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[Bug tapsets/16541] New: nfsd tapset has errors
- From: "dsmith at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sourceware dot org
- Date: Fri, 07 Feb 2014 19:28:49 +0000
- Subject: [Bug tapsets/16541] New: nfsd tapset has errors
- Auto-submitted: auto-generated
https://sourceware.org/bugzilla/show_bug.cgi?id=16541
Bug ID: 16541
Summary: nfsd tapset has errors
Product: systemtap
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: tapsets
Assignee: systemtap at sourceware dot org
Reporter: dsmith at redhat dot com
On newer kernels, the nfsd tapset has errors. This tapset gets tested by the
buildok.exp testcase, but since the test gets kfail'ed, these errors have gone
unnoticed.
Looking at the output of the following command, there are 2 classes of errors:
# stap -v -p4 src/testsuite/buildok/nfsd-detailed.stp
1) nfsd.close error accessing $filp.
====
semantic error: not accessible at this address [man error::dwarf] (0x18707,
dieoffset: 0x5a932): identifier '$filp' at :1100:29
source: filename = __file_filename($filp)
====
The first thing to do is see what parameters (if any) stap can see for that
function:
# stap -L 'module("nfsd").function("nfsd_close").*'
module("nfsd").function("nfsd_close@fs/nfsd/vfs.c:856").call $filp:struct file*
module("nfsd").function("nfsd_close@fs/nfsd/vfs.c:856").exported $filp:struct
file*
module("nfsd").function("nfsd_close@fs/nfsd/vfs.c:856").inline
module("nfsd").function("nfsd_close@fs/nfsd/vfs.c:856").return $filp:struct
file*
So, stap can see $filp except for the inlined version, which isn't too
surprising since gcc typically generates poor debuginfo for inlined functions.
The solution here is to use the '.call' version on the probe points. This will
ensure that stap can find $filp and 'nfsd.close' probe hits will match more
closely with 'nfsd.close.return' probe hits.
2) Problems accessing cr_uid/cr_gid
====
semantic error: 'struct {...}' is being accessed instead of a member:
identifier '$rqstp' at /usr/local/share/systemtap/tapset/linux/nfsd.stp:233:8
source: uid = $rqstp->rq_cred->cr_uid
====
This is happening because this kernel has CONFIG_UIDGID_STRICT_TYPE_CHECKS on,
and uid/gid fields are simple integers anymore, but structures.
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