ibuf->priv.data.prev = THREAD_GETMEM (self, cleanup_jmp_buf);
   ibuf->priv.data.cleanup = THREAD_GETMEM (self, cleanup);
 
-  /* Disable asynchronous cancellation for now.  */
-  ibuf->priv.data.canceltype = THREAD_GETMEM (self, canceltype);
-  THREAD_SETMEM (self, canceltype, PTHREAD_CANCEL_DEFERRED);
+  int cancelhandling = atomic_load_relaxed (&self->cancelhandling);
+  if (__glibc_unlikely (cancelhandling & CANCELTYPE_BITMASK))
+    {
+      int newval;
+      do
+	{
+	  newval = cancelhandling & ~CANCELTYPE_BITMASK;
+	}
+      while (!atomic_compare_exchange_weak_acquire (&self->cancelhandling,
+						    &cancelhandling,
+						    newval));
+    }
+
+  ibuf->priv.data.canceltype = (cancelhandling & CANCELTYPE_BITMASK
+				? PTHREAD_CANCEL_ASYNCHRONOUS
+				: PTHREAD_CANCEL_DEFERRED);
 
   /* Store the new cleanup handler info.  */
   THREAD_SETMEM (self, cleanup_jmp_buf, (struct pthread_unwind_buf *) buf);
@@ -55,9 +68,26 @@ ___pthread_unregister_cancel_restore (__pthread_unwind_buf_t *buf)
 
   THREAD_SETMEM (self, cleanup_jmp_buf, ibuf->priv.data.prev);
 
-  THREAD_SETMEM (self, canceltype, ibuf->priv.data.canceltype);
-  if (ibuf->priv.data.canceltype == PTHREAD_CANCEL_ASYNCHRONOUS)
-    __pthread_testcancel ();
+  if (ibuf->priv.data.canceltype == PTHREAD_CANCEL_DEFERRED)
+    return;
+
+  int cancelhandling = atomic_load_relaxed (&self->cancelhandling);
+  if (cancelhandling & CANCELTYPE_BITMASK)
+    {
+      int newval;
+      do
+	{
+	  newval = cancelhandling | CANCELTYPE_BITMASK;
+	}
+      while (!atomic_compare_exchange_weak_acquire (&self->cancelhandling,
+						    &cancelhandling, newval));
+
+      if (cancel_enabled_and_canceled (cancelhandling))
+	{
+	  self->result = PTHREAD_CANCELED;
+	  __do_cancel ();
+	}
+    }
 }
 versioned_symbol (libc, ___pthread_unregister_cancel_restore,
 		  __pthread_unregister_cancel_restore, GLIBC_2_34);
diff --git a/nptl/descr.h b/nptl/descr.h
index 4de8413..03a4358 100644
--- a/nptl/descr.h
+++ b/nptl/descr.h
@@ -277,18 +277,27 @@ struct pthread
 
   /* Flags determining processing of cancellation.  */
   int cancelhandling;
+  /* Bit set if cancellation is disabled.  */
+#define CANCELSTATE_BIT		0
+#define CANCELSTATE_BITMASK	(1 << CANCELSTATE_BIT)
+  /* Bit set if asynchronous cancellation mode is selected.  */
+#define CANCELTYPE_BIT		1
+#define CANCELTYPE_BITMASK	(1 << CANCELTYPE_BIT)
+  /* Bit set if canceling has been initiated.  */
+#define CANCELING_BIT		2
+#define CANCELING_BITMASK	(1 << CANCELING_BIT)
   /* Bit set if canceled.  */
 #define CANCELED_BIT		3
-#define CANCELED_BITMASK	(0x01 << CANCELED_BIT)
+#define CANCELED_BITMASK	(1 << CANCELED_BIT)
   /* Bit set if thread is exiting.  */
 #define EXITING_BIT		4
-#define EXITING_BITMASK		(0x01 << EXITING_BIT)
+#define EXITING_BITMASK		(1 << EXITING_BIT)
   /* Bit set if thread terminated and TCB is freed.  */
 #define TERMINATED_BIT		5
-#define TERMINATED_BITMASK	(0x01 << TERMINATED_BIT)
+#define TERMINATED_BITMASK	(1 << TERMINATED_BIT)
   /* Bit set if thread is supposed to change XID.  */
 #define SETXID_BIT		6
-#define SETXID_BITMASK		(0x01 << SETXID_BIT)
+#define SETXID_BITMASK		(1 << SETXID_BIT)
 
