From: Giovanni Gherdovich <ggherdovich@suse.cz>
To: systemtap@sourceware.org
Subject: Error when using @container_of
Date: Mon, 22 Apr 2019 10:01:00 -0000 [thread overview]
Message-ID: <1555927560.2268.2.camel@suse.cz> (raw)
Hello,
when I use the macro @container_of in systemtap I'm getting an error I don't
understand.
This is my tapset:
#!/root/systemtap-latest/bin/stap
probe kernel.function("__update_load_avg_se") {
printf("%x\n", @container_of($se, "struct task_struct", se));
exit();
}
and this is the error:
# ./repro.stp
semantic error: 'struct task_struct' (./include/linux/sched.h:602) is being
accessed instead of a member such as '->acct_rss_mem1': operator '@cast' at
/root/systemtap-latest/share/systemtap/tapset/container_of.stpm:2:5
source: @cast(@ptr - @offsetof(@type, @member), @type)
^
in expansion of macro: operator '@container_of' at ./repro.stp:4:17
source: printf("%x\n", @container_of($se, "struct task_struct", se));
^
Pass 2: analysis failed. [man error::pass2]
What I'm trying to do here is to get an object of type sched_entity (the
target variable $se which is a parameter of the function
__update_load_avg_se()) and from there grab the task_struct that contains said
sched_entity. If the sched_entity in question is actually a task (and not a
group), this operation should make sense; for example the inlined function
task_of() from kernel/sched/fair.c does exactly that.
I'm using a v5.0 kernel and the latest systemtap from the git repo:
# /root/systemtap-latest/bin/stap --version
Systemtap translator/driver (version 4.1/0.168, commit release-4.0-187-g288c53892665 + changes)
Copyright (C) 2005-2019 Red Hat, Inc. and others
This is free software; see the source for copying conditions.
tested kernel versions: 2.6.18 ... 5.1-rc2
enabled features: BPF PYTHON2 LIBXML2 NLS READLINE
Regards,
Giovanni Gherdovich
next reply other threads:[~2019-04-22 10:01 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-22 10:01 Giovanni Gherdovich [this message]
2019-04-25 8:13 ` Giovanni Gherdovich
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