nptl: Fix testcases for new pthread cancellation mechanism

With upcoming fix for BZ#12683, pthread cancellation does not act for:

  1. If syscall is blocked but with some side effects already having
     taken place (e.g. a partial read or write).
  2. After the syscall has returned.

The main change is due the fact programs need to act in syscalls with
side-effects (for instance, to avoid leak of allocated resources or
handle partial read/write).

This patch changes the NPTL testcase that assumes the old behavior and
also changes the tst-backtrace{5,6} to ignore the cancellable wrappers.

Checked on i686-linux-gnu, x86_64-linux-gnu, x86_64-linux-gnux32,
aarch64-linux-gnu, arm-linux-gnueabihf, powerpc64le-linux-gnu,
powerpc-linux-gnu, sparcv9-linux-gnu, and sparc64-linux-gnu.

	* debug/tst-backtrace5.c (handle_signal): Avoid cancellable wrappers
	in backtrace analysis.
	* nptl/tst-cancel4.c (tf_write): Handle cancelled syscall with
	side-effects.
	(tf_send): Likewise.

1 files changed, 8 insertions, 0 deletions

diff --git a/nptl/tst-cancel4.c b/nptl/tst-cancel4.c
index a0fc30fab9..60a965d23a 100644
--- a/nptl/tst-cancel4.c
+++ b/nptl/tst-cancel4.c
@@ -166,6 +166,10 @@ tf_write  (void *arg)
   char buf[WRITE_BUFFER_SIZE];
   memset (buf, '\0', sizeof (buf));
   s = write (fd, buf, sizeof (buf));
+  /* The write can return a value higher than 0 (meaning partial write)
+     due to the SIGCANCEL, but the thread may still be pending
+     cancellation.  */
+  pthread_testcancel ();
 
   pthread_cleanup_pop (0);
 
@@ -743,6 +747,10 @@ tf_send (void *arg)
   char mem[WRITE_BUFFER_SIZE];
 
   send (tempfd2, mem, arg == NULL ? sizeof (mem) : 1, 0);
+  /* The send can return a value higher than 0 (meaning partial send)
+     due to the SIGCANCEL, but the thread may still be pending
+     cancellation.  */
+  pthread_testcancel ();
 
   pthread_cleanup_pop (0);