   /* Flags.  Including those copied from the thread attribute.  */
   int flags;
@@ -388,14 +397,6 @@ struct pthread
   /* Indicates whether is a C11 thread created by thrd_creat.  */
   bool c11;
 
-  /* Thread cancel state (PTHREAD_CANCEL_ENABLE or
-     PTHREAD_CANCEL_DISABLE).  */
-  unsigned char cancelstate;
-
-  /* Thread cancel type (PTHREAD_CANCEL_DEFERRED or
-     PTHREAD_CANCEL_ASYNCHRONOUS).  */
-  unsigned char canceltype;
-
   /* Used in __pthread_kill_internal to detected a thread that has
      exited or is about to exit.  exit_lock must only be acquired
      after blocking signals.  */
@@ -412,6 +413,22 @@ struct pthread
   (sizeof (struct pthread) - offsetof (struct pthread, end_padding))
 } __attribute ((aligned (TCB_ALIGNMENT)));
 
+static inline bool
+cancel_enabled_and_canceled (int value)
+{
+  return (value & (CANCELSTATE_BITMASK | CANCELED_BITMASK | EXITING_BITMASK
+		   | TERMINATED_BITMASK))
+    == CANCELED_BITMASK;
+}
+
+static inline bool
+cancel_enabled_and_canceled_and_async (int value)
+{
+  return ((value) & (CANCELSTATE_BITMASK | CANCELTYPE_BITMASK | CANCELED_BITMASK
+		     | EXITING_BITMASK | TERMINATED_BITMASK))
+    == (CANCELTYPE_BITMASK | CANCELED_BITMASK);
+}
+
 /* This yields the pointer that TLS support code calls the thread pointer.  */
 #if TLS_TCB_AT_TP
 # define TLS_TPADJ(pd) (pd)
diff --git a/nptl/libc-cleanup.c b/nptl/libc-cleanup.c
index 180d15b..fccb1ab 100644
--- a/nptl/libc-cleanup.c
+++ b/nptl/libc-cleanup.c
@@ -27,9 +27,24 @@ __libc_cleanup_push_defer (struct _pthread_cleanup_buffer *buffer)
 
   buffer->__prev = THREAD_GETMEM (self, cleanup);
 
+  int cancelhandling = atomic_load_relaxed (&self->cancelhandling);
+
   /* Disable asynchronous cancellation for now.  */
-  buffer->__canceltype = THREAD_GETMEM (self, canceltype);
-  THREAD_SETMEM (self, canceltype, PTHREAD_CANCEL_DEFERRED);
+  if (__glibc_unlikely (cancelhandling & CANCELTYPE_BITMASK))
+    {
+      int newval;
+      do
+	{
+	  newval = cancelhandling & ~CANCELTYPE_BITMASK;
+	}
+      while (!atomic_compare_exchange_weak_acquire (&self->cancelhandling,
+						    &cancelhandling,
+						    newval));
+    }
+
+  buffer->__canceltype = (cancelhandling & CANCELTYPE_BITMASK
+			  ? PTHREAD_CANCEL_ASYNCHRONOUS
+			  : PTHREAD_CANCEL_DEFERRED);
 
   THREAD_SETMEM (self, cleanup, buffer);
 }
@@ -42,8 +57,22 @@ __libc_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer)
 
