Patchwork Go patch committed: Update libgo to 1.1.1

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Submitter Uros Bizjak
Date July 24, 2013, 9:24 a.m.
Message ID <CAFULd4aa+iWm+uASpNmpMdPH0=fCdicyz81Cj_7R=45YAvcpgQ@mail.gmail.com>
Download mbox | patch
Permalink /patch/261394/
State New
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Comments

Uros Bizjak - July 24, 2013, 9:24 a.m.
On Wed, Jul 24, 2013 at 9:09 AM, Uros Bizjak <ubizjak@gmail.com> wrote:

>>> The test was re-run with GOTESTFLAGS=--keep. When running the
>>> resulting a.out with "strace -f -o strace-x86_64 ./a.out" from the
>>> saved test directory, the test behaved in the same way as on alpha -
>>> it hever finished. I have attached the resulting trace (the test was
>>> killed with ctrl-c after some time).
>>
>> Thanks.  The problematic test is TestLinuxSendfile in
>> libgo/net/http/fs_test.go.  That test binary invokes itself using
>> strace.  In the trace here, that strace fails:
>>
>> 8511  ptrace(PTRACE_TRACEME, 0, 0, 0)   = -1 EPERM (Operation not permitted)
>> 8511  write(2, "strace: test_ptrace_setoptions_f"..., 96) = 96
>>
>> The strace is supposed to start up a little server, and the test
>> binary tries to connect to that server.  Since the server hasn't
>> started, the test times out.
>>
>> The strace invocation is
>>
>> strace -f -q -e trace=sendfile,sendfile64 ./a.out
>> -test.run=TestLinuxSendfileChild
>>
>> Any idea why that would fail?

It looks you can't trace a traced process:

$ strace -f strace ./a.out

[pid 17864] ptrace(PTRACE_TRACEME, 0, 0, 0) = -1 EPERM (Operation not permitted)
[pid 17864] write(2, "strace: test_ptrace_setoptions_f"..., 93strace:
test_ptrace_setoptions_for_all: PTRACE_TRACEME doesn't work: Operation
not permitted
) = 93
[pid 17864] exit_group(1)               = ?
[pid 17864] +++ exited with 1 +++

> Manual invocation of this command tells us the reason. On alpha, it says:
>
> $ strace -f -e trace=sendfile64 ./a.out
> strace: invalid system call 'sendfile64'
>
>> The Alpha stack trace you send also indicates a failure in this test.
>> It could be for the same reason; hard to say.  The Alpha strace output
>> you send doesn't tell me much, since it wasn't done with -f.
>
> I have resent you the strace. The important part is:
>
> 7407  write(2, "strace: invalid system call 'sen"..., 41 <unfinished ...>
> 7405  <... sigreturn resumed> )         = -1
> 7407  <... write resumed> )             = 41
> 7405  osf_sigprocmask(SIG_BLOCK, [] <unfinished ...>
> 7407  exit_group(1)                     = ?
> 7405  <... osf_sigprocmask resumed> )   = 0 (old mask [])
> 7405  connect(7, {sa_family=AF_INET, sin_port=htons(32998),
> sin_addr=inet_addr("127.0.0.1")}, 16) = 0
> 7407  +++ exited with 1 +++
>
> The child exited with error, but this is not handled in the test, and
> the test waits for dead process indefinitely.
>
> I think that the test should detect, if test system supports
> sendfile64 and perhaps also handle invocation failure from the child
> process.

Attached patch fixes failures on alpha. However, the patch doesn't
detect the failure from strace invocation, so the testcase could still
wait for the dead child process.

The patch was tested on x86_64-linux-gnu and alpha-linux-gnu.

