[Bug translator/3016] New: error accessing anonymous struct/union memeber

[Bug translator/3016] New: error accessing anonymous struct/union memeber

[guanglei at cn dot ibm dot com]

stap works fine with this script:

probe kernel.function("do_mpage_readpage")
{
  printf("%p", $page)
}

But it will generate an error with this script:

probe kernel.function("do_mpage_readpage")
{
        printf("%p", $page->mapping) 
}

stap -vv says:
...
Pass 1: parsed user script and 40 library script(s) in 310usr/0sys/372real ms.
probe do_mpage_readpage@fs/mpage.c:179 pc=0xc0000000000e716c
semantic error: unresolved target-symbol expression: identifier '$page' at
b.stp:3:15
...

The struct page is defined in "include/linux/mm.h" and mapping is an anonymous
struct member of struct page:

struct page {
      unsigned long flags;
      atomic_t _count; 
      atomic_t _mapcount; 
      union {
          struct {
              unsigned long private;
              struct address_space *mapping;
          };
      ...
}

-- 
           Summary: error accessing anonymous struct/union memeber
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: translator
        AssignedTo: systemtap at sources dot redhat dot com
        ReportedBy: guanglei at cn dot ibm dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=3016

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[Bug translator/3016] error accessing anonymous struct/union memeber

[dsmith at redhat dot com]

------- Additional Comments From dsmith at redhat dot com  2006-08-09 20:00 -------
I've duplicated this problem, and it only occurs with the anonymous struct. 
Accessing other 'struct page' members works correctly, i.e.:

probe kernel.function("do_mpage_readpage")
{
	printf("%p", $page->flags) 
}




-- 


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[Bug translator/3016] error accessing anonymous struct/union memeber

[roland at gnu dot org]

------- Additional Comments From roland at gnu dot org  2006-08-09 20:54 -------
Yes, looking for anonymous structs/unions is just not handled.
I can whip up loc2c-test changes to support it, to give a model for what the
translator needs to do.  It's straightforward.

-- 


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[Bug translator/3016] error accessing anonymous struct/union memeber

[mhiramat at redhat dot com]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mhiramat at redhat dot com


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[Bug translator/3016] error accessing anonymous struct/union memeber

[mark at klomp dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mwielaard at redhat dot com


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[Bug translator/3016] error accessing anonymous struct/union memeber

[prerna at linux dot vnet dot ibm dot com]

------- Additional Comments From prerna at linux dot vnet dot ibm dot com  2008-09-19 06:55 -------
*** Bug 4519 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |wcohen at redhat dot com


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[Bug translator/3016] error accessing anonymous struct/union memeber

[prerna at linux dot vnet dot ibm dot com]

------- Additional Comments From prerna at linux dot vnet dot ibm dot com  2008-09-26 06:24 -------
Changed the translate_components() function of tapsets.cxx to call itself
recursively for every instance of anonymous struct / union present as a member
in a given struct/ union.

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


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[Bug translator/3016] error accessing anonymous struct/union memeber

[mjw at redhat dot com]

------- Additional Comments From mjw at redhat dot com  2008-10-01 11:39 -------
I adjusted the test case a little so that it works on both older and newer
kernels by using the mapping field as in the first comment.

commit dd4918442a55569175bda0575f746e84c99cee58
Author: Mark Wielaard <mjw@redhat.com>
Date:   Wed Oct 1 13:38:16 2008 +0200

    Adjust semok/thirtythree.stp test to pass on older kernels.

diff --git a/testsuite/ChangeLog b/testsuite/ChangeLog
index f3fad07..4825cd2 100644
--- a/testsuite/ChangeLog
+++ b/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2008-10-01  Mark Wielaard  <mjw@redhat.com>
+
+       * semok/thirtythree.stp: Use page->mapping instead of page->inuse
+       as annonymous struct value (also available in older kernels).
+
 2008-09-26  Frank Ch. Eigler  <fche@elastic.org>
 
        PR 6916.
diff --git a/testsuite/semok/thirtythree.stp b/testsuite/semok/thirtythree.stp
index d5171f6..9007037 100755
--- a/testsuite/semok/thirtythree.stp
+++ b/testsuite/semok/thirtythree.stp
@@ -1,5 +1,5 @@
 #! stap -p2
 # Per bz3016, this should get through the semantic pass without warnings.
 probe kernel.function("do_mpage_readpage") {
-       printf("\n page ->inuse %u",$page->inuse)
+       printf("\n page->mapping %p",$page->mapping)
 }


-- 


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