   THREAD_SETMEM (self, cleanup, buffer->__prev);
 
-  THREAD_SETMEM (self, canceltype, buffer->__canceltype);
-  if (buffer->__canceltype == PTHREAD_CANCEL_ASYNCHRONOUS)
-      __pthread_testcancel ();
+  int cancelhandling = atomic_load_relaxed (&self->cancelhandling);
+  if (cancelhandling & CANCELTYPE_BITMASK)
+    {
+      int newval;
+      do
+	{
+	  newval = cancelhandling | CANCELTYPE_BITMASK;
+	}
+      while (!atomic_compare_exchange_weak_acquire (&self->cancelhandling,
+						    &cancelhandling, newval));
+
+      if (cancel_enabled_and_canceled (cancelhandling))
+	{
+	  self->result = PTHREAD_CANCELED;
+	  __do_cancel ();
+	}
+    }
 }
 libc_hidden_def (__libc_cleanup_pop_restore)
diff --git a/nptl/pthread_cancel.c b/nptl/pthread_cancel.c
index 9bac6e3..2680b55 100644
--- a/nptl/pthread_cancel.c
+++ b/nptl/pthread_cancel.c
@@ -43,18 +43,29 @@ sigcancel_handler (int sig, siginfo_t *si, void *ctx)
 
   struct pthread *self = THREAD_SELF;
 
-  int ch = atomic_load_relaxed (&self->cancelhandling);
-  /* Cancelation not enabled, not cancelled, or already exitting.  */
-  if (self->cancelstate == PTHREAD_CANCEL_DISABLE
-      || (ch & CANCELED_BITMASK) == 0
-      || (ch & EXITING_BITMASK) != 0)
-    return;
-
-  /* Set the return value.  */
-  THREAD_SETMEM (self, result, PTHREAD_CANCELED);
-  /* Make sure asynchronous cancellation is still enabled.  */
-  if (self->canceltype == PTHREAD_CANCEL_ASYNCHRONOUS)
-    __do_cancel ();
+  int oldval = atomic_load_relaxed (&self->cancelhandling);
+  while (1)
+    {
+      /* We are canceled now.  When canceled by another thread this flag
+	 is already set but if the signal is directly send (internally or
+	 from another process) is has to be done here.  */
+      int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
+
+      if (oldval == newval || (oldval & EXITING_BITMASK) != 0)
+	/* Already canceled or exiting.  */
+	break;
+
+      if (atomic_compare_exchange_weak_acquire (&self->cancelhandling,
+						&oldval, newval))
+	{
+	  self->result = PTHREAD_CANCELED;
+
+	  /* Make sure asynchronous cancellation is still enabled.  */
+	  if ((oldval & CANCELTYPE_BITMASK) != 0)
+	    /* Run the registered destructors and terminate the thread.  */
+	    __do_cancel ();
+	}
+    }
 }
 
