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[SCM] systemtap: system-wide probe/trace tool branch, master, updated. release-1.0-114-g720bbfc
- From: srikar at sourceware dot org
- To: systemtap-cvs at sourceware dot org
- Date: 19 Oct 2009 08:17:34 -0000
- Subject: [SCM] systemtap: system-wide probe/trace tool branch, master, updated. release-1.0-114-g720bbfc
- Reply-to: systemtap at sourceware dot org
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- Log -----------------------------------------------------------------
commit 720bbfc68d9e7dfd8c37587c6a61da75d6aab4fa
Author: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Date: Mon Oct 19 13:44:21 2009 +0530
Avoid lockdep warnings.
uprobe_fork_uproc() runs with parent_uproc->rwsem locked.
However uprobe_mk_process() that gets called within uprobe_fork_uproc()
also locks child_uproc->rwsem after initializing it.
Lockdep report confuses this to acquiring a lock that already has been
acquired and suggests using sub-classes.
The alternatives we have are:
1. use classes level to distinguish different uproc structures.
2. unlock parent_uproc->rwsem before we call uprobe_fork_uproc().
3. dont try locking child_uproc->rwsem; since we are protected by
uproc_mutex as well as parent_uproc->rwsem;
We use the last approach.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---
-----------------------------------------------------------------------
Summary of changes:
runtime/uprobes/uprobes.c | 24 +++++++++++++++++-------
runtime/uprobes2/uprobes.c | 24 +++++++++++++++++-------
2 files changed, 34 insertions(+), 14 deletions(-)
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systemtap: system-wide probe/trace tool