Uros.
Ian Taylor - July 24, 2013, 1:11 p.m.
On Wed, Jul 24, 2013 at 2:24 AM, Uros Bizjak <ubizjak@gmail.com> wrote:
> On Wed, Jul 24, 2013 at 9:09 AM, Uros Bizjak <ubizjak@gmail.com> wrote:
>
>>>> The test was re-run with GOTESTFLAGS=--keep. When running the
>>>> resulting a.out with "strace -f -o strace-x86_64 ./a.out" from the
>>>> saved test directory, the test behaved in the same way as on alpha -
>>>> it hever finished. I have attached the resulting trace (the test was
>>>> killed with ctrl-c after some time).
>>>
>>> Thanks.  The problematic test is TestLinuxSendfile in
>>> libgo/net/http/fs_test.go.  That test binary invokes itself using
>>> strace.  In the trace here, that strace fails:
>>>
>>> 8511  ptrace(PTRACE_TRACEME, 0, 0, 0)   = -1 EPERM (Operation not permitted)
>>> 8511  write(2, "strace: test_ptrace_setoptions_f"..., 96) = 96
>>>
>>> The strace is supposed to start up a little server, and the test
>>> binary tries to connect to that server.  Since the server hasn't
>>> started, the test times out.
>>>
>>> The strace invocation is
>>>
>>> strace -f -q -e trace=sendfile,sendfile64 ./a.out
>>> -test.run=TestLinuxSendfileChild
>>>
>>> Any idea why that would fail?
>
> It looks you can't trace a traced process:
>
> $ strace -f strace ./a.out
>
> [pid 17864] ptrace(PTRACE_TRACEME, 0, 0, 0) = -1 EPERM (Operation not permitted)
> [pid 17864] write(2, "strace: test_ptrace_setoptions_f"..., 93strace:
> test_ptrace_setoptions_for_all: PTRACE_TRACEME doesn't work: Operation
> not permitted
> ) = 93
> [pid 17864] exit_group(1)               = ?
> [pid 17864] +++ exited with 1 +++
>
>> Manual invocation of this command tells us the reason. On alpha, it says:
>>
>> $ strace -f -e trace=sendfile64 ./a.out
>> strace: invalid system call 'sendfile64'
>>
>>> The Alpha stack trace you send also indicates a failure in this test.
>>> It could be for the same reason; hard to say.  The Alpha strace output
>>> you send doesn't tell me much, since it wasn't done with -f.
>>
>> I have resent you the strace. The important part is:
>>
>> 7407  write(2, "strace: invalid system call 'sen"..., 41 <unfinished ...>
>> 7405  <... sigreturn resumed> )         = -1
>> 7407  <... write resumed> )             = 41
>> 7405  osf_sigprocmask(SIG_BLOCK, [] <unfinished ...>
>> 7407  exit_group(1)                     = ?
>> 7405  <... osf_sigprocmask resumed> )   = 0 (old mask [])
>> 7405  connect(7, {sa_family=AF_INET, sin_port=htons(32998),
>> sin_addr=inet_addr("127.0.0.1")}, 16) = 0
>> 7407  +++ exited with 1 +++
>>
>> The child exited with error, but this is not handled in the test, and
>> the test waits for dead process indefinitely.
>>
>> I think that the test should detect, if test system supports
>> sendfile64 and perhaps also handle invocation failure from the child
>> process.
>
> Attached patch fixes failures on alpha. However, the patch doesn't
> detect the failure from strace invocation, so the testcase could still
> wait for the dead child process.
>
> The patch was tested on x86_64-linux-gnu and alpha-linux-gnu.

Thanks a lot.  Committed to mainline and 4.8 branch.

I looked at the kernel sources, and there does seem to be a sendfile64
system call on alpha (system call 239).  I wonder how strace decides
which system calls are supported.

Ian

Patch

Index: go/net/http/fs_test.go
===================================================================
--- go/net/http/fs_test.go	(revision 201182)
+++ go/net/http/fs_test.go	(working copy)
@@ -696,8 +696,13 @@ 
 	}
 	defer ln.Close()
 
+	trace := "trace=sendfile"
+	if runtime.GOARCH != "alpha" {
+		trace = trace + ",sendfile64"
+	}
+
 	var buf bytes.Buffer
-	child := exec.Command("strace", "-f", "-q", "-e", "trace=sendfile,sendfile64", os.Args[0], "-test.run=TestLinuxSendfileChild")
+	child := exec.Command("strace", "-f", "-q", "-e", trace, os.Args[0], "-test.run=TestLinuxSendfileChild")
 	child.ExtraFiles = append(child.ExtraFiles, lnf)
 	child.Env = append([]string{"GO_WANT_HELPER_PROCESS=1"}, os.Environ()...)
 	child.Stdout = &buf