 int
@@ -93,29 +104,70 @@ __pthread_cancel (pthread_t th)
   }
 #endif
 
-  int oldch = atomic_fetch_or_acquire (&pd->cancelhandling, CANCELED_BITMASK);
-  if ((oldch & CANCELED_BITMASK) != 0)
-    return 0;
-
-  if (pd == THREAD_SELF)
+  /* Some syscalls are never restarted after being interrupted by a signal
+     handler, regardless of the use of SA_RESTART (they always fail with
+     EINTR).  So pthread_cancel cannot send SIGCANCEL unless the cancellation
+     is enabled and set as asynchronous (in this case the cancellation will
+     be acted in the cancellation handler instead by the syscall wrapper).
+     Otherwise the target thread is set as 'cancelling' (CANCELING_BITMASK)
+     by atomically setting 'cancelhandling' and the cancelation will be acted
+     upon on next cancellation entrypoing in the target thread.
+
+     It also requires to atomically check if cancellation is enabled and
+     asynchronous, so both cancellation state and type are tracked on
+     'cancelhandling'.  */
+
+  int result = 0;
+  int oldval = atomic_load_relaxed (&pd->cancelhandling);
+  int newval;
+  do
     {
-      /* A single-threaded process should be able to kill itself, since there
-	 is nothing in the POSIX specification that says that it cannot.  So
-	 we set multiple_threads to true so that cancellation points get
-	 executed.  */
-      THREAD_SETMEM (THREAD_SELF, header.multiple_threads, 1);
+      newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
+      if (oldval == newval)
+	break;
+
+      /* If the cancellation is handled asynchronously just send a
+	 signal.  We avoid this if possible since it's more
+	 expensive.  */
+      if (cancel_enabled_and_canceled_and_async (newval))
+	{
+	  /* Mark the cancellation as "in progress".  */
+	  int newval2 = oldval | CANCELING_BITMASK;
+	  if (!atomic_compare_exchange_weak_acquire (&pd->cancelhandling,
+						     &oldval, newval2))
+	    continue;
+
+	  if (pd == THREAD_SELF)
+	    /* This is not merely an optimization: An application may
+	       call pthread_cancel (pthread_self ()) without calling
+	       pthread_create, so the signal handler may not have been
+	       set up for a self-cancel.  */
+	    {
+	      pd->result = PTHREAD_CANCELED;
+	      if ((newval & CANCELTYPE_BITMASK) != 0)
+		__do_cancel ();
+	    }
+	  else
+	    /* The cancellation handler will take care of marking the
+	       thread as canceled.  */
+	    result = __pthread_kill_internal (th, SIGCANCEL);
+
+	  break;
+	}
+
+	/* A single-threaded process should be able to kill itself, since
+	   there is nothing in the POSIX specification that says that it
+	   cannot.  So we set multiple_threads to true so that cancellation
+	   points get executed.  */
+	THREAD_SETMEM (THREAD_SELF, header.multiple_threads, 1);
 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
       __libc_multiple_threads = 1;
 #endif
-
-      THREAD_SETMEM (pd, result, PTHREAD_CANCELED);
-      if (pd->cancelstate == PTHREAD_CANCEL_ENABLE
-	  && pd->canceltype == PTHREAD_CANCEL_ASYNCHRONOUS)
-	__do_cancel ();
-      return 0;
     }
+  while (!atomic_compare_exchange_weak_acquire (&pd->cancelhandling, &oldval,
+						newval));
 
-  return __pthread_kill_internal (th, SIGCANCEL);
+  return result;
 }
 versioned_symbol (libc, __pthread_cancel, pthread_cancel, GLIBC_2_34);
 
diff --git a/nptl/pthread_join_common.c b/nptl/pthread_join_common.c
index 7303069..617056e 100644
--- a/nptl/pthread_join_common.c
+++ b/nptl/pthread_join_common.c
@@ -57,12 +57,9 @@ __pthread_clockjoin_ex (pthread_t threadid, void **thread_return,
   if ((pd == self
        || (self->joinid == pd
 	   && (pd->cancelhandling
-	       & (CANCELED_BITMASK | EXITING_BITMASK
+	       & (CANCELING_BITMASK | CANCELED_BITMASK | EXITING_BITMASK
 		  | TERMINATED_BITMASK)) == 0))
-      && !(self->cancelstate == PTHREAD_CANCEL_ENABLE
-	   && (pd->cancelhandling & (CANCELED_BITMASK | EXITING_BITMASK
-				     | TERMINATED_BITMASK))
-	       == CANCELED_BITMASK))
+      && !cancel_enabled_and_canceled (self->cancelhandling))
     /* This is a deadlock situation.  The threads are waiting for each
        other to finish.  Note that this is a "may" error.  To be 100%
        sure we catch this error we would have to lock the data
diff --git a/nptl/pthread_setcancelstate.c b/nptl/pthread_setcancelstate.c
index 7e2b6e4..cb567be 100644
--- a/nptl/pthread_setcancelstate.c
+++ b/nptl/pthread_setcancelstate.c
@@ -31,9 +31,29 @@ __pthread_setcancelstate (int state, int *oldstate)
 
   self = THREAD_SELF;
 
