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.
2019-01-03 Adhemerval Zanella <adhemerval.zanella@linaro.org>
+ * 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.
+
* io/creat.c (LIBC_CANCEL_HANDLED): Remove macro.
* io/ppoll.c (LIBC_CANCEL_HANDLED): Likewise.
* misc/pselect.c (LIBC_CANCEL_HANDLED): Likewise.
FAIL ();
return;
}
- /* Do not check name for signal trampoline. */
- i = 2;
- if (!match (symbols[i++], "read"))
+
+ /* Do not check name for signal trampoline or cancellable syscall
+ wrappers (__syscall_cancel*). */
+ for (; i < n - 1; i++)
+ if (match (symbols[i], "read"))
+ break;
+ if (i == n - 1)
{
- /* Perhaps symbols[2] is __kernel_vsyscall? */
- if (!match (symbols[i++], "read"))
- {
- FAIL ();
- return;
- }
+ FAIL ();
+ return;
}
+
for (; i < n - 1; i++)
if (!match (symbols[i], "fn"))
{
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);
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);