Re: [uclibc-ng-devel] [PATCH v2] Fix subtle race in tst-cancel2 / tst-cancelx2

On 12/08/2017 10:07 AM, Vineet Gupta wrote: When ran on ARC, these tests would ocassionally fail | [ARCLinux]# for i in 1 2 3 4 5 ; do ./tst-cancel2; echo $?; done | write succeeded | result is wrong: expected 0xffffffff, got 0x1 | 1 <-- fail | 0 <-- pass | 0 <--- pass | 0 <-- pass | write succeeded | result is wrong: expected 0xffffffff, got 0x1 | 1 <-- fail Same test (which originated form glibc) doesn't fail in glibc builds. Turns out there's a subtle race in uclibc version The test creates a new thread, makes it do a looong write call, and parent then cancels the thread, expecting it to unwind out of write call cleanly. However the write (even for 10k bytes) could finish before parent gets a chance to resume and/or cancel it, causing the occasional failure. Fix this subtelty by making it write not just once but forever. Cc: Cupertino Miranda &lt;cmiranda(a)synopsys.com&gt; Signed-off-by: Vineet Gupta &lt;vgupta(a)synopsys.com&gt; --- Change since v1: fix typos in changelogs ---

test/nptl/tst-cancel2.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/test/nptl/tst-cancel2.c b/test/nptl/tst-cancel2.c index 45c9e8ea957a..08dd13b10f37 100644 --- a/test/nptl/tst-cancel2.c +++ b/test/nptl/tst-cancel2.c @@ -32,11 +32,7 @@ tf (void *arg) write blocks. */ char buf[100000]; - if (write (fd[1], buf, sizeof (buf)) == sizeof (buf)) - { - puts ("write succeeded"); - return (void *) 1l; - } + while (write (fd[1], buf, sizeof (buf)) > 0); return (void *) 42l; }