-  if (oldstate != NULL)
-    *oldstate = self->cancelstate;
-  self->cancelstate = state;
+  int oldval = atomic_load_relaxed (&self->cancelhandling);
+  while (1)
+    {
+      int newval = (state == PTHREAD_CANCEL_DISABLE
+		    ? oldval | CANCELSTATE_BITMASK
+		    : oldval & ~CANCELSTATE_BITMASK);
+
+      if (oldstate != NULL)
+	*oldstate = ((oldval & CANCELSTATE_BITMASK)
+		     ? PTHREAD_CANCEL_DISABLE : PTHREAD_CANCEL_ENABLE);
+
+      if (oldval == newval)
+	break;
+
+      if (atomic_compare_exchange_weak_acquire (&self->cancelhandling,
+						&oldval, newval))
+	{
+	  if (cancel_enabled_and_canceled_and_async (newval))
+	    __do_cancel ();
+
+	  break;
+	}
+    }
 
   return 0;
 }
diff --git a/nptl/pthread_setcanceltype.c b/nptl/pthread_setcanceltype.c
index e7b24ae..e08ff7b 100644
--- a/nptl/pthread_setcanceltype.c
+++ b/nptl/pthread_setcanceltype.c
@@ -29,11 +29,32 @@ __pthread_setcanceltype (int type, int *oldtype)
 
   volatile struct pthread *self = THREAD_SELF;
 
-  if (oldtype != NULL)
-    *oldtype = self->canceltype;
-  self->canceltype = type;
-  if (type == PTHREAD_CANCEL_ASYNCHRONOUS)
-    __pthread_testcancel ();
+  int oldval = atomic_load_relaxed (&self->cancelhandling);
+  while (1)
+    {
+      int newval = (type == PTHREAD_CANCEL_ASYNCHRONOUS
+		    ? oldval | CANCELTYPE_BITMASK
+		    : oldval & ~CANCELTYPE_BITMASK);
+
+      if (oldtype != NULL)
+	*oldtype = ((oldval & CANCELTYPE_BITMASK)
+		    ? PTHREAD_CANCEL_ASYNCHRONOUS : PTHREAD_CANCEL_DEFERRED);
+
+      if (oldval == newval)
+	break;
+
+      if (atomic_compare_exchange_weak_acquire (&self->cancelhandling,
+						&oldval, newval))
+	{
+	  if (cancel_enabled_and_canceled_and_async (newval))
+	    {
+	      THREAD_SETMEM (self, result, PTHREAD_CANCELED);
+	      __do_cancel ();
+	    }
+
+	  break;
+	}
+    }
 
