[Bug tapsets/6762] New: Some syscalls functions just wrappers for other syscalls

[Bug tapsets/6762] New: Some syscalls functions just wrappers for other syscalls

[wcohen at redhat dot com]

When looking through the results of the nightly tests on Red Hat Enterprise
Linux 5 (2.6.18-92.1.6.el5 kernel) a number of the syscall.stp test failed:

FAIL: 64-bit access
FAIL: 64-bit chmod
FAIL: 64-bit forkwait
FAIL: 64-bit link
FAIL: 32-bit access
FAIL: 32-bit chmod
FAIL: 32-bit forkwait
FAIL: 32-bit link

Looking through the output found output like the following for the access test:

access: access ("foobar1", F_OK) = 
  access: faccessat (AT_FDCWD, "foobar1", F_OK) = 0
0

The sys_access function is just a wrapper for the sys_faccessat function. Thus,
the faccessat output occurs in the middle. This is not what users are expecting.

Look at 2.6.26 kernel also saw similar problems with sys_chmod and sys_creat.

-- 
           Summary: Some syscalls functions just wrappers for other syscalls
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: tapsets
        AssignedTo: systemtap at sources dot redhat dot com
        ReportedBy: wcohen at redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=6762

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[Bug tapsets/6762] Some syscalls functions just wrappers for other syscalls

[fche at redhat dot com]

------- Additional Comments From fche at redhat dot com  2008-10-20 16:50 -------
One possible fix is to extend the syscalls tapset thusly:

# add someplace
global syscall_inplay
probe process.syscall { syscall_inplay[tid()] = $syscall }
probe process.syscall.return { delete syscall_inplay[tid()] }
probe process.thread.end { delete syscall_inplay[tid()] }

# then for each "nestable" system call handler
probe syscall.faccessat = kernel.function(" ...") {
   if (syscall_inplay[tid()]) next;
}


Alternately, one can instrument just the "nester" and "nestee" probe
pairs with similar logic, without general system-wide utrace syscall
probes.


Alternately, one can kludge the test case to accept and ignore such
nesting.  :-(


-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6762

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[Bug tapsets/6762] Some syscalls functions just wrappers for other syscalls

[mjw at redhat dot com]

------- Additional Comments From mjw at redhat dot com  2008-10-20 18:53 -------
(In reply to comment #1)
> Alternately, one can kludge the test case to accept and ignore such
> nesting.  :-(

I actually did this a while ago:

commit 5311c037f83f66967f9de4cc66815f93940bb005
Author: Mark Wielaard <mjw@redhat.com>
Date:   Sun Oct 5 00:29:49 2008 +0200

    Expect syscall faccessat, fchmodat, linkat, symlinkat, readlinkat chain-call

diff --git a/testsuite/systemtap.syscall/ChangeLog b/testsuite/systemtap.syscall
index 772f980..7cb97df 100644
--- a/testsuite/systemtap.syscall/ChangeLog
+++ b/testsuite/systemtap.syscall/ChangeLog
@@ -1,3 +1,11 @@
+2008-10-04  Mark Wielaard  <mjw@redhat.com>
+
+       * access.c: sys_access() calls through to sys_faccessat().
+       * chmod.c: sys_chmod() calls through to sys_fchmodat().
+       * link.c: sys_link() calls through to sys_linkat(),
+       sys_symlink() calls through to sys_symlinkat(),
+       sys_readlink() calls through to sys_readlinkat().


-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6762

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[Bug tapsets/6762] Some syscalls functions just wrappers for other syscalls

[dsmith at redhat dot com]

------- Additional Comments From dsmith at redhat dot com  2010-01-13 21:02 -------
Since these failures no longer occur on current Red Hat Enterprise
Linux 5 (2.6.18-164.el5), I'm closing this one.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dsmith at redhat dot com
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://sourceware.org/bugzilla/show_bug.cgi?id=6762

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[Bug tapsets/6762] Some syscalls functions just wrappers for other syscalls

[fche at redhat dot com]

------- Additional Comments From fche at redhat dot com  2010-02-16 20:04 -------
This problem periodically reoccurs; we will have to deal with it
properly.  See bug #11263.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |


http://sourceware.org/bugzilla/show_bug.cgi?id=6762

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