   return 0;
 }
diff --git a/nptl/pthread_testcancel.c b/nptl/pthread_testcancel.c
index 31185d8..2523021 100644
--- a/nptl/pthread_testcancel.c
+++ b/nptl/pthread_testcancel.c
@@ -24,13 +24,10 @@ void
 ___pthread_testcancel (void)
 {
   struct pthread *self = THREAD_SELF;
-  int cancelhandling = THREAD_GETMEM (self, cancelhandling);
-  if (self->cancelstate == PTHREAD_CANCEL_ENABLE
-      && (cancelhandling & CANCELED_BITMASK)
-      && !(cancelhandling & EXITING_BITMASK)
-      && !(cancelhandling & TERMINATED_BITMASK))
+  int cancelhandling = atomic_load_relaxed (&self->cancelhandling);
+  if (cancel_enabled_and_canceled (cancelhandling))
     {
-      THREAD_SETMEM (self, result, PTHREAD_CANCELED);
+      self->result = PTHREAD_CANCELED;
       __do_cancel ();
     }
 }
diff --git a/sysdeps/nptl/dl-tls_init_tp.c b/sysdeps/nptl/dl-tls_init_tp.c
index ca494dd..c2054f8 100644
--- a/sysdeps/nptl/dl-tls_init_tp.c
+++ b/sysdeps/nptl/dl-tls_init_tp.c
@@ -94,7 +94,4 @@ __tls_init_tp (void)
      It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
      purposes this is good enough.  */
   THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
-
-  THREAD_SETMEM (pd, cancelstate, PTHREAD_CANCEL_ENABLE);
-  THREAD_SETMEM (pd, canceltype, PTHREAD_CANCEL_DEFERRED);
 }
diff --git a/sysdeps/nptl/pthreadP.h b/sysdeps/nptl/pthreadP.h
index 374657a..b968afc 100644
--- a/sysdeps/nptl/pthreadP.h
+++ b/sysdeps/nptl/pthreadP.h
@@ -276,7 +276,7 @@ __do_cancel (void)
   struct pthread *self = THREAD_SELF;
 
   /* Make sure we get no more cancellations.  */
-  THREAD_ATOMIC_BIT_SET (self, cancelhandling, EXITING_BIT);
+  atomic_bit_set (&self->cancelhandling, EXITING_BIT);
 
   __pthread_unwind ((__pthread_unwind_buf_t *)
 		    THREAD_GETMEM (self, cleanup_jmp_buf));
diff --git a/sysdeps/pthread/Makefile b/sysdeps/pthread/Makefile
index c657101..00419c4 100644
--- a/sysdeps/pthread/Makefile
+++ b/sysdeps/pthread/Makefile
@@ -69,6 +69,7 @@ tests += tst-cnd-basic tst-mtx-trylock tst-cnd-broadcast \
 	 tst-cancel12 tst-cancel13 tst-cancel14 tst-cancel15 tst-cancel16 \
 	 tst-cancel18 tst-cancel19 tst-cancel20 tst-cancel21 \
 	 tst-cancel22 tst-cancel23 tst-cancel26 tst-cancel27 tst-cancel28 \
+	 tst-cancel29 \
 	 tst-cleanup0 tst-cleanup1 tst-cleanup2 tst-cleanup3 \
 	 tst-clock1 \
 	 tst-cond-except \
diff --git a/sysdeps/pthread/tst-cancel29.c b/sysdeps/pthread/tst-cancel29.c
new file mode 100644
index 0000000..4f0d99e
--- /dev/null
+++ b/sysdeps/pthread/tst-cancel29.c
@@ -0,0 +1,207 @@
+/* Check if a thread that disables cancellation and which call functions
+   that might be interrupted by a signal do not see the internal SIGCANCEL.
+
+   Copyright (C) 2022 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <array_length.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <poll.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <support/temp_file.h>
+#include <support/xthread.h>
+#include <sys/socket.h>
+#include <signal.h>
+#include <stdio.h>
+#include <unistd.h>
+
+/* On Linux some interfaces are never restarted after being interrupted by
+   a signal handler, regardless of the use of SA_RESTART.  It means that
+   if asynchronous cancellation is not enabled, the pthread_cancel can not
+   set the internal SIGCANCEL otherwise the interface might see a spurious
+   EINTR failure.  */
+
+static pthread_barrier_t b;
+
+/* Cleanup handling test.  */
+static int cl_called;
+static void
+cl (void *arg)
+{
+  ++cl_called;
+}
+
+static void *
+tf_sigtimedwait (void *arg)
+{
+  pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, NULL);
+  xpthread_barrier_wait (&b);
+
+  int r;
+  pthread_cleanup_push (cl, NULL);
+
+  sigset_t mask;
+  sigemptyset (&mask);
+  r = sigtimedwait (&mask, NULL, &(struct timespec) { 0, 250000000 });
+  if (r != -1)
+    return (void*) -1;
+  if (errno != EAGAIN)
+    return (void*) -2;
+
+  pthread_cleanup_pop (0);
+  return NULL;
+}
+
+static void *
+tf_poll (void *arg)
+{
+  pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, NULL);
+  xpthread_barrier_wait (&b);
+
+  int r;
+  pthread_cleanup_push (cl, NULL);
+
+  r = poll (NULL, 0, 250);
+  if (r != 0)
+    return (void*) -1;
+
+  pthread_cleanup_pop (0);
+  return NULL;
+}
+
+static void *
+tf_ppoll (void *arg)
+{
+  pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, NULL);
+
+  xpthread_barrier_wait (&b);
+
+  int r;
+  pthread_cleanup_push (cl, NULL);
+
+  r = ppoll (NULL, 0, &(struct timespec) { 0, 250000000 }, NULL);
+  if (r != 0)
+    return (void*) -1;
+
+  pthread_cleanup_pop (0);
+  return NULL;
+}
+
+static void *
+tf_select (void *arg)
+{
+  pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, NULL);
+  xpthread_barrier_wait (&b);
+
+  int r;
+  pthread_cleanup_push (cl, NULL);
+
+  r = select (0, NULL, NULL, NULL, &(struct timeval) { 0, 250000 });
+  if (r != 0)
+    return (void*) -1;
+
+  pthread_cleanup_pop (0);
+  return NULL;
+}
+
+static void *
+tf_pselect (void *arg)
+{
+  pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, NULL);
+  xpthread_barrier_wait (&b);
+
+  int r;
+  pthread_cleanup_push (cl, NULL);
+
+  r = pselect (0, NULL, NULL, NULL, &(struct timespec) { 0, 250000000 }, NULL);
+  if (r != 0)
+    return (void*) -1;
+
+  pthread_cleanup_pop (0);
+  return NULL;
+}
+
+static void *
+tf_clock_nanosleep (void *arg)
+{
+  pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, NULL);
+  xpthread_barrier_wait (&b);
+
+  int r;
+  pthread_cleanup_push (cl, NULL);
+
+  r = clock_nanosleep (CLOCK_REALTIME, 0, &(struct timespec) { 0, 250000000 },
+		       NULL);
+  if (r != 0)
+    return (void*) -1;
+
+  pthread_cleanup_pop (0);
+  return NULL;
+}
+
+struct cancel_test_t
+{
+  const char *name;
+  void * (*cf) (void *);
+} tests[] =
+{
+  { "sigtimedwait",    tf_sigtimedwait,    },
+  { "poll",            tf_poll,            },
+  { "ppoll",           tf_ppoll,           },
+  { "select",          tf_select,          },
+  { "pselect",         tf_pselect  ,       },
+  { "clock_nanosleep", tf_clock_nanosleep, },
+};
+
+static int
+do_test (void)
+{
+  for (int i = 0; i < array_length (tests); i++)
+    {
+      xpthread_barrier_init (&b, NULL, 2);
+
+      cl_called = 0;
+
+      pthread_t th = xpthread_create (NULL, tests[i].cf, NULL);
+
+      xpthread_barrier_wait (&b);
+
+      struct timespec ts = { .tv_sec = 0, .tv_nsec = 100000000 };
+      while (nanosleep (&ts, &ts) != 0)
+	continue;
+
+      xpthread_cancel (th);
+
+      void *status = xpthread_join (th);
+      if (status != NULL)
+	printf ("test '%s' failed: %" PRIdPTR "\n", tests[i].name,
+		(intptr_t) status);
+      TEST_VERIFY (status == NULL);
+
+      xpthread_barrier_destroy (&b);
+
+      TEST_COMPARE (cl_called, 0);
+
+      printf ("in-time cancel test of '%s' successful\n", tests[i].name);
+    }
+
+  return 0;
+}
+
+#include <support/test-driver.c>
-- 
1.8.3.1

